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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Exploiting Reviews to Guide Users' Selections</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Nevena Dragovic</string-name>
          <email>nevenadragovic@u.boisestate.edu</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Categories and Subject Descriptors</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Maria Soledad Pera</string-name>
          <email>solepera@boisestate.edu</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Department of Computer Science, Boise State University</institution>
          ,
          <addr-line>Boise, ID</addr-line>
          ,
          <country country="US">USA</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>H.3.3 [Information Storage and Retrieval]: Clustering, Information Filtering</institution>
          ,
          <addr-line>Retrieval Models, Selection Process.</addr-line>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2015</year>
      </pub-date>
      <abstract>
        <p>We introduce HRS, a recommender that exploits user reviews and identifies the features that are most likely appealing to users. HRS incorporates this knowledge into the recommendation process to generate a list of top-k recommendations, each of which is paired with an explanation that (i) showcases why a particular item was recommended and (ii) helps users decide which items, among the ones recommended, are best tailored towards their individual interests. Empirical studies conducted using the Amazon dataset demonstrate the correctness of the proposed methodology.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Recommendation Engine</kwd>
        <kwd>Explanations</kwd>
        <kwd>Ranking</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        Suggestions generated by existing recommenders are not always
personalized and diverse enough to expose users to a wide range
of items within their realm of interest, not just popular ones [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ].
This is due to the fact that a common alternative for generating
recommendations is to rely on existing community data.
Suggesting the same items to similar users within a community
can be very vague and impersonal [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. Newly-developed strategies
take advantage of different users’ generated data to better identify
user preferences in an attempt to further personalize
recommendations [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. Another challenge faced by recommenders
      </p>
      <p>
        In this paper, we present the initial research conducted to attempt
to solve the issues mentioned above. We created Honest
Recommendation System (HRS), a novel recommender system
that shows items in their real light. In developing HRS, we focus
our efforts in using collected information from users’ reviews to
generate personalized suggestions with their corresponding
explanations. By incorporating into the recommendation process
the feature preferences of an individual user (inferred from his
reviews), we can get to know the user better than by simply
considering his rating patterns. We strive for the development of a
recommender system a user trusts by providing information he is
interested in, no matter if it has a positive or negative connotation.
Our main contribution is the increased effectiveness and
satisfaction on a domain independent recommender. This is
accomplished by giving users information they care about, which
helps them make the best decision, in terms of selecting the most
adequate item among the recommended ones. Users' overall
satisfaction with a recommender is related to the perceived quality
of its recommendations and explanations [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. Consequently,
users’ confidence is also increased.
      </p>
    </sec>
    <sec id="sec-2">
      <title>2. OUR PROPOSED RECOMMENDER</title>
      <p>In this section we discuss HRS overall recommendation process.
(Parameters used by HRS were empirically determined. However,
details are omitted due to page constrains.)
Identify User’s Interest on Items. Consider a user U, who is a
member of a popular site, such as Yelp or Amazon, which
archives U’s reviews and rating history. Given that we aim to
provide U with information he values and needs to choose among
suggested items, we examine reviews written by U and identify
the set of features (i.e., traits) that U cares the most about. Since
we know features are mainly expressed as nouns, we perform
semantic analysis on reviews1 and consider the frequency of
occurrence of nouns U employs in his reviews. We rely on
WordNet-based similarity measures (using WS4J java library,
specifically WuPalmer algorithm) to find and cluster similar
1 Using Stanford CoreNLP http://nlp.stanford.edu/software/.
terms, as different nouns can be used to express similar meaning.
Each cluster would contain most frequent terms together with its
closest words among the ones U uses in reviews. We do this to
learn what items’ traits U most frequently mentions in his reviews
and use that knowledge to predict which candidate items would be
of U‘s interest. The top-2 most frequently-used term clusters are
treated as U’s preferred features. Note that each cluster is labeled
using the most representative2 cluster term.</p>
      <sec id="sec-2-1">
        <title>Generate Candidate Recommendations. We take advantage of</title>
        <p>
          U’s historical data (i.e. rated items) and employ the well-known
matrix factorization strategy [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] based on LensKit implementation
to generate a number of candidate suggestions for U.
