Uncertainty-reduction or reciprocity? Understanding the effects of a platform-initiated reviewer incentive program on regular review generation

To stimulate product reviews, many e-commerce platforms have launched reviewer incentive programs in \nwhich free product samples are provided to reviewers in exchange for their ratings of the samples. This \nstudy focuses on an unexplored aspect of reviewer incentive programs—the impact of participating in such \nprograms on reviewers’ ratings of products they purchased normally (i.e., regular ratings). We find that \nafter reviewers join the program and receive free product samples, their average regular rating increases by \n2.25% (i.e., 0.093 more stars on the five-star scale). Our follow-up analyses indicate that the observed \nregular-rating increase can be attributed to an uncertainty-reduction effect evoked by the free product \nsamples, as opposed to a reciprocity effect. We further delve into the underlying mechanism by analyzing \nthe reviewers’ regular ratings at a granular, product-category level. Consistent with our theorization of the \nuncertainty-reduction effect, our findings reveal that reviewers’ regular-rating increase is driven by \nimproved assessment and knowledge about products sharing common attributes with the sampled products, \nresulting in better post-purchase outcomes. Our results demonstrate that apart from motivating the feedback \nfor the sampled products, free product sampling can reduce reviewers’ product uncertainty and trigger \nevident change in their regular ratings for the purchased products.