An Empirical Study of Free Product Sampling and Rating Bias

Many electronic commerce platforms and retailers have increasingly adopted free product sampling to promote products and to attract product reviews. We conjecture that consumers who receive free samples may reciprocate by giving higher ratings as a return to retailers’ beneficial action, which causes rating biases. Specifically, we are interested in understanding how free sampling promotion of a product affects the product’s rating and the roles of important contingent factors, including product pricing (i.e., list price and price discount) and product popularity. Analyzing data collected from Taobao.com , we find that, on average, engaging in free product sampling increases product rating by 1.1%. Moreover, the bias would be larger with higher original price but smaller with larger price discount and higher product popularity. Our findings suggest that retailers could conduct free sampling promotions to improve their product ratings, but consumers should be cautious about the possible biases in ratings, and platform operators or rating system designers should offer solutions to correct the biases.