  Currently, many e-commerce websites issue online/electronic coupons as an
effective tool for promoting sales of various products and services. We focus
on the problem of optimally allocating coupons to customers subject to a budget
constraint on an e-commerce website. We apply a robust portfolio optimization
model based on customer segmentation to the coupon allocation problem. We also
validate the efficacy of our method through numerical experiments using actual
data from randomly distributed coupons. Main contributions of our research are
twofold. First, we handle six types of coupons, thereby making it extremely
difficult to accurately estimate the difference in the effects of various
coupons. Second, we demonstrate from detailed numerical results that the robust
optimization model achieved larger uplifts of sales than did the commonly-used
multiple-choice knapsack model and the conventional mean-variance optimization
model. Our results open up great potential for robust portfolio optimization as
an effective tool for practical coupon allocation.
