<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Multi-lingual Author Profiling Using Stylistic Features</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Abdul Sittar</string-name>
          <email>abdulsittar72@gmail.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Iqra Ameer</string-name>
          <email>Iqraameer133@gmail.om</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>COMSATS University Islamabad, Lahore Campus</institution>
          ,
          <country country="PK">Pakistan</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Author profiling is the identification of an author's traits by examining the text written by an author. Author profiling has many useful applications in security, criminal, marketing, identification of false accounts on shared communication websites, etc. We submitted our system to the FIRE'18-MAPonSMS (Multi-lingual Author Profiling on SMS), a shared task to classify the attributes of an author like gender and age group from multilingual text specifically English +Roman Urdu. Roman Urdu is common language specifically in SMS messaging, Facebook posts/comments and chats blog of games etc. Our presented system is based on 29 different stylistic features. On the training dataset, we have achieved best Accuracy = 73.714, for gender while using all 14-language-independent features together and Accuracy = 58.571 for age group by using all 29 features together. We obtained Accuracy = 0.55 and 0.37 on testing data for both gender and age respectively.</p>
      </abstract>
      <kwd-group>
        <kwd>Author profiling</kwd>
        <kwd>Multi-lingual text</kwd>
        <kwd>Machine Learning</kwd>
        <kwd>Roman Urdu</kwd>
        <kwd>Stylistic</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        Author profiling (AP) is the task of determining the writer’s traits, like age, gender,
profession, personality types and mother language by analyzing the written document.
Due to the heap of information on social networks, it became essential to classify user’s
characteristics. This chore has diverse applications in forensics, security, and in
marketing fields [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. For example, by using forensics and terrorism applications, we can
decrease the search space for the suspicious writer. In marketing point of view, these
facts can be essential to predict and target specific customers and to form new strategies
according to consumer’s interest and preferences.
      </p>
      <p>
        Recent tendencies in the domain include Multi-lingual AP [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ], that is, the
Multilingual document: “occurrence of more than two languages in a text document" [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ].
Multi-lingual AP settings match the necessities of a real-life situation of security
applications when the produced text by the authors can belong to a mixture of different
languages from the texts under examination.
      </p>
      <p>Following the emerging field, the FIRE’2018 shared task on Age and Gender
identification in SMS based author profiles (MAPonSMS), provided the training and testing
corpora that were composed of multi-lingual (English +Roman Urdu) SMS based
documents.</p>
      <p>Since the provided training data was in multi-lingual, one of our primary objectives
was to determine how our proposed technique is performing in the multi-lingual text.
The author profiling is supervised document classification task. We carried out
different experiments, i.e. (i) using all 29 stylistic features, (ii) using all 14-language
independent stylistic features and (iii) using individual language independent stylistic
features.</p>
      <p>
        In recent period, deep-learning methods [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ], such as word, character,
document-embedding and word approaches [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ], have been used for this specific problem; still, linear
models perform well, as they seem to be more robust in picking up stylistic information
in the author’s writing. So, we applied frequently used linear machine-learning (ML)
approaches.
      </p>
      <p>The document is prepared as follows. Section 2 discusses related work has been done
in this domain. Section 3 details about our approach for the FIRE’2018 shared the task.
Results and their analysis in section 4. The final section is five which concludes the
paper.
2</p>
    </sec>
    <sec id="sec-2">
      <title>Related Work</title>
      <p>
        The International PAN Competitions made remarkable progress in author profiling,
especially for the gender and age identification tasks [
        <xref ref-type="bibr" rid="ref1 ref6 ref7 ref8 ref9">1, 6, 7, 8, 9</xref>
        ]. In PAN-2017, 22
teams participated, and traditional machine-learning algorithms were used by most of
them [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ], like Logistic Regression [
        <xref ref-type="bibr" rid="ref13 ref3">3, 13</xref>
        ] or SVM [
        <xref ref-type="bibr" rid="ref10 ref11 ref12">10, 11, 12</xref>
        ]. Some of them applied
deep-learning techniques, especially word and character embedding [
        <xref ref-type="bibr" rid="ref13 ref16 ref4">4, 13, 16</xref>
        ], which
are considering competing techniques, but still, results are not up to the mark for the
Author Profiling task.
