The study looked at how often prices change in grocery stores. They found that prices in supermarkets don't change very often, staying the same for over 9 weeks on average for sale prices and over 14 weeks for regular prices. The study also found that some factors, like the type of store and the category of product, can affect how often prices change. Overall, the research shows that grocery stores tend to keep their prices stable for longer periods, with some flexibility in sale prices to balance it out.