The server I’m working on does not allow me to install -dataex-, so I apologize for the lack of standardized example!

I’m working with a panel. I have individual-level purchase data from a chain of stores, and each person’s purchases were aggregated monthly. I have an id variable for each person (mvp_id) and an indicator variable for month (mthyr). I also have a variable that gives me the store ID where the person spent most money in each month (topstore1). I need to know how many people have (two or more) different top stores across the months in my dataset, versus how many people have the same top store across all months in my dataset.