      </p>
      <p>
        As researchers are attracted towards the multi-lingual settings, however, there is only
one research study found in the literature that considering the same genre author
profiling task for multi-lingual text. [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] worked on multi-lingual corpus based on Roman
Urdu and English Facebook posts and comments for same genre author profiling.
Content-based and stylistic features were explored in this study and 10-fold cross-validation
was used for evaluation. They have achieved Accuracy = 0.875 on multi-lingual corpus
by word uni-gram, char 3-gram, and char 8-gram content-based approach. By using the
word bigram content-based approach, they got 0.750 accuracy for the age group
classification task.
3
3.1
      </p>
    </sec>
    <sec id="sec-3">
      <title>Proposed Approach</title>
      <sec id="sec-3-1">
        <title>Stylistic Feature Set</title>
        <p>There are three comprehensive categories have been used for automatic
identification of an author’s traits: (1) content-based methods – that aim to detect characteristic
of a writer by using content of the text, (2) stylistic-based methods – which try to predict
a writer’s demographics traits by analyzing writing style of the writer, and (3)
topicbased methods – are applied to classify characteristics of an author by using debated
topics in the text.</p>
        <p>For the FIRE’18-MAPonSMS Author Profiling competition, our system1 is based
on different statistical features. As this year training data of FIRE’18-MAPonSMS is
based on the multi-lingual SMS messages, i.e. Roman Urdu and English. This
systematic investigation purposes to detect some language independent stylistic features,
which are likely to perform in multi-lingual text. List of language-independent as
follows: Avg. Word Length, Avg. Sentence Length, %age of Words with Six and More
Letters, %age of Words with Two and Three Letters, %age of Question Sentences,
%age of Semicolons, %age of Punctuations, %age of Comma, %age of Short
Sentences, %age of Long Sentences, %age of Capitals, %age of Colons, %age of Digits,
and %age of Full Stop. However, further are not language independent: Avg. Syllables
Per Word, %age of Pronouns, %age of Prepositions, %age of Coordinating
Conjunctions, %age of Articles, %age of Words with One Syllable, %age of Words with Three
Plus Syllables, %age of Adjectives, %age of Determiners, %age of Interjections, %age
of Modals, %age of Nouns, %age of Personal Pronouns, %age of Verbs, and %age of
Adverbs.</p>
        <p>We can observe that the list mentioned above of features purposes to catch different
stylistic facts from a multi-lingual written text, which can be useful to uncover the age
group and gender of an unknown author.
4</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Experimental Setup</title>
      <p>The focus of the FIRE’18-MAPonSMS shared task 2018 is on two author attributes
(1) age and (2) gender identification on the multi-lingual text. The organizers provided
us training dataset composed of multi-lingual (Roman Urdu and English) SMS text
messages. There are two classes for gender (male, female) and three classes for the age
group (15-19, 20-24 and 25-xx).
4.1</p>
      <sec id="sec-4-1">
        <title>FIRE’18-MAPonSMS Training and Test Dataset for Author Profiling</title>
        <p>In the training dataset, for the gender classification, we have 210 male while 140
female labeled text documents. On the other hand for age group classification 108 text
documents are in the 15-19 age group, 176 are in the 20-24 category, and 66 are in
25xx age group. However, 150 files were provided for the testing phase.
