Big-box stores, food prices & the CPI

Abstract from The Impact of Big-Box Stores on Retail Food Prices and the Consumer Price Index, by Ephraim Leibtag (Economic Research Report No. (ERR-33) 41 pp, December 2006)

This report focuses on retail food market dynamics and how they affect food price variation across store formats. The differences in prices across store formats are especially noteworthy when compared with standard measures of food price inflation over time. Over the past 20 years, annual food price changes, as measured by the CPI, have averaged just 3 percent per year, while food prices for similar products can vary by more than 10 percent across store formats at any one point in time. Since the current CPI for food does not fully take into account the lower price option of nontraditional retailers, a gap exists between price changes as measured using scanner data versus the CPI estimate, even for the relatively low food inflation period of 1998-2003. This study estimates that the CPI for dairy products overstates food price change by 0.5 to 2.5 percentage points per year for dairy, eggs, and butter/margarine.