Average Question, based on 2 to 3 sets of criteria.

[ExcelDude]

OK, I have a promotion begin date, and a promotion end date in 2 columns. I also have, say 50 columns with weekly sales data and a date heading. What I need to do is to average this data in 3 different areas. Avg before promo, during promo, and after promo. I also need it to average data that does not have a zero, which I believe I know how to do(=AVERAGE(IF(A2:A7<>0, A2:A7,""). Right now I'm manually averaging this data based on the different beg. and end dates, but it's a very manual process as the beg. and end dates very from title to title. Any ideas?

 

[NBVC]

Can't you use a similar Average(if formula and make the criteria <= cell with reference begin date, etc..?