1 The implementation (source code) details of our approach is provided in a repository at
https://github.com/abdulsittar/Multilingual-Author-Profiling</p>
      </sec>
      <sec id="sec-4-2">
        <title>Evaluation Methodology</title>
        <p>Author profiling classification problem is handled as a supervised ML problem. For
detection of the age group, there are multi–groups problem and objective is to classify
the age amongst 3-groups: (1) 15-19, (2) 20–24 and (3) 25–xx. For the gender
categorization, there are binary-groups and objective is to differentiate between 2 groups: (1)
female as well as the (2) male.</p>
        <p>10–fold cross-validation was used in experiments to evaluate the performance of our
model. We conducted our experiments by using four different ML algorithms named
Naive Bayes, J48, Random Forest and Logistic Regression. Implementation of WEKA
was used for these algorithms. The scores produced using the stylistic features are
manipulated as input to above-stated ML algorithms.
4.3</p>
      </sec>
      <sec id="sec-4-3">
        <title>Evaluation Measure</title>
        <p>As suggested by the organizing team of the FIRE’18-MAPonSMS shared the task,
the performance of the submitted automatic system for the age and gender was
measured using accuracy. Accuracy is described as the proportion of the correctly classified
predictions   out of all the predictions   made.</p>
        <p>=  
 
5</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>Results and Analysis</title>
      <p>For all the tables shown in this results and analysis section, next mentioned
terminologies are used. The “Classifier” indicates the ML algorithm which we have applied
to generate the numeric scores (NB → Naive Bayes, RF → Random Forest, LR →
Logistic Regression). Best results are highlighted in bold typeface. We performed three
sets of experiments: (1) performance on all 29 features, (2) performance on all 14
language independent features (see section 3.1) and (3) performance on individual
language independent features (by using every single feature).Results on Training Dataset</p>
      <p>Table 1 shows the scores using all 29 stylistic features for both groups, i.e., age and
gender. Using all features together we obtained best results by using Random Forest,
Accuracy = 73.714 for the gender and 53.142 for the age group classification. Table 2
depicts the results for all 14-language independent stylistic features collectively. We
achieved the best results for gender (Accuracy = 72.000) using Random Forest
classifier and for the age (Accuracy = 58.571) by using Logistic Regression.</p>
      <sec id="sec-5-1">
        <title>Classifiers</title>
        <p>NB
RF
LR
J48</p>
      </sec>
      <sec id="sec-5-2">
        <title>Classifiers</title>
        <p>NB
RF
LR
J48</p>
        <p>Table 3 displays the results using 14-language independent stylistic features
individually (for every single feature). RF was performing better on both age and gender
identification; therefore we are only reporting the results on single language-independent
features by using RF.</p>
        <p>The best results are obtained when “%age of Punctuations” single stylistic feature is
used for gender (Accuracy = 64.857) and “%age of Long Sentences” for age (Accuracy
= 50.285). This indicates that in SMS multi-lingual messages, one of the gender prefers
Punctuations than the other, while one of the age groups prefers longer messages than
others.</p>
        <p>Overall concerning algorithms, for age group identification, the best scores are
obtained using two classification algorithms named as RF and LG. For gender estimation,
best sores are achieved by RF algorithm. This shows that the RF algorithm is suitable
if we give a collection of attributes as an input to the algorithm in the classification
problem.
5.1</p>
      </sec>
      <sec id="sec-5-3">
        <title>Results on Test Dataset</title>
        <p>We obtained Accuracy = 0.55 and 0.37 on testing data for both gender and age
respectively, which is below the baseline (baseline for gender = 0.60 and age = 0.51).
Joint estimation of our model for both age and gender is 0.23.
6</p>
      </sec>
    </sec>
    <sec id="sec-6">
      <title>Conclusion</title>
      <p>Correct profiling of an unknown author is getting a reputation for security point of
view, investigation of criminal activities and the market research opinion. In this paper,
we have participated in our approach in the FIRE'18-MAPonSMS author profiling
shared task on age and gender identification in multi-lingual text. We have shown how
the stylistic features and machine learning techniques enable an automatic system to
determine different characteristics of an unknown author efficiently.</p>
      <p>We have considered the stylistic features to uncover the traits of an author on the
multi-lingual corpus. We implemented 29 stylistic features and performed three
different set of experiments, i.e., compared the results by using all 29 features, analyzed the
scores for 14-language independent features altogether and at the end using single
language-independent features. We observed that best results are achieved when we used
all 29 features together for gender (Accuracy = 73.714) identification by Random
Forest and for the age (Accuracy = 58.571) group when used all 14-language independent
features by Logistic Regression classifier.</p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          1.
