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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>An Empirical Assessment of Customer Lifetime Value Models within Data Mining</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Abdulkadir Hiziroglu</string-name>
          <email>kadir.hiziroglu@bakircay.edu.tr</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Merve Sisci</string-name>
          <email>sevkiyemerve.oge@dpu.edu.tr</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Halil Ibrahim Cebeci</string-name>
          <email>hcebeci@sakarya.edu.tr</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Omer Faruk Seymen</string-name>
          <email>ofseymen@sakarya.edu.tr</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Bakircay University</institution>
          ,
          <addr-line>The Campus, 35665, Izmir</addr-line>
          ,
          <country country="TR">Turkey</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Dumlupinar University</institution>
          ,
          <addr-line>The Central Campus, 43100, Kutahya</addr-line>
          <country country="TR">Turkey</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Sakarya University</institution>
          ,
          <addr-line>The Esentepe Campus, 54050, Sakarya</addr-line>
          ,
          <country country="TR">Turkey</country>
        </aff>
      </contrib-group>
      <fpage>33</fpage>
      <lpage>42</lpage>
      <abstract>
        <p>Customer lifetime value has been of significant importance to marketing researchers and practitioners in specifying the importance level of each customer. By means of segmentation which could be carried out using valuebased characteristics it is indeed possible to develop tailored strategies for customers. In fact, approaches like data mining can facilitate extraction of critical customer knowledge for enhanced decision making. Although the literature has several analytical lifetime value models, comparative assessment of the existing models especially within the context of data mining seems a missing component. The aim of this paper is to compare two different customer lifetime value models within data mining. The evaluation was carried out within the context of customer segmentation using a database of a company operating in retail sector. The results indicated that two models yield the same segmentation structure and no statistical differences detected on the select control variables. However, the remaining model produced rather different segmentation results than their peers and it was possible to identify the most lucrative model according to the statistical analyses that were carried out on the select control variables.</p>
      </abstract>
      <kwd-group>
        <kwd>Customer lifetime value</kwd>
        <kwd>Customer segmentation</kwd>
        <kwd>Lifetime value modelling</kwd>
        <kwd>Data mining</kwd>
        <kwd>Customer analytics</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        Customer lifetime value (CLV) modelling is an analytical component of customer
relationship management and has been widely utilized by a variety of companies
across different sectors including finance and insurance, retail and
telecommunications in order to identify the differences between the customers. It is a measurement
of a firm’s net cash flows generated by its customers within specified lifetime
duration
        <xref ref-type="bibr" rid="ref16">(Gupta &amp; Lehmann, 2003)</xref>
        . Calculating lifetime value of customers precisely can
help companies to position them and to differentiate the most appropriate services.
There have been several lifetime value models in the related literature and these
models can be classified into two groups: past customer behavior models and future-past
customer behavior models. There are mainly two differences between these models.
The first difference is based on the assumption that whether the customers who are
subject to assessments will be active or not in the future, while the second difference
stems from the inclusion of costs of customers into the models. PCV Model (past
customer value); RFM Model (recency, frequency, monetary); SOW Model (share of
wallet) can be included in the first category which calculate the lifetime values by
only using the past data of customers. As far as the second category of the models is
concerned, although they all take the future behavior of customers into consideration
        <xref ref-type="bibr" rid="ref24">(Kumar, 2005)</xref>
        , some analytical models
        <xref ref-type="bibr" rid="ref16 ref3 ref31">(Berger &amp; Nasr, 1998; Gelbrich &amp;
Wünschmann, 2007; Gupta &amp; Lehmann, 2003; Rust, Venkatesan &amp; Kumar, 2004)</xref>
        include acquisition cost when calculating lifetime values while some others
        <xref ref-type="bibr" rid="ref2">(Bauer,
Hammerschmid &amp; Braehler, 2003)</xref>
        do not so. The vast majority of the literature
focuses on the latter category of the models either in modelling or empirical form,
however, the current literature lacks of comparative research on evaluating those CLV
models, especially within the context of segmentation (Lemon and Mark, 2006).
      </p>
      <p>The aim of this paper is to make a comparison between two customer lifetime
value models from segmentation perspective within data mining. The rest of the paper is
organized as the followings. The empirical studies of the related literature are
provided in Section 2. Section 3 presents the research method followed. Empirical research
results, including calculation of lifetime values for each model and the segmentation
structures obtained by the comparative models, and their assessments were presented
in section 4. In the last section of the article, conclusions and recommendations from
both academic and practical points were provided.
