DP17840 The Economics of Advice
A consumer wants to buy one of three different products. An expert observes which of the three products is the best match for the consumer. Under linear prices a monopolistic expert may truthfully reveal, may partially reveal, and may not reveal at all her information. The outcome is inefficient; moreover, the consumer gets some of the surplus. With a two-part tariff the expert truthfully reveals her information. The outcome is efficient and the expert appropriates the entire surplus. If experts are competitive, they also truthfully reveal; here all the surplus goes to consumers.