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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>International Workshop on Data Mining and Knowledge Engineering, October</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Stay Some More and Buy? Modeling the Effects of Visit Time on Online Shopping Purchases</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Valerii Sychov</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Maxim Bakaev</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Novosibirsk State Technical University</institution>
          ,
          <addr-line>Novosibirsk, 630073</addr-line>
          ,
          <country country="RU">Russia</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2020</year>
      </pub-date>
      <volume>1</volume>
      <fpage>5</fpage>
      <lpage>16</lpage>
      <abstract>
        <p>Research in online commerce is heavily focused on identifying and understanding the factors that drive behaviors of users, since such findings can have immediate and direct impact on the sales volumes. One of the long-established principles in the field have been that the more time a prospective customer spends in a visit, the more likely is the purchase decision. Meanwhile, the annual growth of mobile commerce (20-35%) is even higher than of ecommerce in general (15-20%), and many established beliefs about web users' behavior are shifting. In our paper we build two simple models with datasets available through Kaggle repository, to explore the effect of visit time on purchase decisions and online revenues. The results suggest that the time spent on mobile app did have moderate effect on the sales (R2 = 0.249), while time spent on website was not significant at all. The F1-score in the classification model for the visitors' buy / no buy decision was also rather low, at 0. Correspondingly, we discuss some other related factors that could be used to enhance the quality of the models and presumably improve the online sales. Thus our results might be of interest to both machine learning specialists and to electronic commerce or marketing practitioners.</p>
      </abstract>
      <kwd-group>
        <kwd>1 Machine learning</kwd>
        <kwd>e-commerce</kwd>
        <kwd>m-commerce</kwd>
        <kwd>user behavior</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        Every year the number of Internet users is increasing, which leads to an increase in the volume of
online purchases (e-commerce) by 15-20% annually [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], which far exceeds the growth of traditional
brick-and-mortar commerce. The reported main reasons for choosing shopping online are: low prices,
time savings and convenience [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. Correspondingly, a solid share of today’s -creosmeamrecrhce in e
seeks for the ways to increase online shopping revenue, particularly through better understanding of
online behavior of users.
      </p>
      <p>
        In conventional stores, it is generally very difficult to get information about the number of visitors,
the time spent in the store, where the customers come from, etc. On the contrary, modern web analytic
systems allow obtaining such information easily for e-shops. The main metric for online stores is the
number of sales, that is, user reaching the final product order or check-out page [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. To track this,
various systems for collecting statistics are utilized, such as Yandex.Metrica, Google Analytics and
some others.
      </p>
      <p>
        Visit duration has long been considered a key performance metric in e-commerce, enhancing
conversion rate and reflecting loyalty to the e-tailor. In a study from 2015 [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ], data from 94 online
stores underwent statistical analysis (in SPSS software) and several hypotheses were tested, with the
overall goal to measure financial return on website visit duration. The PLS (General Partial Least
Squares) simulations obtained did not show a relationship between website ranking and visit duration,
but in general a convincing model of user purchase decision-making has been devised. In an even
more established study [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ], the authors proposed a type II tobit model, which showed the visit
decisions to continue browsing or leave the website, as well as the length of time spent viewing each
of the pages. The results suggested that the propensity of visitors to continue browsing changed
dynamically, depending on the depth of the site visit, and the number of repeat visits. In [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ], the
authors investigated several groups of factors influencing the duration of a website visit. A random
effects model was employed to determine the influence of these factors on the visit duration and the
number of pages viewed by the user. The results suggested that older people and women spent more
time at websites, while the sites that featured lots of advertisements got lower visit times from most
studied user demographic groups.
      </p>
      <p>
        The results of the above and similar research works have been considered helpful in improving
(optimizing) e-commerce websites, to achieve longer average visit durations and presumably enhance
sales. As we mentioned above, the “time on site” metric has been important in online commerce
already two decades, the reasoning being as follows. The longer a user has spent in the online store,
the more interested she is in the products of this site [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ], and this interest should lead to a purchase.
But not only website browsing habits change; also in the past several years in has been repeatedly
noted that mobile commerce is growing even faster than e-commerce, with the reported annual
growth of 20-35% [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]. Mobile devices are already used in more than half visits to online stores, and
the sales are expected to catch up [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]. However, whether the factors affecting purchase-making
behavior of prospective online customers who use mobile applications are the same as for websites is
currently underexplored in research work that came to our attention.
      </p>
      <p>The research objective of our paper is investigating how the time spent by users in online stores
affects their income. For this end, we test two hypotheses:</p>
      <p>1. Does the time spent by the user on online store website affect the purchases (income from a
customer)?
2. Does the time spent by the user in m-commerce mobile application affect the income?</p>
      <p>In our study, we relied on two openly available datasets that we describe in the following Section.
