Charles Courtemanche and I have been working on a series of papers about Big-Box Retail (Walmart, specifically), and the new version of our Big Boxes-and-Obesity paper should be available and back under review soon. Forbes asked me to write an article about this paper; it's in the June 8 issue and on their website (no link because my Mac hates Movable Type).

One thing that is emerging in the new version of the paper is that warehouse clubs matter a lot. We think this is true for two reasons. The first is the income effect: lower prices equal higher real incomes, so we can buy better stuff. The second is warehouse clubs represent a different shopping technology: you get mostly brand names, largely in bulk. This allows people to constrain their future choices by stocking up on healthy foods now. My present self might anticipate loss aversion by my future self. Knowing this, my present self buys a load of healthy stuff that my future self won't want to see go to waste.

I got to experience both this afternoon. First, we bought a bunch of fresh vegetables at the Memphis Farmers' Market--presumably, we were able to afford this because on our last visit to Sam's Club, we were advised that we've saved $214 this year by shopping there (mostly on diapers and formula). Second, while I was at Sam's Club this afternoon, my wife called to see if I could find something for dinner. I thought "maybe we should just go out," but then I realized that I would probably order a burger & fries or something else I shouldn't be eating. I decided instead to find something healthier to prepare at home. Then it dawned on me that this is exactly one of the mechanisms by which we think warehouse clubs are reducing weight.

It's only a single data point and proof-by-introspection probably isn't going to fly at most journals, but at the very least it suggests to me that our story about the mechanism is plausible. I spent last Friday with Charles at UNC-Greensboro--a nice campus and a nice town, incidentally--working on this paper and another that will estimate the impact of Costco, Sam's Club, and BJ's Wholesale Club on grocery prices. We're adding more data, and both will be available by the end of the summer at the latest.