Digitization and pre-purchase information: The causal and welfare impacts of reviews and crowd ratings

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.