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  <front>
    <journal-meta>
      <journal-id journal-id-type="publisher-id">JMIR</journal-id>
      <journal-id journal-id-type="nlm-ta">J Med Internet Res</journal-id>
      <journal-title>Journal of Medical Internet Research</journal-title>
      <issn pub-type="epub">1438-8871</issn>
      <publisher>
        <publisher-name>JMIR Publications</publisher-name>
        <publisher-loc>Toronto, Canada</publisher-loc>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="publisher-id">v24i11e40160</article-id>
      <article-id pub-id-type="pmid">36343184</article-id>
      <article-id pub-id-type="doi">10.2196/40160</article-id>
      <article-categories>
        <subj-group subj-group-type="heading">
          <subject>Original Paper</subject>
        </subj-group>
        <subj-group subj-group-type="article-type">
          <subject>Original Paper</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>Using Natural Language Processing to Explore “Dry January” Posts on Twitter: Longitudinal Infodemiology Study</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="editor">
          <name>
            <surname>Basch</surname>
            <given-names>Corey</given-names>
          </name>
        </contrib>
      </contrib-group>
      <contrib-group>
        <contrib contrib-type="reviewer">
          <name>
            <surname>Allem</surname>
            <given-names>Jon-Patrick</given-names>
          </name>
        </contrib>
        <contrib contrib-type="reviewer">
          <name>
            <surname>Field</surname>
            <given-names>Matt</given-names>
          </name>
        </contrib>
      </contrib-group>
      <contrib-group>
        <contrib id="contrib1" contrib-type="author" corresp="yes">
          <name name-style="western">
            <surname>Russell</surname>
            <given-names>Alex M</given-names>
          </name>
          <degrees>PhD</degrees>
          <xref rid="aff1" ref-type="aff">1</xref>
          <address>
            <institution>Center for Public Health and Technology</institution>
            <institution>Department of Health, Human Performance, and Recreation</institution>
            <institution>University of Arkansas</institution>
            <addr-line>HPER Building, 308-V</addr-line>
            <addr-line>Fayetteville, AR, 72701</addr-line>
            <country>United States</country>
            <phone>1 479 575 8672</phone>
            <email>ar117@uark.edu</email>
          </address>
          <ext-link ext-link-type="orcid">https://orcid.org/0000-0002-8182-4057</ext-link>
        </contrib>
        <contrib id="contrib2" contrib-type="author">
          <name name-style="western">
            <surname>Valdez</surname>
            <given-names>Danny</given-names>
          </name>
          <degrees>PhD</degrees>
          <xref rid="aff2" ref-type="aff">2</xref>
          <ext-link ext-link-type="orcid">https://orcid.org/0000-0002-2355-9881</ext-link>
        </contrib>
        <contrib id="contrib3" contrib-type="author">
          <name name-style="western">
            <surname>Chiang</surname>
            <given-names>Shawn C</given-names>
          </name>
          <degrees>MPH</degrees>
          <xref rid="aff1" ref-type="aff">1</xref>
          <ext-link ext-link-type="orcid">https://orcid.org/0000-0002-2182-9454</ext-link>
        </contrib>
        <contrib id="contrib4" contrib-type="author">
          <name name-style="western">
            <surname>Montemayor</surname>
            <given-names>Ben N</given-names>
          </name>
          <degrees>PhD</degrees>
          <xref rid="aff3" ref-type="aff">3</xref>
          <ext-link ext-link-type="orcid">https://orcid.org/0000-0002-3330-1323</ext-link>
        </contrib>
        <contrib id="contrib5" contrib-type="author">
          <name name-style="western">
            <surname>Barry</surname>
            <given-names>Adam E</given-names>
          </name>
          <degrees>PhD</degrees>
          <xref rid="aff3" ref-type="aff">3</xref>
          <ext-link ext-link-type="orcid">https://orcid.org/0000-0001-6527-6866</ext-link>
        </contrib>
        <contrib id="contrib6" contrib-type="author">
          <name name-style="western">
            <surname>Lin</surname>
            <given-names>Hsien-Chang</given-names>
          </name>
          <degrees>PhD</degrees>
          <xref rid="aff2" ref-type="aff">2</xref>
          <ext-link ext-link-type="orcid">https://orcid.org/0000-0001-9151-2172</ext-link>
        </contrib>
        <contrib id="contrib7" contrib-type="author">
          <name name-style="western">
            <surname>Massey</surname>
            <given-names>Philip M</given-names>
          </name>
          <degrees>PhD</degrees>
          <xref rid="aff1" ref-type="aff">1</xref>
          <ext-link ext-link-type="orcid">https://orcid.org/0000-0002-0577-8618</ext-link>
        </contrib>
      </contrib-group>
      <aff id="aff1">
        <label>1</label>
        <institution>Center for Public Health and Technology</institution>
        <institution>Department of Health, Human Performance, and Recreation</institution>
        <institution>University of Arkansas</institution>
        <addr-line>Fayetteville, AR</addr-line>
        <country>United States</country>
      </aff>
      <aff id="aff2">
        <label>2</label>
        <institution>Department of Applied Health Science</institution>
        <institution>School of Public Health</institution>
        <institution>Indiana University</institution>
        <addr-line>Bloomington, IN</addr-line>
        <country>United States</country>
      </aff>
      <aff id="aff3">
        <label>3</label>
        <institution>Department of Health and Kinesiology</institution>
        <institution>Texas A&#38;M University</institution>
        <addr-line>College Station, TX</addr-line>
        <country>United States</country>
      </aff>
      <author-notes>
        <corresp>Corresponding Author: Alex M Russell <email>ar117@uark.edu</email></corresp>
      </author-notes>
      <pub-date pub-type="collection">
        <month>11</month>
        <year>2022</year>
      </pub-date>
      <pub-date pub-type="epub">
        <day>18</day>
        <month>11</month>
        <year>2022</year>
      </pub-date>
      <volume>24</volume>
      <issue>11</issue>
      <elocation-id>e40160</elocation-id>
      <history>
        <date date-type="received">
          <day>8</day>
          <month>6</month>
          <year>2022</year>
        </date>
        <date date-type="rev-request">
          <day>7</day>
          <month>10</month>
          <year>2022</year>
        </date>
        <date date-type="rev-recd">
          <day>13</day>
          <month>10</month>
          <year>2022</year>
        </date>
        <date date-type="accepted">
          <day>25</day>
          <month>10</month>
          <year>2022</year>
        </date>
      </history>
      <copyright-statement>©Alex M Russell, Danny Valdez, Shawn C Chiang, Ben N Montemayor, Adam E Barry, Hsien-Chang Lin, Philip M Massey. Originally published in the Journal of Medical Internet Research (https://www.jmir.org), 18.11.2022.</copyright-statement>
      <copyright-year>2022</copyright-year>
      <license license-type="open-access" xlink:href="https://creativecommons.org/licenses/by/4.0/">
        <p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in the Journal of Medical Internet Research, is properly cited. The complete bibliographic information, a link to the original publication on https://www.jmir.org/, as well as this copyright and license information must be included.</p>
      </license>
      <self-uri xlink:href="https://www.jmir.org/2022/11/e40160" xlink:type="simple"/>
      <abstract>
        <sec sec-type="background">
          <title>Background</title>
          <p>Dry January, a temporary alcohol abstinence campaign, encourages individuals to reflect on their relationship with alcohol by temporarily abstaining from consumption during the month of January. Though Dry January has become a global phenomenon, there has been limited investigation into Dry January participants’ experiences. One means through which to gain insights into individuals’ Dry January-related experiences is by leveraging large-scale social media data (eg, Twitter chatter) to explore and characterize public discourse concerning Dry January.</p>
        </sec>
        <sec sec-type="objective">
          <title>Objective</title>
          <p>We sought to answer the following questions: (1) What themes are present within a corpus of tweets about Dry January, and is there consistency in the language used to discuss Dry January across multiple years of tweets (2020-2022)? (2) Do unique themes or patterns emerge in Dry January 2021 tweets after the onset of the COVID-19 pandemic? and (3) What is the association with tweet composition (ie, sentiment and human-authored vs bot-authored) and engagement with Dry January tweets?</p>
        </sec>
        <sec sec-type="methods">
          <title>Methods</title>
          <p>We applied natural language processing techniques to a large sample of tweets (n=222,917) containing the term “dry january” or “dryjanuary” posted from December 15 to February 15 across three separate years of participation (2020-2022). Term frequency inverse document frequency, k-means clustering, and principal component analysis were used for data visualization to identify the optimal number of clusters per year. Once data were visualized, we ran interpretation models to afford within-year (or within-cluster) comparisons. Latent Dirichlet allocation topic modeling was used to examine content within each cluster per given year. Valence Aware Dictionary and Sentiment Reasoner sentiment analysis was used to examine affect per cluster per year. The Botometer automated account check was used to determine average bot score per cluster per year. Last, to assess user engagement with Dry January content, we took the average number of likes and retweets per cluster and ran correlations with other outcome variables of interest.</p>
        </sec>
        <sec sec-type="results">
          <title>Results</title>
          <p>We observed several similar topics per year (eg, Dry January resources, Dry January health benefits, updates related to Dry January progress), suggesting relative consistency in Dry January content over time. Although there was overlap in themes across multiple years of tweets, unique themes related to individuals’ experiences with alcohol during the midst of the COVID-19 global pandemic were detected in the corpus of tweets from 2021. Also, tweet composition was associated with engagement, including number of likes, retweets, and quote-tweets per post. Bot-dominant clusters had fewer likes, retweets, or quote tweets compared with human-authored clusters.</p>
        </sec>
        <sec sec-type="conclusions">
          <title>Conclusions</title>
          <p>The findings underscore the utility for using large-scale social media, such as discussions on Twitter, to study drinking reduction attempts and to monitor the ongoing dynamic needs of persons contemplating, preparing for, or actively pursuing attempts to quit or cut down on their drinking.</p>
        </sec>
      </abstract>
      <kwd-group>
        <kwd>alcohol</kwd>
        <kwd>drinking</kwd>
        <kwd>social media</kwd>
        <kwd>Twitter</kwd>
        <kwd>Dry January</kwd>
        <kwd>infodemiology</kwd>
        <kwd>infoveillance</kwd>
        <kwd>natural language processing</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec sec-type="introduction">
      <title>Introduction</title>
      <sec>
        <title>Background</title>
        <p>“Dry January”—a public health campaign aimed at encouraging individuals to reflect on their relationship with alcohol by temporarily abstaining from consumption during the month of January—originated in the United Kingdom in 2013 [<xref ref-type="bibr" rid="ref1">1</xref>,<xref ref-type="bibr" rid="ref2">2</xref>]. Those who register to participate in the month-long challenge via the Alcohol Change UK website are provided added accountability and support through access to interactive online resources (eg, TryDry mobile application) and health communication messaging highlighting the benefits of temporary alcohol abstinence (eg, emails and social media messaging about financial health, physical health, and mental health benefits) [<xref ref-type="bibr" rid="ref3">3</xref>]. Dry January is theorized to confer benefits to participants via social contagion, which suggests widespread changes in health beliefs and behaviors are more likely to occur when a supportive community or subgroup of people endorse similar motivations and goals [<xref ref-type="bibr" rid="ref4">4</xref>-<xref ref-type="bibr" rid="ref6">6</xref>].</p>
        <p>Prior research evaluating the characteristics of Dry January participants and the efficacy for the campaign in terms of reducing alcohol consumption and enhancing quality of life indicators has primarily focused on official Dry January registrants (ie, those who reside in the United Kingdom and officially registered for the challenge on the Alcohol Change UK website) [<xref ref-type="bibr" rid="ref7">7</xref>-<xref ref-type="bibr" rid="ref9">9</xref>]. Most of these studies have demonstrated that official participation in the temporary abstinence initiative is associated with numerous short- and long-term benefits, including reductions in alcohol consumption, increases in alcohol-refusal skills, saving money, improved sleep, increased energy, weight loss, and enhanced psychological well-being [<xref ref-type="bibr" rid="ref5">5</xref>,<xref ref-type="bibr" rid="ref7">7</xref>-<xref ref-type="bibr" rid="ref9">9</xref>]. However, Case et al [<xref ref-type="bibr" rid="ref10">10</xref>] found that increased participation in Dry January in England between 2015 and 2018 was not associated with population-level reductions in alcohol consumption over the 4-year period.</p>
        <p>One potential explanation for these mixed findings could be that, although the number of officially registered Dry January participants in the United Kingdom has risen from 4000 in 2013 to 130,000 in 2021 [<xref ref-type="bibr" rid="ref1">1</xref>], this represents only a small minority of the public who are informally participating in the temporary alcohol abstinence initiative (an estimated 6.5 million Britons reported planning to give up alcohol during the month of January in 2021) [<xref ref-type="bibr" rid="ref11">11</xref>]. Additionally, the reach of the Dry January campaign has extended beyond the United Kingdom and has become a global cultural phenomenon with millions of informal participants worldwide [<xref ref-type="bibr" rid="ref12">12</xref>]. For example, an estimated 15% to 19% of American adults reported going alcohol-free during January 2022 [<xref ref-type="bibr" rid="ref13">13</xref>,<xref ref-type="bibr" rid="ref14">14</xref>]. This has coincided with increasing news media attention [<xref ref-type="bibr" rid="ref15">15</xref>,<xref ref-type="bibr" rid="ref16">16</xref>], social media engagement, and Dry January–related alcohol industry promotional efforts (eg, marketing of nonalcoholic alternatives) [<xref ref-type="bibr" rid="ref17">17</xref>]. For the millions of individuals who <italic>unofficially</italic> participate in alcohol abstinence during the month of January, there remains a paucity of investigations and a need to better understand their experiences in attempting to abstain from alcohol during the month of January. One such means through which to gain insights into individuals’ Dry January-related experiences is by leveraging large-scale social media data (eg, Twitter chatter) to explore and characterize public discourse concerning Dry January. </p>
      </sec>
      <sec>
        <title>Infodemiology</title>