2</p>
    </sec>
    <sec id="sec-2">
      <title>Literature Review</title>
      <p>
        When the current literature on customer lifetime value modelling is examined the
models can simply be classified into two groups: the models that take into account
past customer behavior and the models consider both past and future behaviors. Every
past costumer behavior group models have unique parameters which is directly
related to model’s characteristics. Among the models RFM is most widely used one and it
has been utilized in marketing areas for almost decades
        <xref ref-type="bibr" rid="ref15">(Gupta et al., 2006)</xref>
        . The
future-past customer behavior models share the same principle that for every customer
how long it will be active is determined then net present values of these customers are
calculated throughout the activation period. Based on this principle most of the
models use common variable/constant parameters such as retention rate, marketing cost,
cash flow ratio and reduction rate.
      </p>
      <p>
        Most of the studies on future-past customer behavior models use retention rate to
determine the activation period
        <xref ref-type="bibr" rid="ref16 ref2 ref3 ref4">(Blattberg &amp; Deighton, 1996; Berger &amp; Nasr, 1998;
Bauer et al., 2003; Gupta &amp; Lehmann, 2003)</xref>
        . However, some of the models use
different set of criteria such as loyalty
        <xref ref-type="bibr" rid="ref23">(Kim &amp; Cha, 2002)</xref>
        , number of purchase period
        <xref ref-type="bibr" rid="ref8">(Dwyer, 1997)</xref>
        , length of service (Gelbrich &amp; Wünschman, 2007), recent transaction
time / recency
        <xref ref-type="bibr" rid="ref5 ref9">(Chang &amp; Tsay, 2004; Fader , Hardie &amp; Berger, 2004)</xref>
        , frequency of
buying
        <xref ref-type="bibr" rid="ref5 ref9">(Chang &amp; Tsay, 2004; Fader et al., 2004; Rust et al., 2004; Ramakishnan,
2006)</xref>
        . Within the activation period, determination of the monetary values of all
customers is crucial. Therefore, almost every future-past customer behavior models
include a monetary-oriented variable. The most common variables in these models are;
marketing cost
        <xref ref-type="bibr" rid="ref3">(Berger &amp; Nasr, 1998; Venkatesan &amp; Kumar; 2004; Gelbrich &amp;
Wünschman, 2007; Kumar et al., 2008)</xref>
        , cash flow ratio
        <xref ref-type="bibr" rid="ref3 ref8">(Dwyer, 1997; Berger &amp;
Nasr, 1998)</xref>
        and reduction rate (Gelbrich &amp; Wünschman, 2007). Also, different
parameters and variables complement these monetary values like acquisition rate and
cost
        <xref ref-type="bibr" rid="ref17 ref4">(Blattberg &amp; Deighton, 1996; Gupta, Lehmann &amp; Stuart, 2004)</xref>
        , discount rate
        <xref ref-type="bibr" rid="ref4">(Blattberg &amp; Deighton, 1996)</xref>
        , purchase intention
        <xref ref-type="bibr" rid="ref23">(Kim &amp; Cha, 2002)</xref>
        , monetary value
        <xref ref-type="bibr" rid="ref5">(Chang &amp; Tsay, 2004)</xref>
        , expected revenue
        <xref ref-type="bibr" rid="ref29">(Malthouse &amp; Blattberg, 2005)</xref>
        , contributed
value
        <xref ref-type="bibr" rid="ref1">(Aeron, Bhaskar, Sundararajan, Kumar &amp; Moorthy, 2008)</xref>
        .
      </p>
      <p>
        It is possible to find empirical studies in the related literature that utilized one of
the past customer behavior models. Most of the empirical studies use RFM models or
its extensions. These studies use different datasets from different sectors such as retail
        <xref ref-type="bibr" rid="ref26 ref27">(Lin &amp; Shih, 2011)</xref>
        , Banking
        <xref ref-type="bibr" rid="ref19 ref20">(Khajvand &amp; Tarokh, 2011)</xref>
        , textile
        <xref ref-type="bibr" rid="ref14">(Golmah &amp;
Mirhashemi, 2012)</xref>
        , wholesale
        <xref ref-type="bibr" rid="ref7">(Chuang &amp; Shen, 2008)</xref>
        , healthcare
        <xref ref-type="bibr" rid="ref19 ref20">(Khajvand,
Zolfaghar, Ashoori &amp; Alizadeh, 2011)</xref>
        and charity organizations
        <xref ref-type="bibr" rid="ref18">(Jonker, Piersma &amp;
Van den Poel, 2004)</xref>
        . Some authors use well-known RFM extension called LRFM (or
RFML) which include one or more parameters related to relationship length (or
period of activity)
        <xref ref-type="bibr" rid="ref26 ref27 ref32 ref33">(Lin, Wei, Weng &amp; Wu, 2011; Wu, Lin &amp; Liu, 2014)</xref>
        . Considerable
amount of studies use different methods including generalized regression, logistic
regression, quantile regression, latent class regression, CART, Markov chain
modelling, neural network to create past customer behavior model (Haenlein, Kaplan &amp;
Beeser, 2007).