          <string-name>
            <surname>Rangel</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Rosso</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Potthast</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Stein</surname>
            ,
            <given-names>B.</given-names>
          </string-name>
          , and
          <string-name>
            <surname>Daelemans</surname>
            ,
            <given-names>W.</given-names>
          </string-name>
          (
          <year>2015</year>
          ).
          <article-title>Overview of the 3rd author profiling task at pan 2015</article-title>
          . In CLEF http://fire.irsi.res.in/fire/2018/home, last accessed
          <year>2018</year>
          /07/27.
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          2.
          <string-name>
            <given-names>Mehwish</given-names>
            <surname>Fatima</surname>
          </string-name>
          , Komal Hasan, Saba Anwar, Rao Muhammad Adeel Nawab (
          <year>2017</year>
          ),
          <article-title>"Multilingual author profiling on Facebook"</article-title>
          ,
          <source>Information Processing &amp; Management, Elsevier</source>
          , pp:
          <fpage>886</fpage>
          -
          <lpage>904</lpage>
          , Vol:
          <volume>53</volume>
          , Issue: 4, Standard:
          <fpage>0306</fpage>
          -
          <lpage>4573</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          3.
          <string-name>
            <surname>Meylaerts</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <year>2010</year>
          .
          <article-title>Multilingualism and translation</article-title>
          .
          <source>Handbook of translation studies 1</source>
          ,
          <volume>227</volume>
          {
          <fpage>230</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          4.
          <string-name>
            <given-names>Sebastian</given-names>
            <surname>Sierra</surname>
          </string-name>
          ,
          <article-title>Manuel Montes-y-</article-title>
          <string-name>
            <surname>Gómez</surname>
            ,
            <given-names>Thamar</given-names>
          </string-name>
          <string-name>
            <surname>Solorio</surname>
          </string-name>
          , and
          <string-name>
            <surname>Fabio</surname>
            <given-names>A.</given-names>
          </string-name>
          <string-name>
            <surname>González</surname>
          </string-name>
          .
          <year>2017</year>
          .
          <article-title>Convolutional Neural Networks for Author Profling</article-title>
          .
          <source>In Working Notes Papers of the CLEF 2017 Evaluation Labs (CEUR Workshop Proceedings)</source>
          , Vol.
          <year>1866</year>
          .
          <article-title>CLEF and CEURWS</article-title>
          .org, Dublin, Ireland.
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          5.
          <string-name>
            <given-names>Ilia</given-names>
            <surname>Markov</surname>
          </string-name>
          , Helena Gómez-Adorno,
          <article-title>Juan-Pablo Posadas-Durán, Grigori Sidorov</article-title>
          , and
          <string-name>
            <given-names>Alexander</given-names>
            <surname>Gelbukh</surname>
          </string-name>
          .
          <year>2017</year>
          .
          <article-title>Author Profiling with Doc2vec Neural Network Based Docment Embeddings</article-title>
          .
          <source>In Proceedings of the 15th Mexican International Conference on Artificial Intelligence, MICAI 2016</source>
          , Vol.
          <volume>10062</volume>
          .
          <string-name>
            <surname>Part</surname>
            <given-names>II</given-names>
          </string-name>
          , LNAI, Springer, Cancún, Mexico,
          <fpage>117</fpage>
          -
          <lpage>131</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          6.
          <string-name>
            <surname>Rangel</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Rosso</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          ,
          <year>2013</year>
          .
          <article-title>On the Identification of Emotions and Authors' Gender in Facebook Comments on the Basis of Their Writing Style</article-title>
          .
