Diversity and demand externalities: How cheap information can reduce welfare

Goods and services vary along a number of dimensions independently. Customers can choose to acquire information on the quality of some dimensions and not others. Their choices affect firms’ incentives to invest in quality and so lead to indirect externalities in consumers’ choices. We illustrate these ideas in a simple model with a monopolist selling a product with two characteristics, investments in quality with stochastic realizations and heterogeneous consumers. A fall in the cost of acquiring information on the quality of one characteristic leads more consumers to verify that characteristic. Consequently, the firm may under-provide quality on the other. This may paradoxically reduce consumer surplus, profits and welfare. Our discussion concludes with a number of potential extensions and applications of the basic framework