Crowd-sourced recommender platforms organize social learning about products by recommending items based on information … study how market structure affects experimentation, social learning, and welfare. I present a model of competing platforms …

We study learning in perfect competition. A price-taking firm sells a good whose quality is unknown to some buyers. The … uninformed buyers use the price to infer information about quality. The presence of noise on the supply prevents perfect learning … learning process of the uninformed buyers …

interaction between social learning and price com- petition gives rise to a rich set of dynamics. We give a tight characterization … asymmetry between optimism (which speeds up learning) and pessimism (slows down learning) which leads inefficiencies to arise …