          <source>In: Proceedings of the First International Workshop on Emotion and Sentiment in Social and Expressive Media: Approaches and Perspectives from AI</source>
          (ESSEM
          <year>2013</year>
          ). Vol.
          <volume>1096</volume>
          . CEUR Workshop Proceedings, Turin, Italy, pp.
          <volume>34</volume>
          {
          <fpage>46</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          7.
          <string-name>
            <surname>Rangel</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Rosso</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Moshe</surname>
            <given-names>Koppel</given-names>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            ,
            <surname>Stamatatos</surname>
          </string-name>
          ,
          <string-name>
            <given-names>E.</given-names>
            ,
            <surname>Inches</surname>
          </string-name>
          ,
          <string-name>
            <surname>G.</surname>
          </string-name>
          ,
          <year>2013</year>
          .
          <article-title>Overview of the Author Profiling Task at PAN 2013</article-title>
          .
          <article-title>In: CLEF 2013 Evaluation Labs</article-title>
          and Workshop Working Notes Papers. Valencia, Spain.
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          8.
          <string-name>
            <surname>Rangel</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Rosso</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Potthast</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Stein</surname>
            ,
            <given-names>B.</given-names>
          </string-name>
          ,
          <year>2017</year>
          .
          <article-title>Overview of the 5th Author Profiling Task at PAN 2017: Gender and Language Variety Identification in Twitter</article-title>
          .
          <source>In: Working Notes Papers of the CLEF 2017 Evaluation Labs. CEUR Workshop Proceedings. CLEF and CEUR-WS.org.</source>
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          9.
          <string-name>
            <surname>Rangel</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Rosso</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Verhoeven</surname>
            ,
            <given-names>B.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Daelemans</surname>
            ,
            <given-names>W.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Potthast</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Stein</surname>
            ,
            <given-names>B.</given-names>
          </string-name>
          ,
          <year>2016</year>
          .
          <article-title>Overview of the 4th author profiling task at PAN 2016: cross-genre evaluations</article-title>
          . In: Working Notes of CLEF 2016 -
          <article-title>Conference and Labs of the Evaluation forum</article-title>
          .
          <source>CEUR-WS.org, vora - Portugal</source>
          , pp.
          <volume>750</volume>
          {
          <fpage>784</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          10.
          <string-name>
            <surname>A. Pastor</surname>
          </string-name>
          Lopez-Monroy,
          <article-title>Manuel Montes-y-Go ´ mez, Hugo Jair-Escalante, Luis ´ Villasenõr Pineda, and</article-title>
          <string-name>
            <given-names>Thamar</given-names>
            <surname>Solorio</surname>
          </string-name>
          .
          <year>2017</year>
          .
          <article-title>Social-Media Users can be Profled by their Similarity with other Users</article-title>
          .
          <source>In Working Notes Papers of the CLEF 2017 Evaluation Labs (CEUR Workshop Proceedings)</source>
          , Vol.
          <year>1866</year>
          .
          <article-title>CLEF and CEUR-WS</article-title>
          .org, Dublin, Ireland.
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          11.
          <string-name>
            <surname>Ilia</surname>
            <given-names>Markov</given-names>
          </string-name>
          , Helena Gómez-Adorno, and
          <string-name>
            <given-names>Grigori</given-names>
            <surname>Sidorov</surname>
          </string-name>
          .
          <year>2017</year>
          .
          <article-title>Language-</article-title>
          and
          <string-name>
            <surname>Subtask-Dependent Feature</surname>
          </string-name>
          Selection and
          <article-title>Classifer Parameter Tuning for Author Profling</article-title>
          .
          <source>In Working Notes Papers of the CLEF 2017 Evaluation Labs (CEUR Workshop Proceedings)</source>
          , Vol.
          <year>1866</year>
          .
          <article-title>CLEF and CEUR-WS</article-title>
          .org, Dublin, Ireland.
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          12.
