On deriving and validating comparative statics of a symmetric model of advertising competition

In this article, a market share attraction model is estimated using a data set of six manufacturers related to the ready-to-eat cereal industry in the US. For each year of the studied period, the market share of each firm is less than 50%, and these market shares are further apart from one another. In the reported application is is demonstrated, for the first time in the literature, that if model parameters change, all rivals in the industry should adjust their advertising spending in a manner consistent with the symmetric competitive structure for which all market shares are equal. Implications of this important finding are discussed.