        <p>Infodemiology (the epidemiology of online information, such as using search result data or social media posts to inform public health and policy) and infoveillance (longitudinal tracking of online information for surveillance purposes) are emerging fields [<xref ref-type="bibr" rid="ref18">18</xref>-<xref ref-type="bibr" rid="ref21">21</xref>]. The last decade has witnessed a proliferation in Twitter and other social media platform usage, and many individuals rely on these platforms for health information [<xref ref-type="bibr" rid="ref22">22</xref>-<xref ref-type="bibr" rid="ref24">24</xref>]. Along these lines, infodemiology methods have been used to systematically monitor public sentiment and characterize communication concerning various health topics using publicly available social media data, such as Twitter posts [<xref ref-type="bibr" rid="ref21">21</xref>]. Though not intended to replace, but rather complement, more traditional methods, infodemiology offers several advantages, including the ease and rapidity with which data can be collected, allowing for the ability to detect changes in public attention and attitudes in real time [<xref ref-type="bibr" rid="ref18">18</xref>-<xref ref-type="bibr" rid="ref20">20</xref>]. Previous studies leveraging Twitter as a data source have provided insights into a variety of health topics, including alcohol-related behaviors [<xref ref-type="bibr" rid="ref25">25</xref>-<xref ref-type="bibr" rid="ref28">28</xref>], tobacco use and cessation [<xref ref-type="bibr" rid="ref29">29</xref>-<xref ref-type="bibr" rid="ref32">32</xref>], drug use [<xref ref-type="bibr" rid="ref33">33</xref>,<xref ref-type="bibr" rid="ref34">34</xref>], mental health [<xref ref-type="bibr" rid="ref35">35</xref>,<xref ref-type="bibr" rid="ref36">36</xref>], vaccination [<xref ref-type="bibr" rid="ref37">37</xref>,<xref ref-type="bibr" rid="ref38">38</xref>], and the spread of health-related misinformation [<xref ref-type="bibr" rid="ref39">39</xref>]. Moreover, Twitter has been used as a real-time surveillance tool to monitor reactions to public health prevention campaigns [<xref ref-type="bibr" rid="ref40">40</xref>] and public policy changes [<xref ref-type="bibr" rid="ref41">41</xref>,<xref ref-type="bibr" rid="ref42">42</xref>], providing timely information to public health researchers, practitioners, and policy makers.</p>
      </sec>
      <sec>
        <title>Alcohol Use Infodemiology on Twitter</title>
        <p>A growing number of studies have explored alcohol-related, user-generated content posted on Twitter [<xref ref-type="bibr" rid="ref25">25</xref>-<xref ref-type="bibr" rid="ref28">28</xref>]. For instance, Cavazos-Rehg et al [<xref ref-type="bibr" rid="ref25">25</xref>] was among the first to characterize a large sample of alcohol-related tweets, finding that the vast majority of such tweets expressed positive sentiment toward alcohol and frequently glamorized heavy drinking, while rarely portraying any alcohol-related negative consequences. Other studies have examined tweets concerning alcohol-related blackouts [<xref ref-type="bibr" rid="ref26">26</xref>,<xref ref-type="bibr" rid="ref28">28</xref>,<xref ref-type="bibr" rid="ref43">43</xref>]; increases in alcohol-related blackout tweets in early 2020 were in line with population-level increases in alcohol consumption observed during the COVID-19 pandemic [<xref ref-type="bibr" rid="ref28">28</xref>]. Weitzman et al [<xref ref-type="bibr" rid="ref44">44</xref>] compared state-level alcohol use–related Twitter posts and Google Trends search data with 3 years of national epidemiological survey data, providing support for using search activity and social media data to complement epidemiological approaches to monitor alcohol use and inform prevention efforts. However, there has been a dearth of infodemiology studies focused on efforts to quit or cut down on drinking, such as drinking reduction attempts associated with the Dry January temporary alcohol abstinence campaign [<xref ref-type="bibr" rid="ref8">8</xref>,<xref ref-type="bibr" rid="ref9">9</xref>].</p>
      </sec>
      <sec>
        <title>This Study</title>
        <p>The purpose of this study was to identify and describe a corpus of Dry January–related tweets authored by the public and social bots across 3 years of participation (2020-2022) and to evaluate whether there were changes in themes and sentiment from year to year in response to the COVID-19 pandemic. We sought to compare conversational themes over time to demonstrate the potential use for social media platforms—such as Twitter—to be used to study drinking reduction attempts and to monitor the ongoing dynamic needs of persons actively involved in or thinking about attempts to quit or cut down on drinking. To achieve this objective, we applied natural language processing (NLP) techniques to a large sample of Twitter data (n=222,917), spanning 3 distinct years (2020-2022), to answer the following research questions (RQs):</p>
        <list list-type="order">
          <list-item>
            <p>(RQ1) What themes are present within a corpus of tweets about Dry January, and is there consistency in the language used to discuss Dry January across multiple years of tweets (2020-2022)?</p>
          </list-item>
          <list-item>
            <p>(RQ2) Do unique themes or patterns emerge in Dry January 2021 tweets after the onset of the COVID-19 pandemic?</p>
          </list-item>
          <list-item>
            <p>(RQ3) What is the association between tweet composition (ie, sentiment and human-authored vs bot-authored) and engagement with Dry January tweets?</p>
          </list-item>
        </list>
      </sec>
    </sec>
    <sec sec-type="methods">
      <title>Methods</title>
      <sec>
        <title>Data Collection</title>
        <p>Tweets associated with this study, including metadata (eg, number of likes, retweets, replies) were extracted using the Twitter application programming interface (API) v2 and Python 3.9. After obtaining approval for access to the Academic Research product track of Twitter’s API v2, we identified and extracted all tweets containing the term “dry january” or “dryjanuary” posted from December 15 to February 15 across 3 separate years of participation (12/15/2019 to 02/15/2020, 12/15/2020 to 02/15/2021, and 12/15/2021 to 02/15/2022). Capturing the 2 weeks prior to and after the month of January allowed us to analyze conversations related to anticipation of Dry January, as well as those reflecting on completed Dry January attempts (whether successful or unsuccessful). We excluded all retweets, defined as the same tweet appearing multiple times in the corpus, and non-English tweets, defined as any tweets not originally written in the English language. Note, eliminating duplicate tweets and non-English tweets was done to enhance the interpretability of the NLP analyses undertaken herein [<xref ref-type="bibr" rid="ref45">45</xref>]. Overall, 70,215 tweets were extracted from 12/15/2019 to 2/15/2020, 86,378 tweets from 12/15/2020 to 2/15/2021, and 66,324 tweets from 12/15/2021 to 2/15/2022, resulting in a final sample of 222,917 tweets. All tweets collected for this study, inclusive of nonpersonally identifiable metadata, were saved into a secure repository only accessible by the research team, strictly conforming to standards for ethical data use and online privacy.</p>
      </sec>
      <sec>
        <title>Ethical Considerations</title>
        <p>Research procedures were deemed exempt by the appropriate institutional review board prior to data collection from Twitter.</p>
      </sec>
      <sec>
        <title>Analyses</title>
        <p>Our research questions were exploratory in nature. As such, we strategically selected several classes of computational informatics methods designed to extract overall themes in the corpus and project relative similarity and dissimilarity across themes. These methods can be classified into those used for data visualization (term frequency inverse document frequency [TF-IDF], k-means clustering, and principal component analysis [PCA]) and for data interpretation (latent Dirichlet allocation [LDA] topic models, Valence Aware Dictionary and Sentiment Reasoner [VADER] sentiment analysis, and Botometer automated account check).</p>
        <sec>
          <title>Data Visualization (Research Questions 1 and 2)</title>
          <sec>
            <title>Term Frequency Inverse Document Frequency</title>
            <p>TF-IDF refers to an information retrieval technique used to transform text data into numeric data [<xref ref-type="bibr" rid="ref46">46</xref>,<xref ref-type="bibr" rid="ref47">47</xref>]. Specifically, the TF-IDF algorithm creates weights for each word in a corpus, such that weights implicate (1) how important a word is in a singular tweet relative to (2) the number of times the same word was used in the entirety of the corpus. Weights per term can be interpreted as greater values equating higher word importance and lower values equating lower term importance. These weights are then transposed into a sparse matrix for further analysis.</p>
          </sec>
          <sec>
            <title>K-means Clustering</title>
            <p>K-means clustering is an unsupervised machine learning tool used to group text content into themes, or clusters. This analysis relies on the sparse matrix created by the TF-IDF calculations to categorize tweets into one of the k-clusters. The optimal number of k clusters is identified by calculating the sums of squared differences for a range of possible clusters (ie, 1 cluster to 10 clusters). The sums of squared differences for a range of k clusters are plotted along an elbow scree plot, where breaks in a plotted line indicate a possible clusters solution. For more information on k-means clustering, please see Na et al [<xref ref-type="bibr" rid="ref48">48</xref>].</p>
          </sec>
          <sec>
            <title>PCA</title>
            <p>PCA, a commonly used analysis in exploratory factor analysis, is a dimensionality technique used to reduce the complexity, or components, of data while still maintaining the integrity of the data [<xref ref-type="bibr" rid="ref49">49</xref>,<xref ref-type="bibr" rid="ref50">50</xref>]. For text mining analysis, all words assigned weights by TF-IDF that have been assigned into one of the k-clusters are reduced into simple X and Y coordinates. These coordinates are transposed onto a vector map and color coded along the predetermined optimal k-clusters. For this analysis, we examined data shape, which simply refers to the way in which data are presented on a vector map.</p>
          </sec>
        </sec>
        <sec>
          <title>Data Interpretation (Research Questions 2 and 3)</title>
          <sec>
            <title>LDA Topic Models</title>
            <p>LDA refers to an unsupervised NLP method that uses probabilistic inferencing to identify latent topics within a corpus of similar content. LDA is widely acknowledged as the most effective and precise topic modeling algorithm and has been widely applied for a variety of research areas and social issues [<xref ref-type="bibr" rid="ref51">51</xref>,<xref ref-type="bibr" rid="ref52">52</xref>].</p>
          </sec>
          <sec>
            <title>VADER</title>
            <p>VADER is a rule-based sentiment analysis attuned to social media vernacular [<xref ref-type="bibr" rid="ref53">53</xref>,<xref ref-type="bibr" rid="ref54">54</xref>]. VADER specifically examines the polarity of words in each tweet by feeding text data through a lexicon that is precoded with values for all positive and negative words in the English language. VADER scores can range from –.99 to .99. High values typically denote higher affect, or greater positivity, and lower values typically denote lower affect, or greater negativity.</p>
          </sec>
          <sec>
            <title>Botometer</title>
            <p>Botometer is a proprietary algorithm developed by the Indiana University Network Science Institute [<xref ref-type="bibr" rid="ref55">55</xref>]. Botometer is widely used to determine if content in a tweet originates from an account that is principally human-authored or principally bot-authored. Users can leverage the Botometer API and search for specific user IDs or usernames and immediately receive a score from .01 to .99. Lower scores indicate that the account likely belongs to a human; higher scores, typically above .70, indicate that the account likely belongs to an automated bot. Note that, due to limitations with the Botometer API, we were only able to subsample 500 posts per cluster per year as a rough approximation of bot activity. Our decision to use a general .70 cutoff as a delineator between likely bot and likely human account is supported by Botometer validation literature and other studies leveraging Botometer for bot detection and removal [<xref ref-type="bibr" rid="ref56">56</xref>,<xref ref-type="bibr" rid="ref57">57</xref>].</p>
          </sec>
        </sec>
        <sec>
          <title>Simple Inductive Coding and Validation (Research Questions 1, 2, and 3)</title>
          <p>Although NLP methods can analyze language data en masse, a computer cannot ascribe meaning to themes derived from such analyses nor detect certain facets of human speech such as sarcasm [<xref ref-type="bibr" rid="ref51">51</xref>]. As such, we invoked a simple inductive coding procedure in which 3 authors affiliated with this study independently reviewed approximately 50 posts per cluster per year. Authors were asked to describe the cluster in 3 or 4 words, and upon completion, the authors met to discuss overlap and differences. Key questions asked of the authors were to determine the overall content of each cluster, whether clusters were serious or humorous (ie, sarcasm), and whether the cluster seemed to promote a Dry January–related product. For humorous or sarcastic posts, we specifically looked for indicators, such as the presence of emojis, references to jokes, or exaggerated claims styled for likes. In circumstances in which unanimous consensus could not be reached, we repeated this process with 50 more randomly selected tweets until agreement was met. This process is generally deemed sufficient when dealing with mixed methods topic models on large-scale documents [<xref ref-type="bibr" rid="ref58">58</xref>], though more research on uniform mixed methods topic modeling guidelines is needed.</p>
        </sec>
      </sec>
      <sec>
        <title>Procedure</title>
        <p>Our workflow is depicted in <xref rid="figure1" ref-type="fig">Figure 1</xref>. To prepare data for analysis, we initiated a series of preprocessing steps, including removing numbers, punctuation, and parts of speech that would detract from the readability of our models, including articles, prepositions, and contractions. Once all data were processed and cleaned, we divided our grand corpus into yearly iterations to afford content comparisons between years (RQ1). We ran a TF-IDF across every year (ie, 2020, 2021, and 2022), then used k-means clustering with elbow scree plots to identify the optimal number of clusters per year. We then applied a PCA to visualize our 2020, 2021, and 2022 data along a vector map. Once data were visualized, we ran interpretation models to afford within-year (or within-cluster) comparisons, including to determine the extent that a natural experiment, such as the COVID-19 pandemic, affected yearly Dry January–related content (RQ2). For example, we used LDA to examine content within each cluster per given year. We used VADER to examine affect per cluster per year. We used the Botometer to determine average bot score per cluster per year. Last, to assess user engagement with Dry January content (RQ3), we took the average number of likes and retweets per cluster and ran correlations with other outcome variables of interest including VADER and Botometer scores.</p>
        <fig id="figure1" position="float">
          <label>Figure 1</label>
          <caption>
            <p>Study workflow detailing visualization and interpretation analyses per year. LDA: latent Dirichlet allocation; PCA: principal component analysis; TF-IDF: term frequency inverse document frequency; VADER: Valence Aware Dictionary and Sentiment Reasoner.</p>
          </caption>
          <graphic xlink:href="jmir_v24i11e40160_fig1.png" alt-version="no" mimetype="image" position="float" xlink:type="simple"/>
        </fig>
      </sec>
    </sec>
    <sec sec-type="results">
      <title>Results</title>
      <sec>
        <title>RQ1. What Themes Are Present Within a Corpus of Tweets About Dry January, and Is There Consistency in the Language Used to Discuss Dry January Across Multiple Years of Tweets (2020-2022)?</title>