          <string-name>
            <surname>Eric</surname>
            <given-names>S.</given-names>
          </string-name>
          <string-name>
            <surname>Tellez</surname>
            , Sabino Miranda-Jiménez,
            <given-names>Mario</given-names>
          </string-name>
          <string-name>
            <surname>Graff</surname>
            , and
            <given-names>Daniela</given-names>
          </string-name>
          <string-name>
            <surname>Moctezuma</surname>
          </string-name>
          .
          <year>2017</year>
          .
          <article-title>Gender and Language-Variety Identifcation with microTC</article-title>
          .
          <source>In Working Notes Papers of the CLEF 2017 Evaluation Labs (CEUR Workshop Proceedings)</source>
          , Vol.
          <year>1866</year>
          .
          <article-title>CLEF and CEUR-WS</article-title>
          .org, Dublin, Ireland.
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          13.
          <string-name>
            <surname>Andrey</surname>
            <given-names>Ignatov</given-names>
          </string-name>
          , Liliya Akhtyamova,
          <string-name>
            <given-names>and John</given-names>
            <surname>Cardiff</surname>
          </string-name>
          .
          <year>2017</year>
          .
          <article-title>Twitter Author Profling Using Word Embeddings and Logistic Regression</article-title>
          .
          <source>In Working Notes Papers of the CLEF 2017 Evaluation Labs (CEUR Workshop Proceedings)</source>
          , Vol.
          <year>1866</year>
          .
          <article-title>CLEF and CEUR-WS</article-title>
          .org, Dublin, Ireland.
        </mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>
          14.
          <string-name>
            <surname>Matej</surname>
            <given-names>Martinc</given-names>
          </string-name>
          , Iza Škrjanec, Katja Zupan, and
          <string-name>
            <given-names>Senja</given-names>
            <surname>Pollak</surname>
          </string-name>
          .
          <year>2017</year>
          .
          <article-title>PAN 2017: Author Profling - Gender and Language Variety Prediction</article-title>
          .
          <source>In Working Notes Papers of the CLEF 2017 Evaluation Labs (CEUR Workshop Proceedings)</source>
          , Vol.
          <year>1866</year>
          .
          <article-title>CLEF and CEUR-WS</article-title>
          .org, Dublin, Ireland.
        </mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          15.
          <string-name>
            <surname>Marc</surname>
            Franco-Salvador, Nataliia Plotnikova, Neha Pawar, and
            <given-names>Yassine</given-names>
          </string-name>
          <string-name>
            <surname>Benajiba</surname>
          </string-name>
          .
          <year>2017</year>
          .
          <article-title>Subword-based Deep Averaging Networks for Author Profling in Social Media</article-title>
          .
          <source>In Working Notes Papers of the CLEF 2017 Evaluation Labs (CEUR Workshop Proceedings)</source>
          , Vol.
          <year>1866</year>
          .
          <article-title>CLEF and CEUR-WS</article-title>
          .org, Dublin, Ireland.
        </mixed-citation>
      </ref>
      <ref id="ref16">
        <mixed-citation>
          16.
          <string-name>
            <surname>Sebastian</surname>
            <given-names>Sierra</given-names>
          </string-name>
          ,
          <article-title>Manuel Montes-y-</article-title>
          <string-name>
            <surname>Gómez</surname>
            ,
            <given-names>Thamar</given-names>
          </string-name>
          <string-name>
            <surname>Solorio</surname>
          </string-name>
          , and
          <string-name>
            <surname>Fabio</surname>
            <given-names>A.</given-names>
          </string-name>
          <string-name>
            <surname>González</surname>
          </string-name>
          .
          <year>2017</year>
          .
          <article-title>Convolutional Neural Networks for Author Profling</article-title>
          .
          <source>In Working Notes Papers of the CLEF 2017 Evaluation Labs (CEUR Workshop Proceedings)</source>
          , Vol.
          <year>1866</year>
          .
          <article-title>CLEF and CEUR-WS</article-title>
          .org, Dublin, Ireland.
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>