      </p>
      <p>
        Aforementioned future-past customer behavior models were used in different
empirical studies in the related literature too. Reinartz &amp; Kumar (2000) utilized Berger &amp;
Nasr (1998)’s model in retail sector. The same model or an own conceptual model
was also used in petroleum
        <xref ref-type="bibr" rid="ref13">(Gloy, Akridge &amp; Preckel, 1997)</xref>
        , retail
        <xref ref-type="bibr" rid="ref6">(Chen, Yang &amp;
Lin, 2009)</xref>
        , telecommunication (Hwang et al., 2004), banking
        <xref ref-type="bibr" rid="ref11">(Glady, Baesens &amp;
Croux, 2009)</xref>
        sectors and with internet company datasets
        <xref ref-type="bibr" rid="ref17">(Gupta et al., 2004)</xref>
        .
Additionally Kim Jun, Sung &amp; Hwang (2006), and Glady, Lemmens &amp; Croux (2015) used
Kim &amp; Kim (1999)’s basic structural model as well as Fader et al. (2004)’s and Fader,
Hardie &amp; Lee (2005)’s models. Wu &amp; Li (2011) performed a CLV calculation using
the models of Kim &amp; Cha (2002). Kumar et al. (2008) adapted three different CLV
models that belong to Reinartz &amp; Kumar (2000), Rust et al. (2004) and Venkatesan &amp;
Kumar (2004) to perform an empirical study in information technology sector.
      </p>
      <p>In recent years, customer analytics has attracted a great deal of attention from both
researchers and practitioners. Data mining can help companies to select the right
prospects on whom to focus, offer the right additional products to company’s existing
customers and identify good customers who may be about to leave. Data mining can
predict the profitability of prospects as they become active customers, how long they
will be active customers, and how likely they are to leave. In addition, data mining
can be used over a period of time to predict changes in details.</p>
      <p>
        The significance usage of data mining techniques provides advantages in the areas
of modeling CLV, including performing analysis based on CLV and evaluating the
optimal method for identifying customer lifetime value in many industries such as
retail, insurance, banking, telecommunication, financial services
        <xref ref-type="bibr" rid="ref19 ref20 ref22 ref26 ref27 ref6">(Kim et al., 2006;
Chen et al., 2009; Khajvand &amp; Tarokh, 2011; Lin et al., 2011; Golmah &amp;
Mirhashemi; 2012; Hu et al., 2013)</xref>
        . These techniques include decision tree,
clustering, logistic regression, artificial neural network, support vector machine, random
forests, survival analysis, association rule a priori and self-organizing maps. On one
hand, while modeling techniques provide capability of CLV estimation, companies
have competitive advantages in terms of making decisions due to the analysis
activities based on CLV via data mining.
      </p>
      <p>When the existing empirical studies are reviewed, there are many different models
which either use past or past-future information to calculate CLV values. However, it
is difficult to find a comparative study with regards to the evaluation of different
lifetime value models from practical benefits and academic point of view, especially
within the scope of data mining and segmentation. This paper contributes to the
current literature by providing the results of an empirical work conducted on two
different representative models, which are RFM and Gelbrich &amp; Wünschmann Model
(GWM), using a database in a comparison based on data mining methodology with a
special focus on segmentation.
