Using a model of horizontal differentiation where a variety dimension is added to Hotelling's (1929) "linear city" duopoly model, I show that even when costs and demand are symmetric, price discrimination may be an equilibrium phenomenon. In the model each customer have a preferred variety and a...

I derive the polar representation of Fieller's estimation of confidence sets for ratios and construct a polar plot of the test statistics for all angles associated with the ratios. This procedure helps in visualizing and clarifying, but also systematizing, the features of the Fieller solution....