The study looked at prices and promotions in U.S. grocery stores. They found that prices vary a lot between stores, and promotions play a big role in this. The differences in prices and promotions are mostly due to the store chain and the local market, rather than the overall market. Stores in the same chain have similar prices and promotions because they cater to similar customer demands. This means that it's hard to tell the difference in prices and promotions between stores in the same chain. Retail managers might find it difficult to set different prices for different stores.