Digitization and Pre-Purchase Information: The Causal and Welfare Impacts of Reviews and Crowd Ratings
研究比较了专业评论和亚马逊星级评分对图书销量的因果影响，发现星级评分对消费者剩余的正面效应是传统评论的十倍以上。
Digitization has led to many new creative products, straining the capacity of professional critics and consumers. Yet, the digitization of retailing has also delivered new crowd-based sources of pre-purchase information. We compare the relative impacts of professional critics and crowd-based Amazon star ratings on consumer welfare in book publishing. Using various fixed effects and discontinuity-based empirical strategies, we estimate their causal impacts on sales. We use these causal estimates to calibrate a structural demand model. The aggregate effect of star ratings on consumer surplus is, in our baseline estimates, more than ten times the effect of traditional review outlets.