The correlation between supermarket size and national obesity prevalence

BACKGROUND: Supermarkets provide healthy and affordable food options while simultaneously heavily promoting energy-dense, nutrient-poor foods and drinks. Store size may impact body weight via multiple mechanisms. Large stores encourage purchasing of more food in a single visit, and in larger packages. In addition they provide greater product choice (usually at lower prices) and allow greater exposure to foods of all types. These characteristics may promote purchasing and consumption. Our objective was to assess the relationship between supermarket size and obesity, which has rarely been assessed. RESULTS: Data on supermarket size (measured as total aisle length in metres) was from 170 stores in eight developed countries with Western-style diets. Data for national obesity prevalence was obtained from the UK National Obesity Observatory. We found a strong correlation between average store size and national obesity prevalence (r = 0.96). CONCLUSIONS: Explanations for the association between store size and national obesity prevalence may include larger and less frequent shopping trips and greater choice and exposure to foods in countries with larger stores. Large supermarkets may represent a food system that focuses on quantity ahead of quality and therefore may be an important and novel environmental indicator of a pattern of behaviour that encourages obesity.

Directed search, coordination failure, and seller profits: an experimental comparison of posted pricing with single and multiple prices

We experimentally examine posted pricing and directed search. In one treatment, capacity-constrained sellers post fixed prices, which buyers observe before choosing whom to visit. In the other, firms post both “single-buyer” (applied when one buyer visits) and “multibuyer” (when multiple buyers visit) prices. We find, based on a 2 × 2 (two buyers and two sellers) market and a follow-up experiment with 3 and 2 × 3 markets, that multibuyer prices can be lower than single-buyer prices or prices in the one-price treatment. Also, allowing the multibuyer price does not affect seller profits and increases market frictions.