Generative AI and User-Generated Content: Evidence from Online Reviews

How has generative artificial intelligence affected the quality and quantity of user-generated content? Our analysis of restaurant reviews on Yelp.com and product reviews on Amazon.com shows that, contrary to prior lab evidence, use of generative AI in text generation is associated with significant declines in online content quality. These results are similar both in OLS and in two- period differences-in-differences estimation based on within-reviewer changes in AI use. We also find that use of generative AI is associated with increases in per-reviewer quantity of content, and document heterogeneity in the observed effect between expert and non-expert reviewers, with the strongest declines in quality associated with use by non-experts.