Advertising Competition Under Consumer Inertia

We construct a multistage game-theoretic model of advertising and price competition in a differentiated products duopoly, in which proportions of consumers exhibit latent inertia in favor of repeat purchase. Advertising simultaneously plays the dual role in reducing such inertia through awareness and enhancing perceived brand value (persuasion). We derive the advertising price cross-effects and provide a theoretical reconciliation of the longstanding debate in the marketing literature regarding the impact of advertising on price sensitivity. We characterize the nature of equilibria under symmetry and show that when a large proportion of consumers exhibit inertial tendencies, then a multiplicity of equilibria exists. Marketing implications and comparative statics are discussed. Numerical simulations for asymmetric firms are presented, wherein we show that advertising is not a useful competitive tool for small firms. However, advertising spending by the large firm provides a halo effect for the average prices in the category, which has a positive externality on the small firm's profits. In the absence of the small brand advertising, larger brand shares encourage firms to allocate higher expenditures on advertising to enhance the perceived value of their brand, which in turn shore up the average prices in the industry from which all firms benefit.