The Impact of Performance-Based Advertising on the Prices of Advertised Goods

Abstract

An important current trend in advertising is the replacement of traditional pay-per-exposure (aka pay-per-impression) pricing models with performance based mechanisms in which advertisers pay only for measurable actions by consumers. Such pay-per-action mechanisms are becoming the predominant method of selling advertising on the Internet. Well-known examples include pay-per-click, pay-per-call and pay-per-sale. This work highlights an important, and hitherto unrecognized, side-effect of pay-per-action advertising. I find that, if the prices of advertised goods are endogenously determined by advertisers to maximize profits net of advertising expenses, pay-per-action mechanisms induce firms to distort the prices of their goods (usually upwards) relative to the prices that would maximize profits in settings where advertising is sold under pay-per-exposure methods. Upward price distortions reduce consumer surplus and one or both of advertiser profits and publisher revenues, leading to a net reduction in social welfare. They persist in current quality-weighted pay-per-action schemes, such as the ones used by Google and Yahoo. In the latter settings they always reduce publisher revenues relative to pay-per-exposure methods. I propose enhancements to today’s quality-weighted pay-per-action schemes that resolve these problems and show that the steady state limit of my enhanced mechanisms has identical allocation and revenue properties to those of an optimal pay-per-exposure mechanism.

Keywords: online advertising, pay-per-action, keyword auctions, game theory

JEL Classification: M37, D44