3</p>
    </sec>
    <sec id="sec-3">
      <title>Methodology</title>
      <p>Some of the previous empirical lifetime value studies that used large-scale customer
data demonstrate the broad usage of data mining methodology for the lifetime
valuemodelling problem and the usefulness of such methodology. The aim of this study is
to compare two different customer lifetime value models within the context of
customer segmentation. Based on the classification provided in the previous section two
representative models from the groups of models were compared and an assessment
using some control variables were carried out within segmentation context. In order to
accomplish that the variables in the acquired databases were operationalized based on
some assumptions for each model and they were put them in place to perform the
analyses and the comparison.</p>
      <p>The dataset was procured from a supermarket retail chain in the UK that includes
four consecutive months of around 300,000 customers. A simple random sampling
methodology was employed and approximately 1% of the database was used as the
study sample. A sample of 3,017 was obtained for conducting the analyses.</p>
      <p>The dataset includes fields such as customer number, store ID, cashier ID, date of
transaction, time of transaction, transaction value, number of unique products bought,
total number of products bought and tender type. However, the data fields necessary
to conduct the analyses were obtained. The operationalization of these variables for
each model is provided in Table 1 and Table 2.</p>
      <p>To understand methodology of the proposed comparison, it is important to be clear
about the definitions of two models used in this study. By contrast to the other two
models, RFM model is based on the past customer purchase behavior and R, F, M
notations indicate Recency, Frequency and Monetary values, respectively.</p>
      <p>CLV=∑</p>
      <p>(Equation 1)</p>
    </sec>
    <sec id="sec-4">
      <title>Empirical Results</title>
      <sec id="sec-4-1">
        <title>Lifetime Value Assessment and Segmentation</title>
        <p>For the purposes of this essay, the procedure applied in this section contains some
specific steps. At the beginning, lifetime value assessments or calculations of all
customers were carried out and then the corresponding segments based on these values
were generated. Regarding RFM model, labelling process for all customers was
carried out using the operationalization given in Table 3 according to their R, F, and M
values that were calculated separately for each of them. To be more accurate, each
individual value for a customer was compared with the corresponding average value
of all customers. If R (F, M) value of a customer was higher than the average R (F,
M) values of all customers this particular customer was labelled as RH (FH, MH),
while the R (F, M) value lower than the average R (F, M) was labelled as RL (FL,
ML); where the second letters in the labels indicate the status of being high and low,
respectively. In this way, with the aim of developing customer segments, eight
different R-F-M combinations were generated. Subsequently, based on their R, F and M
status, these combinations were classified into four groups. Table 4 gives information
about four obtained segments and their descriptions together with number of
customers in each dataset and the corresponding R-F-M combinations.</p>
        <p>The other customer lifetime value model, GWM, lifetime value of each customer
was calculated using Equation 1 provided in Table 2. Following this, in accordance
with the corresponding calculated values, the consumers were sorted in a descending
order for each model. To achieve an equivalent comparison base, in RFM and GWM
models, the total numbers of segments were set equal to the segment structure
generated by RFM model. Therefore, the first 220 customers in the ranking were described
as “high value customers”, the followed 1357 of them as “moderate-to-high value
customers”, the next 1254 of them as “low-to-moderate value customers” and the
remaining 186 customers as “low value customers”.
4.2</p>
      </sec>
      <sec id="sec-4-2">
        <title>Results of the Comparison</title>
        <p>Separate Assessment of the Segmentation Results for Each Model. Four different
customer segments were obtained for two models. In order to ensure that the
segments generated for each model can be identified according to the corresponding
segmentation bases that were used during the segmentation process, ANOVA tests
were performed at 0.05 level of significance for each segmentation structure, and
results were obtained as given in Table 4. And it can be said that the average values of
these variables were statistically different from each other.</p>
      </sec>
      <sec id="sec-4-3">
        <title>Verification of the Differences between Segmentation Structures of Each Model.</title>
        <p>
          Ensuring that the segmentation structure of each model is different from the other, the
difference was set forth through calculating the similarity of the segmentation results.
Cohen’s Kappa index was used to measure the agreement between the segmentation
structures obtained. An index value converges to “0” indicates that the agreement
between segmentation results is low, while a value close to “1” designates high level
of agreement. However, any value between 0 and 1 can represent a certain level of
agreement with a degree of randomness
          <xref ref-type="bibr" rid="ref25">(Landis &amp; Koch, 1977)</xref>
          . The results of
calculations demonstrated that the similarity percentage GWM and RFM were found to be
34%, respectively. It can be clearly seen that the segments generated by RFM and the
segments obtained through GWM include different customers at a substantial amount.
In another word, there is an observable defined pattern in the results of GWM
compared to RFM model in terms of customers groupings. Therefore, it is possible to
distinguish or discern the segment structures of each model. Such differences would
provide a basis for further comparison of the models.