        <p>First, we observed general consistency in topics over time. We used 2 measures to determine consistency of topics: (1) data shape (from the PCA) and (2) overlap in yearly topics (or repeating topics across each year of analysis). <xref rid="figure2" ref-type="fig">Figure 2</xref> provides a visualization of our data per year and model fit summaries; <xref ref-type="table" rid="table1">Table 1</xref> similarly provides general information for each year of data collection, topics per year and associated names, the number of tweets per cluster, engagement variables, and other indicators.</p>
        <fig id="figure2" position="float">
          <label>Figure 2</label>
          <caption>
            <p>Composite figure with principal component analysis (PCA) visualization by year with model fit: (A) 2020 Dry January Twitter dialogue, (B) 2021 Dry January Twitter dialogue, (C) 2022 Dry January Twitter dialogue, (D) elbow method graphs.</p>
          </caption>
          <graphic xlink:href="jmir_v24i11e40160_fig2.png" alt-version="no" mimetype="image" position="float" xlink:type="simple"/>
        </fig>
        <table-wrap position="float" id="table1">
          <label>Table 1</label>
          <caption>
            <p>Content cluster themes and associated summary statistics (n=222,917).</p>
          </caption>
          <table width="1000" cellpadding="5" cellspacing="0" border="1" rules="groups" frame="hsides">
            <col width="30"/>
            <col width="200"/>
            <col width="0"/>
            <col width="120"/>
            <col width="0"/>
            <col width="140"/>
            <col width="0"/>
            <col width="140"/>
            <col width="0"/>
            <col width="110"/>
            <col width="0"/>
            <col width="120"/>
            <col width="0"/>
            <col width="140"/>
            <thead>
              <tr valign="bottom">
                <td colspan="3">Year and topic</td>
                <td colspan="2">Results, n (%)<break/>  <break/>  </td>
                <td colspan="2">VADER<sup>a</sup>, mean<sup>b</sup></td>
                <td colspan="2">Retweets, mean<sup>c</sup></td>
                <td colspan="2">Likes, mean<sup>c</sup></td>
                <td colspan="2">Quotes, mean<sup>c</sup></td>
                <td>Botometer score<sup>d</sup></td>
              </tr>
            </thead>
            <tbody>
              <tr valign="top">
                <td colspan="14">
                  <bold>2020 (n=70,215)</bold>
                </td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>Sarcasm/humor</td>
                <td colspan="2">38,242 (54.5)</td>
                <td colspan="2">0.16</td>
                <td colspan="2">0.82</td>
                <td colspan="2">9.10</td>
                <td colspan="2">0.12</td>
                <td colspan="2">0.37</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>DJ<sup>e</sup> health benefits</td>
                <td colspan="2">5804 (8.3)</td>
                <td colspan="2">0.37</td>
                <td colspan="2">1.17</td>
                <td colspan="2">5.39</td>
                <td colspan="2">0.21</td>
                <td colspan="2">0.52</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>Perrier ad</td>
                <td colspan="2">1320 (1.9)</td>
                <td colspan="2">–0.93</td>
                <td colspan="2">0.00</td>
                <td colspan="2">0.12</td>
                <td colspan="2">0.01</td>
                <td colspan="2">0.88</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>Unclear/general</td>
                <td colspan="2">1458 (2.1)</td>
                <td colspan="2">0.03</td>
                <td colspan="2">0.32</td>
                <td colspan="2">4.28</td>
                <td colspan="2">0.07</td>
                <td colspan="2">0.37</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>DJ progress</td>
                <td colspan="2">3372 (4.8)</td>
                <td colspan="2">0.24</td>
                <td colspan="2">0.85</td>
                <td colspan="2">9.04</td>
                <td colspan="2">0.10</td>
                <td colspan="2">0.48</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>Perrier ad II</td>
                <td colspan="2">1334 (1.9)</td>
                <td colspan="2">0.93</td>
                <td colspan="2">0.00</td>
                <td colspan="2">0.13</td>
                <td colspan="2">0.01</td>
                <td colspan="2">0.88</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>DJ resources</td>
                <td colspan="2">16,390 (24.1)</td>
                <td colspan="2">0.36</td>
                <td colspan="2">0.77</td>
                <td colspan="2">4.18</td>
                <td colspan="2">0.10</td>
                <td colspan="2">0.44</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>Support &#38; engagement</td>
                <td colspan="2">1755 (2.5)</td>
                <td colspan="2">0.29</td>
                <td colspan="2">0.50</td>
                <td colspan="2">7.80</td>
                <td colspan="2">0.08</td>
                <td colspan="2">0.39</td>
              </tr>
              <tr valign="top">
                <td> </td>
                <td>Entire 2020 data set</td>
                <td colspan="2">N/A<sup>f</sup></td>
                <td colspan="2">0.18</td>
                <td colspan="2">0.55</td>
                <td colspan="2">5.01</td>
                <td colspan="2">0.01</td>
                <td colspan="2">0.54</td>
              </tr>
              <tr valign="top">
                <td colspan="14">
                  <bold>2021 (n=86,378)</bold>
                </td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>DJ nearly over</td>
                <td colspan="2">6190 (7.2)</td>
                <td colspan="2">0.2</td>
                <td colspan="2">0.72</td>
                <td colspan="2">12.39</td>
                <td colspan="2">0.17</td>
                <td colspan="2">0.49</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>Heineken 0.0. ad</td>
                <td colspan="2">953 (1.1)</td>
                <td colspan="2">0.61</td>
                <td colspan="2">0.007</td>
                <td colspan="2">0.07</td>
                <td colspan="2">0.003</td>
                <td colspan="2">0.9</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>DJ reflections</td>
                <td colspan="2">56,823 (65.8)</td>
                <td colspan="2">0.14</td>
                <td colspan="2">0.78</td>
                <td colspan="2">13.76</td>
                <td colspan="2">0.14</td>
                <td colspan="2">0.49</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>DJ resources</td>
                <td colspan="2">17,374 (20.1)</td>
                <td colspan="2">0.35</td>
                <td colspan="2">0.76</td>
                <td colspan="2">8.16</td>
                <td colspan="2">0.18</td>
                <td colspan="2">0.55</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>DJ &#38; pandemic</td>
                <td colspan="2">3305 (3.8)</td>
                <td colspan="2">0.19</td>
                <td colspan="2">0.455</td>
                <td colspan="2">13.98</td>
                <td colspan="2">0.11</td>
                <td colspan="2">0.47</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>DJ general topic</td>
                <td colspan="2">1733 (2.0)</td>
                <td colspan="2">0.02</td>
                <td colspan="2">2.8</td>
                <td colspan="2">29.32</td>
                <td colspan="2">0.27</td>
                <td colspan="2">0.44</td>
              </tr>
              <tr valign="top">
                <td> </td>
                <td>Entire 2021 data set</td>
                <td colspan="2">N/A</td>
                <td colspan="2">0.25</td>
                <td colspan="2">0.92</td>
                <td colspan="2">12.95</td>
                <td colspan="2">0.15</td>
                <td colspan="2">0.56</td>
              </tr>
              <tr valign="top">
                <td colspan="14">
                  <bold>2022 (n=66,324)</bold>
                </td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>Starting DJ</td>
                <td colspan="2">2242 (3.4)</td>
                <td colspan="2">0.24</td>
                <td colspan="2">1.03</td>
                <td colspan="2">16.81</td>
                <td colspan="2">0.27</td>
                <td colspan="2">0.5</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>Academic self-promotion</td>
                <td colspan="2">1254 (1.9)</td>
                <td colspan="2">0.533</td>
                <td colspan="2">0.02</td>
                <td colspan="2">0.04</td>
                <td colspan="2">0.005</td>
                <td colspan="2">0.82</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>DJ health benefits</td>
                <td colspan="2">42,894 (64.7)</td>
                <td colspan="2">0.17</td>
                <td colspan="2">0.88</td>
                <td colspan="2">14.03</td>
                <td colspan="2">0.13</td>
                <td colspan="2">0.52</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>Pre-DJ binge drinking</td>
                <td colspan="2">15,183 (22.9)</td>
                <td colspan="2">0.37</td>
                <td colspan="2">0.7</td>
                <td colspan="2">5.85</td>
                <td colspan="2">0.09</td>
                <td colspan="2">0.67</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>General DJ topic</td>
                <td colspan="2">1447 (2.2)</td>
                <td colspan="2">0.03</td>
                <td colspan="2">0.4</td>
                <td colspan="2">7.97</td>
                <td colspan="2">0.07</td>
                <td colspan="2">0.52</td>
              </tr>
              <tr valign="top">
                <td>
                  <break/>
                </td>
                <td>DJ participation &#38; outlook</td>
                <td colspan="2">3304 (5.0)</td>
                <td colspan="2">0.23</td>
                <td colspan="2">0.79</td>
                <td colspan="2">13.38</td>
                <td colspan="2">0.11</td>
                <td colspan="2">0.49</td>
              </tr>
              <tr valign="top">
                <td> </td>
                <td>Entire 2022 data set</td>
                <td colspan="2">N/A</td>
                <td colspan="2">0.26</td>
                <td colspan="2">0.64</td>
                <td colspan="2">9.6</td>
                <td colspan="2">0.11</td>
                <td colspan="2">0.59</td>
              </tr>
              <tr valign="top">
                <td colspan="3">Total</td>
                <td colspan="2">N/A</td>
                <td colspan="2">0.23</td>
                <td colspan="2">0.70</td>
                <td colspan="2">9.19</td>
                <td colspan="2">0.09</td>
                <td>0.56</td>
              </tr>
            </tbody>
          </table>
          <table-wrap-foot>
            <fn id="table1fn1">
              <p><sup>a</sup>VADER: Valence Aware Dictionary and Sentiment Reasoner.</p>
            </fn>
            <fn id="table1fn2">
              <p><sup>b</sup>Mean scores were derived from scores ranging from –.99 (high negative affect) to .99 (high positive affect).</p>
            </fn>
            <fn id="table1fn3">
              <p><sup>c</sup>A score of 1 indicates 1 retweet, like, or quote.</p>
            </fn>
            <fn id="table1fn4">
              <p><sup>d</sup>Botometer scores range from .01 (low bot account likelihood) to .90 (high bot account likelihood).</p>
            </fn>
            <fn id="table1fn5">
              <p><sup>e</sup>DJ: Dry January.</p>
            </fn>
            <fn id="table1fn6">
              <p><sup>f</sup>Not applicable.</p>
            </fn>
          </table-wrap-foot>
        </table-wrap>
        <p>Using a coding procedure outlined in the previous sections, 3 authors affiliated with this study manually named each cluster using a series of representative tweets. Language in representative tweets posted by individual users subsequently included as exemplar tweets was slightly modified to capture original sentiment while preserving anonymity. Per each year, we observed several similar topics that suggest relative consistency in Dry January content over time. These topics include: (1) a general Dry January topic (eg, <italic>“</italic>Dry January yes, or no?”), (2) Dry January resources (eg, “Have you considered our app to help you maintain your #DryJanuary Goals?”), (3) Dry January health benefits (eg, “Here’s what one alcohol-free month can do for your mind and body”), and (4) updates (positive and negative) related to Dry January progress (eg, “Well, I only lasted a week of Dry January before I drank!”). In 2 of the 3 years included for analysis, we also observed corporate ads targeting Dry January participants, though similar ads were not apparent in 2022.</p>
        <p>To support that yearly Dry January content was consistent, we also examined data shape (<xref rid="figure2" ref-type="fig">Figure 2</xref>). Indeed, our combined k-means and PCA approach demonstrates relative similarity and dissimilarity of clusters for each year of analysis. Clusters that are proximal contain similar content; clusters that are distal indicate dissimilar content. Though we acknowledge certain variation across each year, the data shape was relatively similar, which may indicate limited change in content over time. For example, in each year included for analysis, we observed 2 dominant clusters and several smaller clusters dispersed throughout the diagram. Additionally, for each year, we consistently observed at least 2 topics that were far removed and disconnected from the rest of the diagram. Topics, or clusters, that do not overlap with other clusters suggest pockets of conversation that are related to, but not necessarily embedded, within the larger conversation. A secondary explanation for consistent data shape may also be the cohesive theme of the grand corpus or subcorpora (ie, alcohol abstention during the month of January).</p>
      </sec>
      <sec>
        <title>RQ2. Do Unique Themes or Patterns Emerge in Dry January 2021 Tweets After the Onset of the COVID-19 Pandemic?</title>
        <p>Our findings also indicate that Dry January was affected by emerging news cycles, most notably the COVID-19 pandemic. In the 2020 subcorpora, for example, we did not observe any tweets related to COVID-19, which would not become prevalent in the United States and Europe until March the same year. However, in the following year, we observed 1 cluster containing humorous content about Dry January’s cancellation due to the ongoing global pandemic (eg,”Bro, how can we do Dry January during a pandemic?” and “#DryJanuary is officially CANCELLED”). We also observed a small portion of tweets related to the January 6, 2021, US Capitol insurrection, though this content was less prevalent than COVID-19–related tweets. We did not observe a similar cluster related to COVID-19, or similarly disruptive news cycles, during 2022. Yearly news cycle changes may also explain variation in yearly data shape.</p>
      </sec>
      <sec>
        <title>RQ3. How Does Tweet Composition (ie, Sentiment and Human-Authored vs Bot-Authored) Affect Engagement With Dry January Tweets?</title>
        <p>Tweet composition was associated with engagement, including number of likes, retweets, and quote-tweets per post. We used the Botometer and VADER sentiment analysis to test (1) whether bot-authored and human-authored posts had observed differences in engagement and (2) whether sentiment, which is calculated using the VADER lexicon, similarly affected tweet engagement.</p>
