Quick detection of any significant changes in customer usage behavior is of great importance for providers of subscriptionbased services. Such changes often reveal creeping trends in customer attitude toward using proposed services and could provide useful information for retention programs if recognized at the right time. Service industries such as telecommunications or online content providers propose various services to their customers for a given time interval. Produced by a series of indicator variables each of which denotes a particular service, a binary vector can represent the usage pattern of each customer at a given time period. Time dependent non-homogeneous behavior of customers causes the purchase rate of various services to form an auto-correlated multivariate Bernoulli distribution whose monitoring over time requires employing rather complicated statistical methods. Assuming a well-segmented market, this paper proposes a suitable probability model of customer behavior that can justify the inter-correlations among services and also the autocorrelation between successive values of service usage over time. In this paper, logistic regression models have been employed to represent heterogeneity across different classes of customers. To account for time dependent usage behavior, it is assumed that transition of customers across different classes takes place according to a Markov chain model.
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