I am working on a research project that has many subjects and program attendance data across multiple sheets. There are several programs and they each last many weeks. We want to know how many times they attended a session, but there are too many to go through and count individually. Is there a way that I can link the data for that person to their ID number to calculate the total sessions attended? The issue that I am running into with this, is that I am not able to link up the data across multiple excel sheets.

Thanks for your help.