Why is negative advertising such a prominent feature of competition in the political market? We propose an explanation that is based on the \fewness" of competitors in a political race. The typical election in the United States is a two-candidate race. In such duopoly contests, there is a simple...

In this paper we introduce a new approach to estimating differentiated product demand systems that allows for products with zero sales in the data. Zeroes in demand are a common problem in product differentiated markets, but fall outside the scope of existing demand estimation techniques. Our...