When stores like Wal-Mart, Sam's Club, and Costco began their rapid expansion in the 1990s, supermarkets were thrown for a loop. The limited service, thinner assortments, and “everyday low pricing” of items in these “supercenters” — including foodstuffs — created enormous cost savings and increased credibility with consumers. What was a Safeway or a Stop & Shop to do in the face of such brutal competition?

A new paper from Stanford GSB looks at the strategic pricing decisions made by grocery firms during that period in response to the shock to their local market positions by the entry of Wal-Mart. The paper answers the age-old question in the supermarket industry: Is “everyday low pricing” (EDLP) better than promotional (PROMO) pricing that attempts to attract consumers through periodic sales on specific items? Investigators find that while EDLP has lower fixed costs, PROMO results in higher revenues — which is why it is the preferred marketing strategy of many stores.

The research is also the first to provide econometric evidence that repositioning firms’ marketing approaches can be quite costly. Switching from PROMO to EDLP is six times more expensive than migrating the other way around — which explains why supermarkets did not shift en masse to an “everyday low pricing” format as predicted when Wal-Mart entered the game.

From this article from Stanford's GSB. Ex-Apple exec Ron Johnson can attest to the switching costs of going from EDLP to PROMO pricing; it cost him his job at J. C. Penney.

I'm a Costco regular, but I'll buy groceries at Safeway or other grocery stores sometimes just because or geographic convenience and longer shopping hours. If you have proprietary products, that also allows you to sidestep, to some extent, the EDLP war of attrition.

For commodity products, however, the more retail moves online, the less tenable it is for stores to rely on the sheer convenience of physical store proximity to bypass the EDLP game. The paper above looked at the entry of Wal-Mart, but of course the modern day successor to Wal-Mart as an e-commerce gorilla is Amazon. If you are selling the same commodities as Amazon, it's a brutal game, especially as the eventual customer expectation will likely be same-day delivery AND every day low prices for most retail goods. In that scenario, the findings of the researchers above would not hold.