A regression model of product differentiation

This note develops a model of product differentiation that can be estimated using standard regression techniques and applies it to a panel data set of new car sales. The model allows for complex substitution patterns according to an overlapping nest structure that makes cars closer substitutes if the share brand, body type, and/or quality level. A nest comprising all the car alternatives ensure that they are closer substitutes with each other than with the outside good. In addition, the model comprises fixed effects by car model, controlling for unobserved car quality.