        </p>
        <p>Comparison of the Models from Segmentation Perspective. The main objective of
this research is to make a comparison of different lifetime value models at segment
level for the purpose of discovering which one is superior to the others. The
comparison was performed based on ‘average revenues’ of the segments using four control
variables, namely, value per visit (average monetary value per visit/shopping), unique
product variety per visit (number of unique products bought per visit/shopping),
quantity per visit (total number of products bought per visit/shopping), and unique product
variety per quantity (number of unique products bought over total number of
products). Table 5 provides that information for each individual customer segment of the
comparative models.</p>
        <p>Table 5 illustrate the results of calculations of average revenues of customer
segments for value per visit, for unique product variety per visit, for quantity per visit and
for unique product per quantity. By considering all segments, there are statistically
significant differences in the mean value, unique product variety and quantity per visit
between different segmentation structures generated by two different models.
However, for the case of unique product variety per quantity, the differences between models
calculated for segment 1 is not significant due to its P value, therefore there is
insufficient evidence to claim that some of the means may be different from each other. In
the other cases, all the differences between segments are meaningful.</p>
        <p>The evidence from these results suggest that there is a difference between the
models based on Segment 1 and Segment 2, that the average revenues pertaining to
valuable segment for GWM yields higher gain compared to the corresponding results
of RFM model. On the contrary, when looking at the difference at Segment 3 GWM’s
average revenues seem to be lower in comparison with the associated results of their
peers.</p>
        <p>General evaluations of differences lead us to the conclusion that the segmentation
structures established by GWM were found to be more effective compared to RFM
model, since the GWM seems to be more capable of enabling the assignment of the
most valuable customers into the same segment. This means that GWM has the ability
to facilitate performing attraction of lucrative customers in one group and classifying
the new customers in a lower value segment in a better way.
5</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>Conclusion</title>
      <p>Discovering differences between customers and specifying profitability of each
customer have been one of the most important challenges in marketing. Firms can utilize
CLV models in order to determine the characteristics of their customers. Moreover,
through the means of customer segmentation, which could be carried out based on
these value-based characteristics, organizations are able to develop appropriate
strategies for supporting their decision making processes in customer relationship
management context. This has become rather easy considering the availability of
organized customer data and the approaches like data mining that can facilitate extraction
of critical customer knowledge. Although the use of customer lifetime value for
segmenting customers or formulating strategies tailored to them can be found in related
literature, there has been a lack of comprehensive studies pertaining to analyzing
different models and figuring out which model is superior to the others within data
mining context. This study proposed a comparison to assess two different customer life
time value models within data mining and from segmentation perspective by using
value-related attributes as well as certain product-usage related control variables. In
this context, at first, different CLV models were reviewed and two models that need
the same set of variables were chosen for comparative assessment. One of these
models is a past customer behavior model (RFM model), while the other model is
futurepast behavior model, Gelbrich &amp; Wünschmann Model. Subsequently, the models
were evaluated using the same data set based on the segmentation structure that they
established. Comparisons were carried out based on ‘average revenues’ of the
segments using four control variables via independent sample t-Test analyses. The results
of the study demonstrated that GVM yielded better performance for all control
variables and the segmentations obtained via this model could be seen more effective
compared to RFM model.</p>
      <p>In conclusion, the usage of CLV models and data mining techniques together
gives a tremendous capability to the firms in recognizing high value customer groups.
From this standpoint, this study provides two benefits to the current body of the
literature as well as to the marketing practice. First, the article enhances academic
understanding of existing CLV models from a taxonomic perspective. Second, the usage
lifetime value and segmentation concepts within data mining context can provide a
grasp of practical implementation in customer analytics area. In fact, comparison of
the segmentation structures of two lifetime value models using four different control
variables can facilitate a better comprehension from an empirical practice point of
view. Nevertheless, a number of limitations of this study and areas for future research
could also be mentioned. One limitation is that only a specific database was used to
assess these models. It is far better that more analyses could have been performed on
different datasets for different types of sectors. In addition, another important point is
that only two customer lifetime value models were utilized for comparisons since
these models need the same set of variables. Other lifetime value models could have
also been taken into account should it is possible to find common features for
comparative assessment. Last but not least, some assumptions had to be kept in mind due
to lack of specific consumer-related data/information. Making these assumptions
more relaxed and building the research framework on obtaining data sets that could be
more consistent with real conditions may ensure more robust results for future
research.</p>
    </sec>
  </body>
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            <surname>Wu</surname>
            ,
            <given-names>S. I.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Li</surname>
            ,
            <given-names>P. C.</given-names>
          </string-name>
          :
          <article-title>The relationships between CRM, RQ, and CLV based on different hotel preferences</article-title>
          .
          <source>International Journal of Hospitality Management</source>
          ,
          <volume>30</volume>
          (
          <issue>2</issue>
          ),
          <fpage>262</fpage>
          -
          <lpage>271</lpage>
          (
          <year>2011</year>
          )
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>