I'm trying to make a formula dynamic. I have data rows by date. I have a formula that will look at every 7'th column so that I can average, for example, performance on Mondays.

Here is my formula:
=AVERAGE(IF((DataInput!$F$41:$GJ$43<>"")*(MOD(COLUMN(DataInput!$F$41:$GJ$43),F3)=F2),DataInput!$F$41:$GJ$43))

What I'd like to do is adjust the beginning and end dates specified by the "DataInput!$F$41:$GJ$43" portions of the formula.

I've entered a data "List" and can look up the column using VLookup function. But I'm having some difficulty putting it all together. Any ideas? Your help would be greatly appreciated!