Cross-buying is defined as the total number of different product categories that a customer has purchased from the firm from the time of his/her first purchase. Current business trends and past academic research clearly demonstrate the importance of cross-selling -- specific marketing effort by the firm to increase cross-buying -- in a non-contractual setting such as in retailing context. However, critical questions that warrant answers based on empirical evidence include: (1) what is the motivation for a customer to cross-buy? In other words, why do customers cross-buy from the same firm? (2) what product category needs to be promoted? (3) when is the best time to cross-promote a product category? and (4) how much should we cross-sell? Or, what is the optimal level of cross-promotion? The two essays proposed below address these questions and present answers based on empirical evidence. The purpose of the first essay titled “Why Cross-buy?” is to understand the motivation of customers to cross-buy and to identify the key drivers of cross-buy -- exchange characteristics, customer characteristics, product characteristics, and the firm’s marketing efforts. Further, we intend to empirically validate the positive impact of cross-buy on customer-based outcome metrics such as revenue/contribution margin per order, and the number of orders in a given period.

In the second essay titled “What, when, and how much to cross-sell? Optimizing Multi-category Catalog Mailing,” we answer the remaining questions- what, when and how much to cross-buy. We address an existing research gap -- lack of models to optimize multi-category mailing -- by introducing a competing risk hazard model employed in a Hierarchical Bayesian framework, to jointly estimate purchase timings and order amounts in multiple product categories. The proposed model integrates when and what components of a customer’s purchase decision into how much component of a firm’s cross-selling strategy using Dynamic Programming.

The results of the proposed essays have several implications for both practitioners and academics. While a key managerial implication is to use cross selling as a strategic tool to maximize CLV, the academic contributions relate to applying a competing risk hazard model and a Mutivariate Additive Risk Model to multi-category catalog retailing.