A great Mixergy interview[1] was with Herb Sorensen, author of "Inside the Mind of the Shopper"[2]. There were many fascinating revelations about the grocery business. For example, he went through the four revenue sources for grocery stores and profit on selling the goods was in fourth place, behind real estate, shelf fees, and something else I can't remember. He also explained that there is an optimum layout for a store, with counterclockwise flow.

[1] http://mixergy.com/interviews/brick-mortar-retailers-herb-so...

[2]http://www.herbsorensen.com/herbsorensenauthor.html