        <p>For each year included in our analysis, we observed at least one bot-dominant cluster or an otherwise automated account that posts prewritten content. Per year, bot-dominant clusters were typically comprised of ads, such as Perrier Water and Heineken 0.0 beer, and to a smaller extent, paid or free resources to promote Dry January adherence. Bot-dominant clusters also had fewer likes, retweets, or quote tweets compared with human-authored clusters. Similarly, bot-dominant clusters also had the highest observed positive affect, or greatest amount of positivity per post (eg, “Ready to crush Dry January...with Perrier in your hands you are going to #MakeDryFly!!”). By contrast, human-authored accounts typically had greater engagement and contained lower affect, or greater amount of negativity (eg, “Bro I’m gonna DIE if I have to do another week of Dry January. LOL”). We note that lower affect may reflect sarcasm, though more research on this area is needed.</p>
      </sec>
    </sec>
    <sec sec-type="discussion">
      <title>Discussion</title>
      <sec>
        <title>Principal Findings and Implications</title>
        <p>Our study characterized online content about Dry January, assessing trends, themes, and general attitudes toward the challenge. We used NLP tools to analyze and visualize a yearly series of tweets related to Dry January over the course of 3 years of participation. Our findings highlight that there is consistency in discussion themes about Dry January across multiple years of tweets, yet we were still able to detect unique themes that emerged in 2021 in response to the COVID-19 global pandemic. Additionally, tweet composition, or whether a tweet was bot-authored or human-authored and the sentiment of the tweet, was associated with user engagement (number of likes, retweets, and quote-tweets).</p>
        <p>In the content cluster analysis of the corpus of Dry January tweets, several common themes emerged across multiple years of Dry January participation. For example, the promotion of Dry January resources—such as blogs with tips for help with sustaining Dry January efforts, mobile applications facilitating additional support and accountability, and recipes for nonalcoholic “mocktails”—was a consistent theme each year. Additionally, we observed a cluster associated with Dry January health benefits (eg, drinking reductions, weight loss, healthier dietary choices, reflecting on relationship with alcohol). These findings are consistent with prior work on Dry January that similarly highlighted reductions in alcohol consumption and weight loss as Dry January benefits, in addition to increases in alcohol refusal skills, saving money, improved sleep, increased energy, and enhanced psychological well-being [<xref ref-type="bibr" rid="ref5">5</xref>,<xref ref-type="bibr" rid="ref7">7</xref>-<xref ref-type="bibr" rid="ref9">9</xref>]. Finally, a topic related to sharing about Dry January progress emerged across multiple years of data (eg, no desire to participate in Dry January, intention to participate in Dry January, failed attempts to abstain during Dry January, successful ongoing attempts, successful completion of Dry January). Although some tweets in this cluster referenced successful Dry January experiences and positive associations with these experiences, a large number of these tweets used humor and sarcasm to make light of Dry January participation and voiced an overall lack of desire to participate in the temporary abstinence initiative. This finding is in line with prior work examining alcohol-related content on social media platforms, such as Twitter and TikTok [<xref ref-type="bibr" rid="ref25">25</xref>,<xref ref-type="bibr" rid="ref26">26</xref>,<xref ref-type="bibr" rid="ref59">59</xref>]; the vast majority of alcohol-related posts on these social media platforms portray drinking in a positive manner and often depict hazardous drinking behaviors, such as intoxication and blacking out, in a favorable manner. Similarly, alcohol-related negative consequences are rarely portrayed in alcohol-related social media posts, and when such portrayals are present, they are often depicted in a humorous manner that serves to downplay the severity of alcohol-related problems [<xref ref-type="bibr" rid="ref25">25</xref>,<xref ref-type="bibr" rid="ref59">59</xref>].</p>
        <p>Content cluster analysis also detected unique themes related to Dry January across years, most notably a cluster of tweets related to Dry January participation in the context of the ongoing COVID-19 global pandemic during January 2021. Many of these tweets referenced individuals experiencing increased difficulty or a lack of desire to participate in Dry January in the context of the pandemic and social distancing restrictions and increased psychological stressors. Yet, others made reference to having an easier time abstaining during January due to the lack of access to social drinking activities. Humor was commonly used to make light of Dry January in the context of the pandemic. Subthemes within this cluster of tweets were consistent with prior research on alcohol consumption during the peak of the pandemic [<xref ref-type="bibr" rid="ref60">60</xref>,<xref ref-type="bibr" rid="ref61">61</xref>]. In addition to millions of COVID-19–related deaths, the COVID-19 pandemic has been associated with increased psychological stressors due to social isolation and higher unemployment rates, among numerous other factors [<xref ref-type="bibr" rid="ref60">60</xref>,<xref ref-type="bibr" rid="ref61">61</xref>]. Many have coped with COVID-19 pandemic stressors in the form of self-medication by increasing alcohol consumption [<xref ref-type="bibr" rid="ref60">60</xref>,<xref ref-type="bibr" rid="ref61">61</xref>]. Real-time infoveillance of social media posts may prove a valuable means through which to complement health behavior surveillance efforts and to detect public discourse and communication about unique health needs in response to big events, such as coping with the increased psychological stressors associated with the COVID-19 pandemic and how this may negatively impact efforts to quit or cut down on drinking [<xref ref-type="bibr" rid="ref62">62</xref>].</p>
        <p>Finally, we found that tweet composition, most namely whether a tweet was bot-authored versus human-authored affected online engagement with posts. That is to say, bot-dominant clusters (eg, Perrier and Heineken 0.0 promotional efforts) had fewer likes, retweets, and quote-tweets compared to primarily human-authored clusters. This finding has implications for public health messaging and intervention on social media platforms. Although there may be public health benefits from the development and facilitation of social bot-oriented online interventions [<xref ref-type="bibr" rid="ref63">63</xref>], investigation is warranted into how best to tailor such intervention efforts to enhance engagement, as it appears many individuals in this study largely ignore posts from automated accounts with prewritten content. That said, without knowing the goals or intended outcomes of the bot creators (ie, generating content vs sharing content or raising awareness vs generating engagement), we are unable to determine the effectiveness of social bot presence in Dry January content on Twitter. Our findings do support the presence of social bots and their potential to create, share, and engage with online content.</p>
      </sec>
      <sec>
        <title>Limitations</title>
        <p>This work is subject to limitations we hope to address in future work. First, although a combined k-means and PCA approach has been extensively validated as an effective way to analyze and visualize abundant social media content, this approach is exploratory and relies on unsupervised algorithms to arrive at findings. As such, there is a possibility that a small proportion of tweets may have been miscategorized by the algorithms. Second, given financial limitations with the Botometer API, we were unable to calculate Botometer scores for all tweets included in the analysis. Instead, we relied on generalizing the Botometer scores from a random subsample of 500 tweets per cluster. It is possible that a full Botometer analysis with the entire sample would alter our findings slightly, particularly for larger clusters comprised of tens of thousands of tweets; however, significant cost barriers associated with the Botometer API prohibited access to a full analysis of tweets. Finally, we also acknowledge that we did not perform a full qualitative analysis with these data. Although we maintain our blinded coding procedure to name clusters was sufficient to determine cluster names, there is also a possibility that a full review of all tweets in a given cluster would yield marginally different cluster names. Through the limitations outlined, we offer several compelling research opportunities to continue this study. For example, a comparative study contrasting our findings from those generated using supervised NLP algorithms, for example the Sentence Bidirectional Encoder from Transformers (S-BERT), could help validate our findings particularly if there is strong overlap across analyses.</p>
      </sec>
      <sec>
        <title>Conclusions</title>
        <p>We explored themes within and across 3 separate years of Twitter posts about the Dry January temporary alcohol abstinence challenge. Although there was overlap in themes across multiple years of tweets, unique themes related to individuals’ experiences with alcohol during the midst of the COVID-19 global pandemic were detected in the corpus of tweets from 2021. Findings underscore the utility for using large-scale social media, such as discussions on Twitter, to study drinking reduction attempts and to monitor the ongoing dynamic needs of persons contemplating, preparing for, or actively pursuing attempts to quit or cut down on their drinking.</p>
      </sec>
    </sec>
  </body>
  <back>
    <app-group/>
    <glossary>
      <title>Abbreviations</title>
      <def-list>
        <def-item>
          <term id="abb1">API</term>
          <def>
            <p>application programming interface</p>
          </def>
        </def-item>
        <def-item>
          <term id="abb2">DJ</term>
          <def>
            <p>Dry January</p>
          </def>
        </def-item>
        <def-item>
          <term id="abb3">LDA</term>
          <def>
            <p>latent Dirichlet allocation</p>
          </def>
        </def-item>
        <def-item>
          <term id="abb4">NLP</term>
          <def>
            <p>natural language processing</p>
          </def>
        </def-item>
        <def-item>
          <term id="abb5">PCA</term>
          <def>
            <p>principal component analysis</p>
          </def>
        </def-item>
        <def-item>
          <term id="abb6">RQ</term>
          <def>
            <p>research question</p>
          </def>
        </def-item>
        <def-item>
          <term id="abb7">S-BERT</term>
          <def>
            <p>Sentence Bidirectional Encoder from Transformers</p>
          </def>
        </def-item>
        <def-item>
          <term id="abb8">TF-IDF</term>
          <def>
            <p>term frequency inverse document frequency</p>
          </def>
        </def-item>
        <def-item>
          <term id="abb9">VADER</term>
          <def>
            <p>Valence Aware Dictionary and Sentiment Reasoner</p>
          </def>
        </def-item>
      </def-list>
    </glossary>
    <ack>
      <p>AMR was supported by the National Institute on Alcohol Abuse and Alcoholism of the National Institutes of Health under award number K01AA030614. HCL was supported by the National Institute on Drug Abuse of the National Institutes of Health under award number R01DA049154. PMM was supported by the National Cancer Institute of the National Institutes of Health under award number R01CA229324. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.</p>
    </ack>
    <fn-group>
      <fn fn-type="con">
        <p>AMR, DV, SCC, AEB, HCL, and PMM conceptualized and designed the study. AMR, DV, SCC, and BNM contributed to writing the initial draft of the manuscript. DV performed the data analysis for this study with support from SCC. PMM, AEB, and HCL provided mentorship throughout and helped with interpretation of findings and critical reviews of the manuscript. All authors contributed to and have approved the final manuscript.</p>
      </fn>
      <fn fn-type="conflict">
        <p>None declared.</p>
      </fn>
    </fn-group>
    <ref-list>
      <ref id="ref1">
        <label>1</label>
        <nlm-citation citation-type="web">
          <article-title>The Dry January story</article-title>
          <source>Alcohol Change UK</source>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://alcoholchange.org.uk/get-involved/campaigns/dry-january/about-dry-january/the-dry-january-story">https://alcoholchange.org.uk/get-involved/campaigns/dry-january/about-dry-january/the-dry-january-story</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref2">
        <label>2</label>
        <nlm-citation citation-type="web">
          <article-title>Why do Dry January?</article-title>
          <source>Alcohol Change UK</source>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://alcoholchange.org.uk/get-involved/campaigns/dry-january/why-do-dry-january-1/why-do-dry-january">https://alcoholchange.org.uk/get-involved/campaigns/dry-january/why-do-dry-january-1/why-do-dry-january</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref3">
        <label>3</label>
        <nlm-citation citation-type="web">
          <article-title>Take part in Dry January</article-title>
          <source>Alcohol Change UK</source>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://alcoholchange.org.uk/get-involved/campaigns/dry-january/sign-up-for-dry-january">https://alcoholchange.org.uk/get-involved/campaigns/dry-january/sign-up-for-dry-january</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref4">
        <label>4</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Christakis</surname>
              <given-names>NA</given-names>
            </name>
            <name name-style="western">
              <surname>Fowler</surname>
              <given-names>JH</given-names>
            </name>
          </person-group>
          <article-title>Social contagion theory: examining dynamic social networks and human behavior</article-title>
          <source>Stat Med</source>
          <year>2013</year>
          <month>02</month>
          <day>20</day>
          <volume>32</volume>
          <issue>4</issue>
          <fpage>556</fpage>
          <lpage>77</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/22711416"/>
          </comment>
          <pub-id pub-id-type="doi">10.1002/sim.5408</pub-id>
          <pub-id pub-id-type="medline">22711416</pub-id>
          <pub-id pub-id-type="pmcid">PMC3830455</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref5">
        <label>5</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>de Visser</surname>
              <given-names>RO</given-names>
            </name>
            <name name-style="western">
              <surname>Nicholls</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Temporary abstinence during Dry January: predictors of success; impact on well-being and self-efficacy</article-title>
          <source>Psychol Health</source>
          <year>2020</year>
          <month>11</month>
          <day>27</day>
          <volume>35</volume>
          <issue>11</issue>
          <fpage>1293</fpage>
          <lpage>1305</lpage>
          <pub-id pub-id-type="doi">10.1080/08870446.2020.1743840</pub-id>
          <pub-id pub-id-type="medline">32216557</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref6">
        <label>6</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Yeomans</surname>
              <given-names>H</given-names>
            </name>
          </person-group>
          <article-title>New Year, New You: a qualitative study of Dry January, self-formation and positive regulation</article-title>
          <source>Drugs: Education, Prevention and Policy</source>
          <year>2018</year>
          <month>12</month>
          <day>31</day>
          <volume>26</volume>
          <issue>6</issue>
          <fpage>460</fpage>
          <lpage>468</lpage>
          <pub-id pub-id-type="doi">10.1080/09687637.2018.1534944</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref7">
        <label>7</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>de Visser</surname>
              <given-names>RO</given-names>
            </name>
            <name name-style="western">
              <surname>Robinson</surname>
