Selling a cheaper mousetrap: Wal-Mart's effect on retail prices

I quantify the price effect of a low-cost entrant on retail prices using a case-study approach. I consider the effect of Wal-Mart entry on average city-level prices of various consumer goods by exploiting variation in the timing of store entry. The analysis combines two unique data sets, one containing opening dates of all US Wal-Mart stores and the other containing average quarterly retail prices of several narrowly-defined commonly-purchased goods over the period 1982-2002. I focus on 10 specific items likely to be sold at Wal-Mart stores and analyze their price dynamics in 165 US cities before and after Wal-Mart entry. An instrumental-variables specification corrects for measurement error in Wal-Mart entry dates. I find robust price effects for several products, including shampoo, toothpaste, and laundry detergent; magnitudes vary by product and specification, but generally range from 1.5-3% in the short run to four times as much in the long run.