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>Generate Top-k Recommendations. We examine archived</title>
        <p>reviews for each candidate item I and following the same process
defined for identifying features of interest to U, we identify the
top-2 features most-frequently mentioned in reviews pertaining to
I. Thereafter, we generate a ranking score for I, which shows the
degree to which U’s preferred feature are addressed in I’s reviews.
This score is computed by averaging the degree of similarity
(defined based on WordNet using the RitaWordnet library)
between all the words in the term clusters generated for U and I.
This score represents the level of U’s interest in I and is used for
ranking U’s candidate items, such that the top-k ranked candidate
items are selected as the items to be recommended to U.
Generate Explanations. We generate the corresponding
explanation for each recommended item I by showing why I is
likely appealing to U. We do so by extracting the descriptions
other users provided on U’s preferred features pertaining to I from
archived reviews. We identify sentences in reviews pertaining to I
that include terms exactly-matching (or highly-similar as
determined using WordNet) to each of the labels generated for
U’s clusters. In the explanation of each recommended item, HRS
includes 3 sentences for each label. In doing so, HRS provides U
with sufficient information about the recommendations without
overwhelming U with too much information to read related to the
recommended items. As previously stated, we do not emphasize
the sentiment of the features, since our intent is not to make U like
one option more than another, but save U’s time in identifying
information important for him.</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. EXPERIMENTAL RESULTS</title>
      <p>
        We conducted initial experiments using the Software3 domain in
the Amazon Review dataset [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ], which consists of 68,464 users,
11,234 items, and 95,084 reviews. We evaluated the performance
of HRS in terms of Normalized Discounted Cumulative Gain
(NDCG), which considers the correctness of the
recommendations and penalizes relevant recommendations
positioned lower in the ranking. We compared HRS with a
baseline, yet popular, algorithm: Matrix Factorization (SVD). As
shown in Table 1, HRS outperforms SVD. The significant NDCG
improvement demonstrates that, in general, recommendations
2 Using WordNet, we generate a list of synonyms for each cluster
term, such that the most frequent term among these synonym lists
is treated as the corresponding cluster label.
3 Note that we developed HRS to be a generic recommender so it
can be used on items on varied domains, beyond the Software
domain we considered only for initial assessment purposes.
provided by HRS are preferred over the ones provided by SVD,
which does not consider users’ feature preferences.
      </p>
      <sec id="sec-3-1">
        <title>Metrics</title>
        <p>0.704
0.748</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. CONCLUSION &amp; FUTURE WORK</title>
      <p>We developed a new recommendation system that takes advantage
of ratings and reviews, to create personalized suggestions. The
first version of HRS, which showcases the main idea and purpose
of the system, generated promising results, yet there are
opportunities to explore in the future that will enhance its
performance. Even though HRS did better than SVD, we plan to
provide deeper examination and comparisons with other baseline
and state-of-the-art recommendation strategies. We will also
analyze the effect of considering only candidate items with rating
scores above 3, which we anticipate will improve the overall
performance of HRS. We will also extend the performance
evaluation by conducting online user studies to further verify the
fact that HRS helps users in making appropriate choices among
provided suggestions. One of the limitations of the current design
of our recommender is that only nouns extracted from reviews are
treated as features which cause losing rich information from
adjectives and verbs. To address this issue, we will conduct more
in-depth analysis on part-of-speech and type dependencies on
sentences in reviews. We are aware that HRS, in its current state,
does not entirely solve the “cold start” problem. We will consider
adopting a hybrid recommendation strategy that considers general
item metadata, along with the popularity of items, in addition to
examining alternative ways to extract information from reviews
and further work towards eradicating the cold start problem.</p>
    </sec>
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