              <given-names>E</given-names>
            </name>
            <name name-style="western">
              <surname>Bond</surname>
              <given-names>R</given-names>
            </name>
          </person-group>
          <article-title>Voluntary temporary abstinence from alcohol during "Dry January" and subsequent alcohol use</article-title>
          <source>Health Psychol</source>
          <year>2016</year>
          <month>03</month>
          <volume>35</volume>
          <issue>3</issue>
          <fpage>281</fpage>
          <lpage>9</lpage>
          <pub-id pub-id-type="doi">10.1037/hea0000297</pub-id>
          <pub-id pub-id-type="medline">26690637</pub-id>
          <pub-id pub-id-type="pii">2015-57039-001</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref8">
        <label>8</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>de Visser</surname>
              <given-names>RO</given-names>
            </name>
            <name name-style="western">
              <surname>Robinson</surname>
              <given-names>E</given-names>
            </name>
            <name name-style="western">
              <surname>Smith</surname>
              <given-names>T</given-names>
            </name>
            <name name-style="western">
              <surname>Cass</surname>
              <given-names>G</given-names>
            </name>
            <name name-style="western">
              <surname>Walmsley</surname>
              <given-names>M</given-names>
            </name>
          </person-group>
          <article-title>The growth of 'Dry January': promoting participation and the benefits of participation</article-title>
          <source>Eur J Public Health</source>
          <year>2017</year>
          <month>10</month>
          <day>01</day>
          <volume>27</volume>
          <issue>5</issue>
          <fpage>929</fpage>
          <lpage>931</lpage>
          <pub-id pub-id-type="doi">10.1093/eurpub/ckx124</pub-id>
          <pub-id pub-id-type="medline">28957493</pub-id>
          <pub-id pub-id-type="pii">4209886</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref9">
        <label>9</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>de Visser</surname>
              <given-names>RO</given-names>
            </name>
            <name name-style="western">
              <surname>Piper</surname>
              <given-names>R</given-names>
            </name>
          </person-group>
          <article-title>Short- and longer-term benefits of temporary alcohol abstinence during 'Dry January' are not also observed among adult drinkers in the general population: prospective cohort study</article-title>
          <source>Alcohol Alcohol</source>
          <year>2020</year>
          <month>06</month>
          <day>25</day>
          <volume>55</volume>
          <issue>4</issue>
          <fpage>433</fpage>
          <lpage>438</lpage>
          <pub-id pub-id-type="doi">10.1093/alcalc/agaa025</pub-id>
          <pub-id pub-id-type="medline">32391879</pub-id>
          <pub-id pub-id-type="pii">5835641</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref10">
        <label>10</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Case</surname>
              <given-names>P</given-names>
            </name>
            <name name-style="western">
              <surname>Angus</surname>
              <given-names>C</given-names>
            </name>
            <name name-style="western">
              <surname>De Vocht</surname>
              <given-names>F</given-names>
            </name>
            <name name-style="western">
              <surname>Holmes</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Michie</surname>
              <given-names>S</given-names>
            </name>
            <name name-style="western">
              <surname>Brown</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Has the increased participation in the national campaign 'Dry January' been associated with cutting down alcohol consumption in England?</article-title>
          <source>Drug Alcohol Depend</source>
          <year>2021</year>
          <month>10</month>
          <day>01</day>
          <volume>227</volume>
          <fpage>108938</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://linkinghub.elsevier.com/retrieve/pii/S0376-8716(21)00433-6"/>
          </comment>
          <pub-id pub-id-type="doi">10.1016/j.drugalcdep.2021.108938</pub-id>
          <pub-id pub-id-type="medline">34392050</pub-id>
          <pub-id pub-id-type="pii">S0376-8716(21)00433-6</pub-id>
          <pub-id pub-id-type="pmcid">PMC8504198</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref11">
        <label>11</label>
        <nlm-citation citation-type="web">
          <article-title>Press release: 5 million people plan to do Dry January 2021, up from 3.9 million in 2020</article-title>
          <source>Alcohol Change UK</source>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://alcoholchange.org.uk/blog/2020/press-release-6-5-million-people-plan-to-do-dry-january-2021-up-from-3-9-million-in-2020">https://alcoholchange.org.uk/blog/2020/press-release-6-5-million-people-plan-to-do-dry-january-2021-up-from-3-9-million-in-2020</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref12">
        <label>12</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>de Ternay</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Leblanc</surname>
              <given-names>P</given-names>
            </name>
            <name name-style="western">
              <surname>Michel</surname>
              <given-names>P</given-names>
            </name>
            <name name-style="western">
              <surname>Benyamina</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Naassila</surname>
              <given-names>M</given-names>
            </name>
            <name name-style="western">
              <surname>Rolland</surname>
              <given-names>B</given-names>
            </name>
          </person-group>
          <article-title>One-month alcohol abstinence national campaigns: a scoping review of the harm reduction benefits</article-title>
          <source>Harm Reduct J</source>
          <year>2022</year>
          <month>03</month>
          <day>04</day>
          <volume>19</volume>
          <issue>1</issue>
          <fpage>24</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://harmreductionjournal.biomedcentral.com/articles/10.1186/s12954-022-00603-x"/>
          </comment>
          <pub-id pub-id-type="doi">10.1186/s12954-022-00603-x</pub-id>
          <pub-id pub-id-type="medline">35246148</pub-id>
          <pub-id pub-id-type="pii">10.1186/s12954-022-00603-x</pub-id>
          <pub-id pub-id-type="pmcid">PMC8895623</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref13">
        <label>13</label>
        <nlm-citation citation-type="web">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Sheffey</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Lalljee</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Sober-curious Millennials and Gen Z are driving Dry January's comeback after a stressful 2021</article-title>
          <source>Insider</source>
          <year>2022</year>
          <month>1</month>
          <day>5</day>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.businessinsider.com/dry-january-sober-curious-taking-break-from-drinking-stress-2021-12">https://www.businessinsider.com/dry-january-sober-curious-taking-break-from-drinking-stress-2021-12</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref14">
        <label>14</label>
        <nlm-citation citation-type="web">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Moquin</surname>
              <given-names>E</given-names>
            </name>
          </person-group>
          <article-title>Dry January movement grows in 2022, but for many it's more damp than dry</article-title>
          <source>Morning Consult</source>
          <year>2022</year>
          <month>1</month>
          <day>10</day>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://morningconsult.com/2022/01/10/dry-january-movement-grows-in-2022/">https://morningconsult.com/2022/01/10/dry-january-movement-grows-in-2022/</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref15">
        <label>15</label>
        <nlm-citation citation-type="web">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Asmelash</surname>
              <given-names>L</given-names>
            </name>
          </person-group>
          <article-title>How Dry January’s continued presence reflects society’s evolving – and divisive – relationship with alcohol</article-title>
          <source>CNN</source>
          <year>2022</year>
          <month>1</month>
          <day>19</day>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.cnn.com/2022/01/19/us/dry-january-less-people-drinking-wellness-cec/index.html">https://www.cnn.com/2022/01/19/us/dry-january-less-people-drinking-wellness-cec/index.html</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref16">
        <label>16</label>
        <nlm-citation citation-type="web">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Furnari</surname>
              <given-names>C</given-names>
            </name>
          </person-group>
          <article-title>New Surveys indicate increasing interest in Dry January</article-title>
          <source>Forbes</source>
          <year>2021</year>
          <month>1</month>
          <day>11</day>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.forbes.com/sites/chrisfurnari/2021/01/11/new-surveys-indicate-increasing-interest-in-dry-january/?sh=22f87caf6f57">https://www.forbes.com/sites/chrisfurnari/2021/01/11/new-surveys-indicate-increasing-interest-in-dry-january/?sh=22f87caf6f57</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref17">
        <label>17</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Miller</surname>
              <given-names>M</given-names>
            </name>
            <name name-style="western">
              <surname>Pettigrew</surname>
              <given-names>S</given-names>
            </name>
            <name name-style="western">
              <surname>Wright</surname>
              <given-names>CJC</given-names>
            </name>
          </person-group>
          <article-title>Zero-alcohol beverages: Harm-minimisation tool or gateway drink?</article-title>
          <source>Drug Alcohol Rev</source>
          <year>2022</year>
          <month>03</month>
          <day>09</day>
          <volume>41</volume>
          <issue>3</issue>
          <fpage>546</fpage>
          <lpage>549</lpage>
          <pub-id pub-id-type="doi">10.1111/dar.13359</pub-id>
          <pub-id pub-id-type="medline">34370881</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref18">
        <label>18</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Eysenbach</surname>
              <given-names>G</given-names>
            </name>
          </person-group>
          <article-title>Infodemiology and infoveillance: framework for an emerging set of public health informatics methods to analyze search, communication and publication behavior on the Internet</article-title>
          <source>J Med Internet Res</source>
          <year>2009</year>
          <month>03</month>
          <day>27</day>
          <volume>11</volume>
          <issue>1</issue>
          <fpage>e11</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.jmir.org/2009/1/e11/"/>
          </comment>
          <pub-id pub-id-type="doi">10.2196/jmir.1157</pub-id>
          <pub-id pub-id-type="medline">19329408</pub-id>
          <pub-id pub-id-type="pii">v11i1e11</pub-id>
          <pub-id pub-id-type="pmcid">PMC2762766</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref19">
        <label>19</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Eysenbach</surname>
              <given-names>G</given-names>
            </name>
          </person-group>
          <article-title>Infodemiology and infoveillance tracking online health information and cyberbehavior for public health</article-title>
          <source>Am J Prev Med</source>
          <year>2011</year>
          <month>05</month>
          <volume>40</volume>
          <issue>5 Suppl 2</issue>
          <fpage>S154</fpage>
          <lpage>8</lpage>
          <pub-id pub-id-type="doi">10.1016/j.amepre.2011.02.006</pub-id>
          <pub-id pub-id-type="medline">21521589</pub-id>
          <pub-id pub-id-type="pii">S0749-3797(11)00088-2</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref20">
        <label>20</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Mackey</surname>
              <given-names>T</given-names>
            </name>
            <name name-style="western">
              <surname>Baur</surname>
              <given-names>C</given-names>
            </name>
            <name name-style="western">
              <surname>Eysenbach</surname>
              <given-names>G</given-names>
            </name>
          </person-group>
          <article-title>Advancing infodemiology in a digital intensive era</article-title>
          <source>JMIR Infodemiology</source>
          <year>2022</year>
          <month>2</month>
          <day>14</day>
          <volume>2</volume>
          <issue>1</issue>
          <fpage>e37115</fpage>
          <pub-id pub-id-type="doi">10.2196/37115</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref21">
        <label>21</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Mavragani</surname>
              <given-names>A</given-names>
            </name>
          </person-group>
          <article-title>Infodemiology and infoveillance: scoping review</article-title>
          <source>J Med Internet Res</source>
          <year>2020</year>
          <month>04</month>
          <day>28</day>
          <volume>22</volume>
          <issue>4</issue>
          <fpage>e16206</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.jmir.org/2020/4/e16206/"/>
          </comment>
          <pub-id pub-id-type="doi">10.2196/16206</pub-id>
          <pub-id pub-id-type="medline">32310818</pub-id>
          <pub-id pub-id-type="pii">v22i4e16206</pub-id>
          <pub-id pub-id-type="pmcid">PMC7189791</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref22">
        <label>22</label>
        <nlm-citation citation-type="web">
          <article-title>Social media fact sheet</article-title>
          <source>Pew Research Center</source>
          <year>2021</year>
          <month>04</month>
          <day>07</day>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.pewresearch.org/internet/fact-sheet/social-media/">https://www.pewresearch.org/internet/fact-sheet/social-media/</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref23">
        <label>23</label>
        <nlm-citation citation-type="web">
          <article-title>Majority of adults look online for health information</article-title>
          <source>Pew Research Center</source>
          <year>2013</year>
          <month>02</month>
          <day>01</day>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.pewresearch.org/fact-tank/2013/02/01/majority-of-adults-look-online-for-health-information/">https://www.pewresearch.org/fact-tank/2013/02/01/majority-of-adults-look-online-for-health-information/</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref24">
        <label>24</label>
        <nlm-citation citation-type="web">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Shearer</surname>
              <given-names>e</given-names>
            </name>
            <name name-style="western">
              <surname>Mitchell</surname>
              <given-names>A</given-names>
            </name>
          </person-group>
          <article-title>News Use Across Social Media Platforms in 2020</article-title>
          <source>Pew Research Center</source>
          <year>2021</year>
          <month>1</month>
          <day>12</day>
          <access-date>2022-11-13</access-date>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.journalism.org/2021/01/12/news-use-across-social-media-platforms-in-2020/">https://www.journalism.org/2021/01/12/news-use-across-social-media-platforms-in-2020/</ext-link>
          </comment>
        </nlm-citation>
