we compare retail stores from the current year with the last year. And the "like for like" KPI says that you can only compare stores from the current year with the same stores from the last year. So every new store in the current year must be ignored.
My Like for Like definition says that the store must have turnover in the same period in the last year. That means if I have 7. September 2009 which is a monday I have to check the 8. September in 2008 if there are also turnovers.
My concept is to load the previous year and than the actual year and than set a flag during the load proccess in the actual year if there is turnover in the last year.
But how do I check if a store has tunrover in both years during the load script?
I've had to compare week over week and week/day over week/day in the attached sample. You could also do the same for month. I used standard week conventions so I could compare the Monday of week 9 to the previous years Monday of week 9, etc.