Formulae - variable cell reference

[thunderfoot]

I have a column of about 600 numbers, say recorded in column 'A' (recorded Odds from a Betting site in 1 second intervals). To one side of this column I want a 'Running Average' based over the last 'x' numbers.

Obviously I can use =AVERAGE(A1:A50) in cell B51 and =AVERAGE(A2:A51) in cell B52 etc. etc by just copying the formulae down column 'B'.

However, I want to experiment and find out "should I use the last 50 numbers or the last 'x' numbers".

To do this I could just change the formulae in column 'B', BUT is there a way to do the following?

In a cell, say C1, enter a number 20, then the AVERAGE formuale would use the last 20 numbers; if I changed the number in cell C1 to 10 then the AVERAGE formulae would use the last 10 numbers etc. etc. thereby somehow using the number entered in cell C1 to determine over how many numbers in column 'A' are used to calculate a 'Running Average'.

 

[Andrew Poulsom]

In B51 it would be:

=AVERAGE(A51:OFFSET(A51,-C$1+1,0))