In Section 3, we test the hypotheses using SPSS Statistics software2 and report the results. Finally, we
discuss the findings and make the conclusions.
2.
2.1.</p>
    </sec>
    <sec id="sec-2">
      <title>Method</title>
    </sec>
    <sec id="sec-3">
      <title>The Dataset Description</title>
      <p>
        The first dataset that we used was Online Shopper’s intentions, openly accessible through Kaggle
[
        <xref ref-type="bibr" rid="ref10">10</xref>
        ]. The dataset consists of 10 numeric and 8 categorical attributes for a total of 12,330 sessions.
They have been collected for a single website using Google Analytics. The times spent by users in
various webpages (administrative, informational, etc.) available in this dataset were independent
variables in our study. The dependent variable was the Revenue, which corresponds to the visitor’s
purchasing decision and have binary values (TRUE / FALSE). In Table 1 we show some records and
columns from the Online Shopper’s intentions as an example.
      </p>
      <p>
        The second dataset that we used in the study was the Linear Regression E-commerce Dataset, also
from the Kaggle repository [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ]. This dataset contains data about customers who buy clothes online,
in an e-shot that also offers advice on style and clothing. Customers come to the store, have sessions /
meetings with a personal stylist, and then they can go home and order the clothes of their choice
either through the mobile app or through the website. The dataset consists of eight attributes, making
up a total of 500 different customer data. Our independent variables were the time spent on the site
and the time spent in the mobile application. The dependent variable was the store’s annual income
(purchases) from the customer (note, that unlike in the first dataset, in the second the dependent
variable was rational scale). In Table 2 we present some extracts from the Linear Regression
Ecommerce Dataset as an example.
2 https://www.ibm.com/ru-ru/products/spss-statistics
      </p>
    </sec>
    <sec id="sec-4">
      <title>User Behavior Modeling</title>
      <p>
        User behavioral models are subdivided into short-term and long-term models. The construction of
the long-term models is mainly required for their further application (for example, for use in
recommender systems). Long-term behavior describes relatively stable user preferences based on an
extensive history. The short term models describe a user’s current activity and his / her actual
intentions. Each type of models has its own advantages and shortcomings – for instance, long-term
models can collapse when a web resource is updated, which happens rather often nowadays [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ].
      </p>
      <p>Since the datasets that we employ in our research involve relatively extensive user history, they
should correspond to long-term behavioral model. As a particular method we used for the analysis of
the two datasets, logistic and linear regressions were chosen, in accordance to the data structure,
particularly the binary dependent variable of the Online Shopper’s intentions dataset.</p>
      <p>
        Logistic regression is a form of multiple regression, whose general purpose is to analyze the
relationship between multiple independent variables (also called regressors or predictors) and a
dependent variable. Binary logistic regression is applied when the dependent variable is binary – i.e. it
can take only two values. The independent variables are generally interval or rational scale, which is
exactly our case for the duration times. Through the use of logistic regression, it is possible to
estimate the probability that an event will occur for a particular subject (sick / healthy, loan repayment
/ default, etc.) [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]. The quality of logistic regression models is characterized with parameters that
correspond to data classification tasks: Precision, Recall, Specificity, Sensitivity, etc. (more detailed
information can be found e.g. in [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ]). The F1-score was calculated using the traditional harmonic
mean formulation:
(1)
      </p>
      <p>Linear regression, which we naturally employed for the Linear Regression E-commerce Dataset,
is used in statistical analysis and machine learning to describe the effect that one or several
independent variables (factors, regressors) have on a dependent (explained) variable. All variables are
rational or interval scale, which both the time and the annual revenue conform to, and the effect is
expressed as a linear dependence function. The quality of linear regression model is an extensive
research topic, but we in our current study used the widely recognized R-squared and significance
metrics.</p>
    </sec>
    <sec id="sec-5">
      <title>3. Results</title>
    </sec>
    <sec id="sec-6">
      <title>3.1. The Online Shopper's Intention Dataset</title>
      <p>First, we analyzed the Online Shopper's intention dataset, in which three independent variables are
involved: 1) the time of working with the administrative part of the site, 2) the time of working with
the information part of the site, and 3) the time of working with the product pages. In the dataset,
12112 records (98.2%) turned out being valid. The dependent binary variable, the site's income, takes
the value TRUE or FALSE: whether the user made a purchase during this session or not. The
regression model was built using the stepwise Forward LR method.</p>
      <p>When a model was built, with a cut-off value of 0.5 (default) the percentage of cases correctly
classified into observed categories was 84.4. However, the classes in the dataset are unbalanced: only
1875 (15.5%) visitors had made a purchase (TRUE), while 10,237 (84.5%) did not (FALSE). So we
varied cut-off values (0.45, 0.4, 0.35, 0.3, 0.25, 0.2, etc.), obtaining the resulting Precision and Recall
as presented in Table 3. Notably, at the cut-off value level of 0.15, the Accuracy of our model began
to decline rapidly (by 11.6% compared to the cut-off value of 0.2). The lowest threshold of the cut-off
value adjustment that we performed was 0.12, as Precision had achieved 1 at this level, the Accuracy
however being already rather poor, at 15.5. The maximum F1-score value (0.342) was found for the
cut-off value of 0.14.</p>
      <p>In Fig. 1 we present the Precision-Recall curve for the model, corresponding to the considered
cutoff values. In Fig. 2 we also show the ROC-curve – although it’s more suited for the case of the
balanced classes, we decided to include it for the illustrative purposes. The area under the curve is
0.681.</p>
      <p>As the quality of the classification model is relatively low, we can conclude that our hypothesis
“the time spent by the user on the website of the online store affects the purchase (income)”
supported much. The three considered time values failed to considerably improve over the “null”
predictor that would just predict TRUE for 15.5% of the classified cases.
