Commonly used discrete-choice models such as logit, nested logit, and random-coefficients models place very strong restrictions on how unobservable characteristic space changes with the number of products. We argue (and show with Monte Carlo experiments)that these restrictions can lead to biased...

We examine the effect of competition on second-degree price discrimination in display advertising in Yellow Pages directories. Our main empirical finding is that while competition is associated with lower prices, the association is not proportional along the range of product offerings. Instead,...