Should you sell Pepsi and Coke in the same aisle? : (effects of different types of manufacturers' advertising on volumes, retail margins, and retail profits)

I model manufacturers competing through a retailer. I model two types of advertising that each firm can engage in: advertising that increases product differentiation and advertising that increases (possibly perceived) value of the product. While the two types of advertising result in qualitatively similar comparative statics without a retailer in the model, I show that a retailer's presence leads to different qualitative effects. For example, the presence of a retailer leads to the products becoming more homogeneous in equilibrium when advertising is endogenous. I show both the comparative static effects of advertising and what occurs in equilibrium if advertising is endogenous