I present a model to assess the impact of demand-side factors on the concentration of sales within large product assortments. Consumers face a search problem within an assortment of horizontally differentiated products supplied by a monopolist. They may search for a product match by drawing...

Despite heated debate about the pros and cons of online physician ratings, very little systematic work examines the correlation between physicians’ online ratings and their actual medical performance. Using patients’ ratings of physicians at RateMDs.com and the Florida Hospital Discharge...

Websites increasingly allow advertisers to choose whether to bid for advertising on a per-impression or per-click basis. We present the first analysis of this new hybrid auction market. The conventional wisdom in this industry is that brand advertisers (e.g., Coca-Cola) will bid for impressions,...