3.2.</p>
    </sec>
    <sec id="sec-7">
      <title>The Linear Regression E-commerce Dataset</title>
      <p>The next dataset that we analyzed was the Linear Regression E-commerce Dataset, for which we
used the pairwise linear regression method. The multiple regression method was inappropriate
because the independent variables are highly collinear with each other, as can be seen in Fig. 3. We
built the first model in which we used the Time on App as the independent variable (the time the user
spent in the application during the year), and the Yearly Amount Spent (the sum of the user's
purchases for the entire year) as the dependent variable.</p>
      <p>The results of the linear regression analyses for the two independent variables are presented in
Table 4. The R2 = 0.249 for the Time on App is not very high, but it is considerably higher than
R2 &lt; 0.01 for the Time on Website variable, which was also not statistically significant. In the
regression equation for Time on App, the constant was not statistically significant (p = 0.608), which
is in line with the conceptual reasoning that zero time spent in online store cannot result in any
revenue from such a user. Still, we employ the regression analysis that includes the constant, for the
sake of comparability. In Fig. 4 we show the linear regression plot for the Time on App model.</p>
    </sec>
    <sec id="sec-8">
      <title>4. Discussion and Conclusions</title>
      <p>The linear regression analysis results presented in Table 4 suggest that the Time on App variable
much better explains the dependent variable than the Time on Website. Hence, it can be assumed that
time spent on an app is more likely to result in a purchase than time spent on a website. So, the
hypothesis 1 (impact of time on websites) should be rejected, as the classification model in the dataset
1 was weak and Time on Website was not significant in the dataset 2. The hypothesis 2 (impact of
time on mobile apps) can be confirmed, as Time on App was significant in the dataset 2, even though
the R2 = 0.249 was low.</p>
      <p>The low share of variance explained by the time in the online store revenue suggests the effect of
other important factors. Among the factors related to online store visits, we can note the week day of
the visit, whether the visit is a repeated one, the user’s region, etc. These deserve further explor
to improve the models for the dataset 2. In turn, our classification model for dataset 1 (F1 = 0.342)
may foremost suffer from lack of consideration of repeated visits. That is, in one visiting session the
user could obtain all the necessary information for the purchase decision-making, while the actual
purchase can be made during the next, shorter visit.</p>
      <p>
        However, the general outcome of the study is consistent with some related research, e.g. in [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ]
the authors conducted a study comparing purchases on a website and in a mobile application. The
results of the data analysis showed that customers feel more comfortable using mobile applications for
online shopping than on the website, in terms of ease of search, ease of access and so on. This may
suggest an ongoing shift of customers’ purchases towa-rcdosmmmerce, whereas websites (browsed
on desktop machines) are visited for other purposes. In any case, we would like to highlight that the
time spent in online stores still is still an important indicator of their operation, even if an indirect one.
First, it positively contributes to maintaining the interest of users in the store, which can lead to
potential purchases [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ]. Second, the duration of a visit to a website is an important factor that should
be considered when placing advertisements, which will lead to additional profits [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ]. On the other
hand, it might be exactly the excessive web advertisements that reduce usability and aesthetical
impression of websites and push users towards using mobile apps. The consideration of these mixed
effects in the online store user behavior models are among our further research plans.
      </p>
      <p>We would also like to note that our study was very much limited in the number of online stores
that were affected. In both Online Shopper’s intentions and the Linear Regression E-commerce
datasets, the data for only one (though different) online store is presented. Correspondingly, a study of
much larger scale is necessary before generalizing our conclusions.</p>
    </sec>
    <sec id="sec-9">
      <title>Acknowledgment</title>
      <sec id="sec-9-1">
        <title>The reported study was supported by ASU-3_20.</title>
      </sec>
      <sec id="sec-9-2">
        <title>Novosibirsk State Technical University’s research -grant TP 117</title>
      </sec>
    </sec>
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