      </ref>
      <ref id="ref25">
        <label>25</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Cavazos-Rehg</surname>
              <given-names>PA</given-names>
            </name>
            <name name-style="western">
              <surname>Krauss</surname>
              <given-names>MJ</given-names>
            </name>
            <name name-style="western">
              <surname>Sowles</surname>
              <given-names>SJ</given-names>
            </name>
            <name name-style="western">
              <surname>Bierut</surname>
              <given-names>LJ</given-names>
            </name>
          </person-group>
          <article-title>"Hey Everyone, I'm Drunk." An evaluation of drinking-related Twitter chatter</article-title>
          <source>J Stud Alcohol Drugs</source>
          <year>2015</year>
          <month>07</month>
          <volume>76</volume>
          <issue>4</issue>
          <fpage>635</fpage>
          <lpage>43</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/26098041"/>
          </comment>
          <pub-id pub-id-type="doi">10.15288/jsad.2015.76.635</pub-id>
          <pub-id pub-id-type="medline">26098041</pub-id>
          <pub-id pub-id-type="pmcid">PMC4495081</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref26">
        <label>26</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Riordan</surname>
              <given-names>BC</given-names>
            </name>
            <name name-style="western">
              <surname>Merrill</surname>
              <given-names>JE</given-names>
            </name>
            <name name-style="western">
              <surname>Ward</surname>
              <given-names>RM</given-names>
            </name>
          </person-group>
          <article-title>"Can't Wait to Blackout Tonight": An analysis of the motives to drink to blackout expressed on Twitter</article-title>
          <source>Alcohol Clin Exp Res</source>
          <year>2019</year>
          <month>08</month>
          <day>10</day>
          <volume>43</volume>
          <issue>8</issue>
          <fpage>1769</fpage>
          <lpage>1776</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/31373703"/>
          </comment>
          <pub-id pub-id-type="doi">10.1111/acer.14132</pub-id>
          <pub-id pub-id-type="medline">31373703</pub-id>
          <pub-id pub-id-type="pmcid">PMC6684310</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref27">
        <label>27</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Russell</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Colditz</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Barry</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Davis</surname>
              <given-names>RE</given-names>
            </name>
            <name name-style="western">
              <surname>Shields</surname>
              <given-names>S</given-names>
            </name>
            <name name-style="western">
              <surname>Ortega</surname>
              <given-names>JM</given-names>
            </name>
            <name name-style="western">
              <surname>Primack</surname>
              <given-names>B</given-names>
            </name>
          </person-group>
          <article-title>Analyzing Twitter chatter about tobacco use within intoxication-related contexts of alcohol use: "Can Someone Tell Me Why Nicotine is So Fire When You're Drunk?"</article-title>
          <source>Nicotine Tob Res</source>
          <year>2022</year>
          <month>07</month>
          <day>13</day>
          <volume>24</volume>
          <issue>8</issue>
          <fpage>1193</fpage>
          <lpage>1200</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/34562100"/>
          </comment>
          <pub-id pub-id-type="doi">10.1093/ntr/ntab195</pub-id>
          <pub-id pub-id-type="medline">34562100</pub-id>
          <pub-id pub-id-type="pii">6375364</pub-id>
          <pub-id pub-id-type="pmcid">PMC9278832</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref28">
        <label>28</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Ward</surname>
              <given-names>RM</given-names>
            </name>
            <name name-style="western">
              <surname>Riordan</surname>
              <given-names>BC</given-names>
            </name>
            <name name-style="western">
              <surname>Merrill</surname>
              <given-names>JE</given-names>
            </name>
            <name name-style="western">
              <surname>Raubenheimer</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Describing the impact of the COVID-19 pandemic on alcohol-induced blackout tweets</article-title>
          <source>Drug Alcohol Rev</source>
          <year>2021</year>
          <month>02</month>
          <day>06</day>
          <volume>40</volume>
          <issue>2</issue>
          <fpage>192</fpage>
          <lpage>195</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/33020967"/>
          </comment>
          <pub-id pub-id-type="doi">10.1111/dar.13186</pub-id>
          <pub-id pub-id-type="medline">33020967</pub-id>
          <pub-id pub-id-type="pmcid">PMC7675321</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref29">
        <label>29</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Allem</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Dharmapuri</surname>
              <given-names>L</given-names>
            </name>
            <name name-style="western">
              <surname>Leventhal</surname>
              <given-names>AM</given-names>
            </name>
            <name name-style="western">
              <surname>Unger</surname>
              <given-names>JB</given-names>
            </name>
            <name name-style="western">
              <surname>Boley Cruz</surname>
              <given-names>T</given-names>
            </name>
          </person-group>
          <article-title>Hookah-related posts to Twitter from 2017 to 2018: thematic analysis</article-title>
          <source>J Med Internet Res</source>
          <year>2018</year>
          <month>11</month>
          <day>19</day>
          <volume>20</volume>
          <issue>11</issue>
          <fpage>e11669</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.jmir.org/2018/11/e11669/"/>
          </comment>
          <pub-id pub-id-type="doi">10.2196/11669</pub-id>
          <pub-id pub-id-type="medline">30455162</pub-id>
          <pub-id pub-id-type="pii">v20i11e11669</pub-id>
          <pub-id pub-id-type="pmcid">PMC6277830</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref30">
        <label>30</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Sidani</surname>
              <given-names>JE</given-names>
            </name>
            <name name-style="western">
              <surname>Colditz</surname>
              <given-names>JB</given-names>
            </name>
            <name name-style="western">
              <surname>Barrett</surname>
              <given-names>EL</given-names>
            </name>
            <name name-style="western">
              <surname>Shensa</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Chu</surname>
              <given-names>K</given-names>
            </name>
            <name name-style="western">
              <surname>James</surname>
              <given-names>AE</given-names>
            </name>
            <name name-style="western">
              <surname>Primack</surname>
              <given-names>BA</given-names>
            </name>
          </person-group>
          <article-title>I wake up and hit the JUUL: analyzing Twitter for JUUL nicotine effects and dependence</article-title>
          <source>Drug and Alcohol Dependence</source>
          <year>2019</year>
          <month>11</month>
          <volume>204</volume>
          <fpage>107500</fpage>
          <pub-id pub-id-type="doi">10.1016/J.DRUGALCDEP.2019.06.005</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref31">
        <label>31</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Sidani</surname>
              <given-names>JE</given-names>
            </name>
            <name name-style="western">
              <surname>Colditz</surname>
              <given-names>JB</given-names>
            </name>
            <name name-style="western">
              <surname>Barrett</surname>
              <given-names>EL</given-names>
            </name>
            <name name-style="western">
              <surname>Chu</surname>
              <given-names>K</given-names>
            </name>
            <name name-style="western">
              <surname>James</surname>
              <given-names>AE</given-names>
            </name>
            <name name-style="western">
              <surname>Primack</surname>
              <given-names>BA</given-names>
            </name>
          </person-group>
          <article-title>JUUL on Twitter: analyzing tweets about use of a new nicotine delivery system</article-title>
          <source>J Sch Health</source>
          <year>2020</year>
          <month>02</month>
          <day>11</day>
          <volume>90</volume>
          <issue>2</issue>
          <fpage>135</fpage>
          <lpage>142</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/31828791"/>
          </comment>
          <pub-id pub-id-type="doi">10.1111/josh.12858</pub-id>
          <pub-id pub-id-type="medline">31828791</pub-id>
          <pub-id pub-id-type="pmcid">PMC7034811</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref32">
        <label>32</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Unger</surname>
              <given-names>JB</given-names>
            </name>
            <name name-style="western">
              <surname>Rogers</surname>
              <given-names>C</given-names>
            </name>
            <name name-style="western">
              <surname>Barrington-Trimis</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Majmundar</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Sussman</surname>
              <given-names>S</given-names>
            </name>
            <name name-style="western">
              <surname>Allem</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Soto</surname>
              <given-names>DW</given-names>
            </name>
            <name name-style="western">
              <surname>Cruz</surname>
              <given-names>TB</given-names>
            </name>
          </person-group>
          <article-title>"I'm using cigarettes to quit JUUL": An analysis of Twitter posts about JUUL cessation</article-title>
          <source>Addict Behav Rep</source>
          <year>2020</year>
          <month>12</month>
          <volume>12</volume>
          <fpage>100286</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://linkinghub.elsevier.com/retrieve/pii/S2352-8532(20)30101-2"/>
          </comment>
          <pub-id pub-id-type="doi">10.1016/j.abrep.2020.100286</pub-id>
          <pub-id pub-id-type="medline">32637562</pub-id>
          <pub-id pub-id-type="pii">S2352-8532(20)30101-2</pub-id>
          <pub-id pub-id-type="pmcid">PMC7330876</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref33">
        <label>33</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Allem</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Escobedo</surname>
              <given-names>P</given-names>
            </name>
            <name name-style="western">
              <surname>Dharmapuri</surname>
              <given-names>L</given-names>
            </name>
          </person-group>
          <article-title>Cannabis surveillance with Twitter data: emerging topics and social bots</article-title>
          <source>Am J Public Health</source>
          <year>2020</year>
          <month>03</month>
          <volume>110</volume>
          <issue>3</issue>
          <fpage>357</fpage>
          <lpage>362</lpage>
          <pub-id pub-id-type="doi">10.2105/ajph.2019.305461</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref34">
        <label>34</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Kalyanam</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Katsuki</surname>
              <given-names>T</given-names>
            </name>
            <name name-style="western">
              <surname>R G Lanckriet</surname>
              <given-names>G</given-names>
            </name>
            <name name-style="western">
              <surname>Mackey</surname>
              <given-names>TK</given-names>
            </name>
          </person-group>
          <article-title>Exploring trends of nonmedical use of prescription drugs and polydrug abuse in the Twittersphere using unsupervised machine learning</article-title>
          <source>Addict Behav</source>
          <year>2017</year>
          <month>02</month>
          <volume>65</volume>
          <fpage>289</fpage>
          <lpage>295</lpage>
          <pub-id pub-id-type="doi">10.1016/j.addbeh.2016.08.019</pub-id>
          <pub-id pub-id-type="medline">27568339</pub-id>
          <pub-id pub-id-type="pii">S0306-4603(16)30299-4</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref35">
        <label>35</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Budenz</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Klassen</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Purtle</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Yom Tov</surname>
              <given-names>E</given-names>
            </name>
            <name name-style="western">
              <surname>Yudell</surname>
              <given-names>M</given-names>
            </name>
            <name name-style="western">
              <surname>Massey</surname>
              <given-names>P</given-names>
            </name>
          </person-group>
          <article-title>Mental illness and bipolar disorder on Twitter: implications for stigma and social support</article-title>
          <source>J Ment Health</source>
          <year>2020</year>
          <month>04</month>
          <volume>29</volume>
          <issue>2</issue>
          <fpage>191</fpage>
          <lpage>199</lpage>
          <pub-id pub-id-type="doi">10.1080/09638237.2019.1677878</pub-id>
          <pub-id pub-id-type="medline">31694433</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref36">
        <label>36</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Valdez</surname>
              <given-names>D</given-names>
            </name>
            <name name-style="western">
              <surname>Ten Thij</surname>
              <given-names>M</given-names>
            </name>
            <name name-style="western">
              <surname>Bathina</surname>
              <given-names>K</given-names>
            </name>
            <name name-style="western">
              <surname>Rutter</surname>
              <given-names>LA</given-names>
            </name>
            <name name-style="western">
              <surname>Bollen</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Social media insights into US mental health during the COVID-19 pandemic: longitudinal analysis of Twitter data</article-title>
          <source>J Med Internet Res</source>
          <year>2020</year>
          <month>12</month>
          <day>14</day>
          <volume>22</volume>
          <issue>12</issue>
          <fpage>e21418</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.jmir.org/2020/12/e21418/"/>
          </comment>
          <pub-id pub-id-type="doi">10.2196/21418</pub-id>
          <pub-id pub-id-type="medline">33284783</pub-id>
          <pub-id pub-id-type="pii">v22i12e21418</pub-id>
          <pub-id pub-id-type="pmcid">PMC7744146</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref37">
        <label>37</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Massey</surname>
              <given-names>PM</given-names>
            </name>
            <name name-style="western">
              <surname>Leader</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Yom-Tov</surname>
              <given-names>E</given-names>
            </name>
            <name name-style="western">
              <surname>Budenz</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Fisher</surname>
              <given-names>K</given-names>
