This paper estimates the price sensitivity of individuals' choice of whether to buy computers online versus in retail stores using a new data source on the computer purchases of more than 20,000 people. The paper first fits hedonic regressions for the retail price of computers in a local area...

Homogeneous-producer models attribute lower prices in denser markets solely to lower optimal markups. I argue here that when producers have different production costs, competition-driven selection on costs also reduces prices. This selection mechanism can be distinguished from the...