An Empirical Study of Free Product Sampling and Rating Bias

Free product sampling has increasingly become a popular promotional strategy and served as a new mechanism of product review generation in e-commerce. We empirically analyze how a product's engagement in free product sampling affects the product's review rating, and we also examine important contingent factors of product pricing and product popularity. Using a rich data set from Taobao. com and multiple identification strategies and estimation methods, we find that engaging in free product sampling increases product rating by 1.1%. We argue that it is consumers' reciprocal behavior of giving higher ratings as a return to retailers' beneficial actions that causes rating bias. We further find that the bias would be larger with higher original price but smaller with larger price discount and higher product popularity. Our empirical findings provide important contributions to the literature on product sampling and word-of-mouth and offer critical managerial implications to online retailers, rating system designers, and consumers.