            </name>
            <name name-style="western">
              <surname>Klassen</surname>
              <given-names>AC</given-names>
            </name>
          </person-group>
          <article-title>Applying multiple data collection tools to quantify human papillomavirus vaccine communication on Twitter</article-title>
          <source>J Med Internet Res</source>
          <year>2016</year>
          <month>12</month>
          <day>05</day>
          <volume>18</volume>
          <issue>12</issue>
          <fpage>e318</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.jmir.org/2016/12/e318/"/>
          </comment>
          <pub-id pub-id-type="doi">10.2196/jmir.6670</pub-id>
          <pub-id pub-id-type="medline">27919863</pub-id>
          <pub-id pub-id-type="pii">v18i12e318</pub-id>
          <pub-id pub-id-type="pmcid">PMC5168526</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref38">
        <label>38</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Muric</surname>
              <given-names>G</given-names>
            </name>
            <name name-style="western">
              <surname>Wu</surname>
              <given-names>Y</given-names>
            </name>
            <name name-style="western">
              <surname>Ferrara</surname>
              <given-names>E</given-names>
            </name>
          </person-group>
          <article-title>COVID-19 vaccine hesitancy on social media: building a public Twitter data set of antivaccine content, vaccine misinformation, and conspiracies</article-title>
          <source>JMIR Public Health Surveill</source>
          <year>2021</year>
          <month>11</month>
          <day>17</day>
          <volume>7</volume>
          <issue>11</issue>
          <fpage>e30642</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://publichealth.jmir.org/2021/11/e30642/"/>
          </comment>
          <pub-id pub-id-type="doi">10.2196/30642</pub-id>
          <pub-id pub-id-type="medline">34653016</pub-id>
          <pub-id pub-id-type="pii">v7i11e30642</pub-id>
          <pub-id pub-id-type="pmcid">PMC8694238</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref39">
        <label>39</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Mackey</surname>
              <given-names>TK</given-names>
            </name>
            <name name-style="western">
              <surname>Purushothaman</surname>
              <given-names>V</given-names>
            </name>
            <name name-style="western">
              <surname>Haupt</surname>
              <given-names>M</given-names>
            </name>
            <name name-style="western">
              <surname>Nali</surname>
              <given-names>MC</given-names>
            </name>
            <name name-style="western">
              <surname>Li</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Application of unsupervised machine learning to identify and characterise hydroxychloroquine misinformation on Twitter</article-title>
          <source>The Lancet Digital Health</source>
          <year>2021</year>
          <month>02</month>
          <volume>3</volume>
          <issue>2</issue>
          <fpage>e72</fpage>
          <lpage>e75</lpage>
          <pub-id pub-id-type="doi">10.1016/s2589-7500(20)30318-6</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref40">
        <label>40</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Allem</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Escobedo</surname>
              <given-names>P</given-names>
            </name>
            <name name-style="western">
              <surname>Chu</surname>
              <given-names>K</given-names>
            </name>
            <name name-style="western">
              <surname>Soto</surname>
              <given-names>DW</given-names>
            </name>
            <name name-style="western">
              <surname>Cruz</surname>
              <given-names>TB</given-names>
            </name>
            <name name-style="western">
              <surname>Unger</surname>
              <given-names>JB</given-names>
            </name>
          </person-group>
          <article-title>Campaigns and counter campaigns: reactions on Twitter to e-cigarette education</article-title>
          <source>Tob Control</source>
          <year>2017</year>
          <month>03</month>
          <day>08</day>
          <volume>26</volume>
          <issue>2</issue>
          <fpage>226</fpage>
          <lpage>229</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/26956467"/>
          </comment>
          <pub-id pub-id-type="doi">10.1136/tobaccocontrol-2015-052757</pub-id>
          <pub-id pub-id-type="medline">26956467</pub-id>
          <pub-id pub-id-type="pii">tobaccocontrol-2015-052757</pub-id>
          <pub-id pub-id-type="pmcid">PMC5018457</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref41">
        <label>41</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Harris</surname>
              <given-names>JK</given-names>
            </name>
            <name name-style="western">
              <surname>Moreland-Russell</surname>
              <given-names>S</given-names>
            </name>
            <name name-style="western">
              <surname>Choucair</surname>
              <given-names>B</given-names>
            </name>
            <name name-style="western">
              <surname>Mansour</surname>
              <given-names>R</given-names>
            </name>
            <name name-style="western">
              <surname>Staub</surname>
              <given-names>M</given-names>
            </name>
            <name name-style="western">
              <surname>Simmons</surname>
              <given-names>K</given-names>
            </name>
          </person-group>
          <article-title>Tweeting for and against public health policy: response to the Chicago Department of Public Health's electronic cigarette Twitter campaign</article-title>
          <source>J Med Internet Res</source>
          <year>2014</year>
          <month>10</month>
          <day>16</day>
          <volume>16</volume>
          <issue>10</issue>
          <fpage>e238</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.jmir.org/2014/10/e238/"/>
          </comment>
          <pub-id pub-id-type="doi">10.2196/jmir.3622</pub-id>
          <pub-id pub-id-type="medline">25320863</pub-id>
          <pub-id pub-id-type="pii">v16i10e238</pub-id>
          <pub-id pub-id-type="pmcid">PMC4210950</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref42">
        <label>42</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Lazard</surname>
              <given-names>AJ</given-names>
            </name>
            <name name-style="western">
              <surname>Wilcox</surname>
              <given-names>GB</given-names>
            </name>
            <name name-style="western">
              <surname>Tuttle</surname>
              <given-names>HM</given-names>
            </name>
            <name name-style="western">
              <surname>Glowacki</surname>
              <given-names>EM</given-names>
            </name>
            <name name-style="western">
              <surname>Pikowski</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Public reactions to e-cigarette regulations on Twitter: a text mining analysis</article-title>
          <source>Tob Control</source>
          <year>2017</year>
          <month>12</month>
          <volume>26</volume>
          <issue>e2</issue>
          <fpage>e112</fpage>
          <lpage>e116</lpage>
          <pub-id pub-id-type="doi">10.1136/tobaccocontrol-2016-053295</pub-id>
          <pub-id pub-id-type="medline">28341768</pub-id>
          <pub-id pub-id-type="pii">tobaccocontrol-2016-053295</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref43">
        <label>43</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Merrill</surname>
              <given-names>JE</given-names>
            </name>
            <name name-style="western">
              <surname>Ward</surname>
              <given-names>RM</given-names>
            </name>
            <name name-style="western">
              <surname>Riordan</surname>
              <given-names>BC</given-names>
            </name>
          </person-group>
          <article-title>Posting post-blackout: a qualitative examination of the positive and negative valence of tweets posted after "blackout" drinking</article-title>
          <source>J Health Commun</source>
          <year>2020</year>
          <month>02</month>
          <day>01</day>
          <volume>25</volume>
          <issue>2</issue>
          <fpage>150</fpage>
          <lpage>158</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/31986999"/>
          </comment>
          <pub-id pub-id-type="doi">10.1080/10810730.2020.1719242</pub-id>
          <pub-id pub-id-type="medline">31986999</pub-id>
          <pub-id pub-id-type="pmcid">PMC7175394</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref44">
        <label>44</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Weitzman</surname>
              <given-names>ER</given-names>
            </name>
            <name name-style="western">
              <surname>Magane</surname>
              <given-names>KM</given-names>
            </name>
            <name name-style="western">
              <surname>Chen</surname>
              <given-names>P</given-names>
            </name>
            <name name-style="western">
              <surname>Amiri</surname>
              <given-names>H</given-names>
            </name>
            <name name-style="western">
              <surname>Naimi</surname>
              <given-names>TS</given-names>
            </name>
            <name name-style="western">
              <surname>Wisk</surname>
              <given-names>LE</given-names>
            </name>
          </person-group>
          <article-title>Online searching and social media to detect alcohol use risk at population scale</article-title>
          <source>Am J Prev Med</source>
          <year>2020</year>
          <month>01</month>
          <volume>58</volume>
          <issue>1</issue>
          <fpage>79</fpage>
          <lpage>88</lpage>
          <pub-id pub-id-type="doi">10.1016/j.amepre.2019.08.027</pub-id>
          <pub-id pub-id-type="medline">31806270</pub-id>
          <pub-id pub-id-type="pii">S0749-3797(19)30382-4</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref45">
        <label>45</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Krumm</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Horvitz</surname>
              <given-names>E</given-names>
            </name>
          </person-group>
          <article-title>Eyewitness: identifying local events via space-time signals in twitter feeds</article-title>
          <source>SIGSPATIAL '15: Proceedings of the 23rd SIGSPATIAL International Conference on Advances in Geographic Information Systems</source>
          <year>2015</year>
          <month>11</month>
          <day>03</day>
          <volume>20</volume>
          <fpage>1</fpage>
          <lpage>10</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://dl.acm.org/doi/10.1145/2820783.2820801"/>
          </comment>
          <pub-id pub-id-type="doi">10.1145/2820783.2820801</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref46">
        <label>46</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Qaiser</surname>
              <given-names>S</given-names>
            </name>
            <name name-style="western">
              <surname>Ali</surname>
              <given-names>R</given-names>
            </name>
          </person-group>
          <article-title>Text mining: use of TF-IDF to examine the relevance of words to documents</article-title>
          <source>IJCA</source>
          <year>2018</year>
          <month>07</month>
          <day>16</day>
          <volume>181</volume>
          <issue>1</issue>
          <fpage>25</fpage>
          <lpage>29</lpage>
          <pub-id pub-id-type="doi">10.5120/ijca2018917395</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref47">
        <label>47</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Wu</surname>
              <given-names>HC</given-names>
            </name>
            <name name-style="western">
              <surname>Luk</surname>
              <given-names>RWP</given-names>
            </name>
            <name name-style="western">
              <surname>Wong</surname>
              <given-names>KF</given-names>
            </name>
            <name name-style="western">
              <surname>Kwok</surname>
              <given-names>KL</given-names>
            </name>
          </person-group>
          <article-title>Interpreting TF-IDF term weights as making relevance decisions</article-title>
          <source>ACM Trans. Inf. Syst</source>
          <year>2008</year>
          <month>06</month>
          <day>01</day>
          <volume>26</volume>
          <issue>3</issue>
          <fpage>1</fpage>
          <lpage>37</lpage>
          <pub-id pub-id-type="doi">10.1145/1361684.1361686</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref48">
        <label>48</label>
        <nlm-citation citation-type="confproc">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Shi</surname>
              <given-names>N</given-names>
            </name>
            <name name-style="western">
              <surname>Liu</surname>
              <given-names>X</given-names>
            </name>
            <name name-style="western">
              <surname>Guan</surname>
              <given-names>Y</given-names>
            </name>
          </person-group>
          <article-title>Research on k-means Clustering Algorithm: An Improved k-means Clustering Algorithm</article-title>
          <year>2010</year>
          <conf-name>Third International Symposium on Intelligent Information Technology and Security Informatics</conf-name>
          <conf-date>April 2-4, 2010</conf-date>
          <conf-loc>Jian, China</conf-loc>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://ieeexplore.ieee.org/document/5453745"/>
          </comment>
          <pub-id pub-id-type="doi">10.1109/iitsi.2010.74</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref49">
        <label>49</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Drikvandi</surname>
              <given-names>R</given-names>
            </name>
            <name name-style="western">
              <surname>Lawal</surname>
              <given-names>O</given-names>
            </name>
          </person-group>
          <article-title>Sparse principal component analysis for natural language processing</article-title>
          <source>Ann. Data. Sci</source>
          <year>2020</year>
          <month>05</month>
          <day>18</day>
          <fpage>1</fpage>
          <pub-id pub-id-type="doi">10.1007/s40745-020-00277-x</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref50">
        <label>50</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Jolliffe</surname>
              <given-names>IT</given-names>
            </name>
            <name name-style="western">
              <surname>Cadima</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Principal component analysis: a review and recent developments</article-title>
          <source>Philos Trans A Math Phys Eng Sci</source>
          <year>2016</year>
          <month>04</month>
          <day>13</day>
          <volume>374</volume>
          <issue>2065</issue>
          <fpage>20150202</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/26953178"/>
          </comment>
          <pub-id pub-id-type="doi">10.1098/rsta.2015.0202</pub-id>
          <pub-id pub-id-type="medline">26953178</pub-id>
          <pub-id pub-id-type="pii">rsta.2015.0202</pub-id>
          <pub-id pub-id-type="pmcid">PMC4792409</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref51">
        <label>51</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Valdez</surname>
              <given-names>D</given-names>
            </name>
            <name name-style="western">
              <surname>Picket</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Young</surname>
              <given-names>B</given-names>
            </name>
            <name name-style="western">
              <surname>Golden</surname>
              <given-names>S</given-names>
            </name>
          </person-group>
          <article-title>On mining words: the utility of topic models in health education research and practice</article-title>
          <source>Health Promot Pract</source>
          <year>2021</year>
          <month>05</month>
          <volume>22</volume>
          <issue>3</issue>
          <fpage>309</fpage>
          <lpage>312</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://doi.org/10.1177/1524839921999050"/>
          </comment>
          <pub-id pub-id-type="doi">10.1177/1524839921999050</pub-id>
          <pub-id pub-id-type="medline">33759597</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref52">
        <label>52</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Valdez</surname>
              <given-names>D</given-names>
            </name>
            <name name-style="western">
              <surname>Pickett</surname>
              <given-names>AC</given-names>
            </name>
            <name name-style="western">
              <surname>Goodson</surname>
              <given-names>P</given-names>
            </name>
          </person-group>
          <article-title>Topic modeling: latent semantic analysis for the social sciences</article-title>
          <source>Social Science Quarterly</source>
          <year>2018</year>
          <month>09</month>
          <day>07</day>
          <volume>99</volume>
          <issue>5</issue>
          <fpage>1665</fpage>
          <lpage>1679</lpage>
          <pub-id pub-id-type="doi">10.1111/ssqu.12528</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref53">
        <label>53</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Bathina</surname>
              <given-names>KC</given-names>
            </name>
            <name name-style="western">
              <surname>Ten Thij</surname>
              <given-names>M</given-names>
            </name>
            <name name-style="western">
              <surname>Valdez</surname>
              <given-names>D</given-names>
            </name>
            <name name-style="western">
              <surname>Rutter</surname>
              <given-names>LA</given-names>
            </name>
            <name name-style="western">
              <surname>Bollen</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Declining well-being during the COVID-19 pandemic reveals US social inequities</article-title>
          <source>PLoS One</source>
          <year>2021</year>
          <month>7</month>
          <day>8</day>
          <volume>16</volume>
          <issue>7</issue>
          <fpage>e0254114</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://dx.plos.org/10.1371/journal.pone.0254114"/>
          </comment>
          <pub-id pub-id-type="doi">10.1371/journal.pone.0254114</pub-id>
          <pub-id pub-id-type="medline">34237087</pub-id>
          <pub-id pub-id-type="pii">PONE-D-21-07348</pub-id>
          <pub-id pub-id-type="pmcid">PMC8266050</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref54">
        <label>54</label>
        <nlm-citation citation-type="confproc">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Hutto</surname>
              <given-names>CJ</given-names>
            </name>
            <name name-style="western">
              <surname>Gilbert</surname>
              <given-names>E</given-names>
            </name>
          </person-group>
          <article-title>VADER: A Parsimonious Rule-Based Model for Sentiment Analysis of Social Media Text</article-title>
          <source>ICWSM</source>
          <year>2014</year>
          <month>05</month>
          <day>16</day>
          <conf-name>Eighth International AAAI Conference on Weblogs and Social Media</conf-name>
          <conf-date>June 1-4, 2014</conf-date>
          <conf-loc>Ann Arbor, MI</conf-loc>
          <fpage>216</fpage>
          <lpage>225</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://www.aaai.org/ocs/index.php/ICWSM/ICWSM14/paper/viewPaper/8109"/>
          </comment>
          <pub-id pub-id-type="doi">10.1609/icwsm.v8i1.14550</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref55">
        <label>55</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Yang</surname>
              <given-names>K</given-names>
            </name>
            <name name-style="western">
              <surname>Varol</surname>
              <given-names>O</given-names>
            </name>
            <name name-style="western">
              <surname>Hui</surname>
              <given-names>P</given-names>
            </name>
            <name name-style="western">
              <surname>Menczer</surname>
              <given-names>F</given-names>
            </name>
          </person-group>
          <article-title>Scalable and generalizable social bot detection through data selection</article-title>
          <source>AAAI</source>
          <year>2020</year>
          <month>04</month>
          <day>03</day>
          <volume>34</volume>
          <issue>01</issue>
          <fpage>1096</fpage>
          <lpage>1103</lpage>
          <pub-id pub-id-type="doi">10.1609/aaai.v34i01.5460</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref56">
        <label>56</label>
        <nlm-citation citation-type="confproc">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Luceri</surname>
              <given-names>L</given-names>
            </name>
            <name name-style="western">
              <surname>Badawy</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Deb</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Ferrara</surname>
              <given-names>E</given-names>
            </name>
          </person-group>
          <article-title>Red bots do it better: Comparative analysis of social bot partisan behavior</article-title>
          <year>2019</year>
          <conf-name>WWW '19: Companion Proceedings of The 2019 World Wide Web Conference</conf-name>
          <conf-date>May 13-17, 2019</conf-date>
          <conf-loc>San Francisco, CA</conf-loc>
          <pub-id pub-id-type="doi">10.1145/3308560.3316735</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref57">
        <label>57</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Yang</surname>
              <given-names>K</given-names>
            </name>
            <name name-style="western">
              <surname>Ferrara</surname>
              <given-names>E</given-names>
            </name>
            <name name-style="western">
              <surname>Menczer</surname>
              <given-names>F</given-names>
            </name>
          </person-group>
          <article-title>Botometer 101: social bot practicum for computational social scientists</article-title>
          <source>J Comput Soc Sci</source>
          <year>2022</year>
          <month>08</month>
          <day>20</day>
          <fpage>1</fpage>
          <lpage>18</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/36035522"/>
          </comment>
          <pub-id pub-id-type="doi">10.1007/s42001-022-00177-5</pub-id>
          <pub-id pub-id-type="medline">36035522</pub-id>
          <pub-id pub-id-type="pii">177</pub-id>
          <pub-id pub-id-type="pmcid">PMC9391657</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref58">
        <label>58</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Eickhoff</surname>
              <given-names>M</given-names>
            </name>
            <name name-style="western">
              <surname>Wieneke</surname>
              <given-names>R</given-names>
            </name>
          </person-group>
          <article-title>Understanding topic models in context: a mixed-methods approach to the meaningful analysis of large document collections</article-title>
          <source>Proceedings of the 51st Hawaii International Conference on System Sciences</source>
          <year>2018</year>
          <fpage>903</fpage>
          <lpage>912</lpage>
          <pub-id pub-id-type="doi">10.24251/hicss.2018.113</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref59">
        <label>59</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Russell</surname>
              <given-names>AM</given-names>
            </name>
            <name name-style="western">
              <surname>Davis</surname>
              <given-names>RE</given-names>
            </name>
            <name name-style="western">
              <surname>Ortega</surname>
              <given-names>JM</given-names>
            </name>
            <name name-style="western">
              <surname>Colditz</surname>
              <given-names>JB</given-names>
            </name>
            <name name-style="western">
              <surname>Primack</surname>
              <given-names>B</given-names>
            </name>
            <name name-style="western">
              <surname>Barry</surname>
              <given-names>AE</given-names>
            </name>
          </person-group>
          <article-title>#Alcohol: portrayals of alcohol in top videos on TikTok</article-title>
          <source>J. Stud. Alcohol Drugs</source>
          <year>2021</year>
          <month>09</month>
          <volume>82</volume>
          <issue>5</issue>
          <fpage>615</fpage>
          <lpage>622</lpage>
          <pub-id pub-id-type="doi">10.15288/jsad.2021.82.615</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref60">
        <label>60</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Nordeck</surname>
              <given-names>CD</given-names>
            </name>
            <name name-style="western">
              <surname>Riehm</surname>
              <given-names>KE</given-names>
            </name>
            <name name-style="western">
              <surname>Smail</surname>
              <given-names>EJ</given-names>
            </name>
            <name name-style="western">
              <surname>Holingue</surname>
              <given-names>C</given-names>
            </name>
            <name name-style="western">
              <surname>Kane</surname>
              <given-names>JC</given-names>
            </name>
            <name name-style="western">
              <surname>Johnson</surname>
              <given-names>RM</given-names>
            </name>
            <name name-style="western">
              <surname>Veldhuis</surname>
              <given-names>CB</given-names>
            </name>
            <name name-style="western">
              <surname>Kalb</surname>
              <given-names>LG</given-names>
            </name>
            <name name-style="western">
              <surname>Stuart</surname>
              <given-names>EA</given-names>
            </name>
            <name name-style="western">
              <surname>Kreuter</surname>
              <given-names>F</given-names>
            </name>
            <name name-style="western">
              <surname>Thrul</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Changes in drinking days among United States adults during the COVID-19 pandemic</article-title>
          <source>Addiction</source>
          <year>2022</year>
          <month>02</month>
          <day>12</day>
          <volume>117</volume>
          <issue>2</issue>
          <fpage>331</fpage>
          <lpage>340</lpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/34159674"/>
          </comment>
          <pub-id pub-id-type="doi">10.1111/add.15622</pub-id>
          <pub-id pub-id-type="medline">34159674</pub-id>
          <pub-id pub-id-type="pmcid">PMC8441933</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref61">
        <label>61</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Rodriguez</surname>
              <given-names>LM</given-names>
            </name>
            <name name-style="western">
              <surname>Litt</surname>
              <given-names>DM</given-names>
            </name>
            <name name-style="western">
              <surname>Stewart</surname>
              <given-names>SH</given-names>
            </name>
          </person-group>
          <article-title>Drinking to cope with the pandemic: The unique associations of COVID-19-related perceived threat and psychological distress to drinking behaviors in American men and women</article-title>
          <source>Addict Behav</source>
          <year>2020</year>
          <month>11</month>
          <volume>110</volume>
          <fpage>106532</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/32652385"/>
          </comment>
          <pub-id pub-id-type="doi">10.1016/j.addbeh.2020.106532</pub-id>
          <pub-id pub-id-type="medline">32652385</pub-id>
          <pub-id pub-id-type="pii">S0306-4603(20)30662-6</pub-id>
          <pub-id pub-id-type="pmcid">PMC7320671</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref62">
        <label>62</label>
        <nlm-citation citation-type="journal">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Bunting</surname>
              <given-names>AM</given-names>
            </name>
            <name name-style="western">
              <surname>Frank</surname>
              <given-names>D</given-names>
            </name>
            <name name-style="western">
              <surname>Arshonsky</surname>
              <given-names>J</given-names>
            </name>
            <name name-style="western">
              <surname>Bragg</surname>
              <given-names>MA</given-names>
            </name>
            <name name-style="western">
              <surname>Friedman</surname>
              <given-names>SR</given-names>
            </name>
            <name name-style="western">
              <surname>Krawczyk</surname>
              <given-names>N</given-names>
            </name>
          </person-group>
          <article-title>Socially-supportive norms and mutual aid of people who use opioids: An analysis of Reddit during the initial COVID-19 pandemic</article-title>
          <source>Drug Alcohol Depend</source>
          <year>2021</year>
          <month>05</month>
          <day>01</day>
          <volume>222</volume>
          <fpage>108672</fpage>
          <comment>
            <ext-link ext-link-type="uri" xlink:type="simple" xlink:href="https://europepmc.org/abstract/MED/33757708"/>
          </comment>
          <pub-id pub-id-type="doi">10.1016/j.drugalcdep.2021.108672</pub-id>
          <pub-id pub-id-type="medline">33757708</pub-id>
          <pub-id pub-id-type="pii">S0376-8716(21)00167-8</pub-id>
          <pub-id pub-id-type="pmcid">PMC8057693</pub-id>
        </nlm-citation>
      </ref>
      <ref id="ref63">
        <label>63</label>
        <nlm-citation citation-type="confproc">
          <person-group person-group-type="author">
            <name name-style="western">
              <surname>Deb</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Majmundar</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Seo</surname>
              <given-names>S</given-names>
            </name>
            <name name-style="western">
              <surname>Matsui</surname>
              <given-names>A</given-names>
            </name>
            <name name-style="western">
              <surname>Tandon</surname>
              <given-names>R</given-names>
            </name>
            <name name-style="western">
              <surname>Yan</surname>
              <given-names>S</given-names>
            </name>
            <name name-style="western">
              <surname>Allem</surname>
              <given-names>JP</given-names>
            </name>
            <name name-style="western">
              <surname>Ferrara</surname>
              <given-names>E</given-names>
            </name>
          </person-group>
          <article-title>Social bots for online public health interventions</article-title>
          <year>2018</year>
          <conf-name>IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining (ASONAM)</conf-name>
          <conf-date>August 28-31, 2018</conf-date>
          <conf-loc>Barcelona, Spain</conf-loc>
          <pub-id pub-id-type="doi">10.1109/ASONAM.2018.8508382</pub-id>
        </nlm-citation>
      </ref>
    </ref-list>
  </back>
</article>
