Calculate averages in panel data file

[hahaha1241]

Hi,

I have panel data in Excel and need to calculate the average value of sales for every firm. It thus looks like this:

firm year sales average
1 1991 10
1 1992 12
1 1993 34
1 1994 19
1 1995 28
2 1991 51
2 1992 92
etc.

I want to calculate the average for every firm and put it in each of the boxes, something like this:

1 1991 10 20.6
1 1992 12 20.6
1 1993 34 20.6
1 1994 19 20.6
1 1995 28 20.6

Is there a way to easily accomplish this?

Thanks in advance,
hahaha1241

[AliGW]

How about this in D1, copied down?

=AVERAGEIF(A$1:A$7,A1,C$1:C$7)

Expand the ranges to suit.

[hahaha1241]

How about this in D1, copied down?

=AVERAGEIF(A$1:A$7,A1,C$1:C$7)

Expand the ranges to suit.

Thank you! I actually was playing around with the AVERAGEIF function already but could not make it work.

[AliGW]

You're welcome!

It's possible you didn't fix the lookup ranges before copying down: that's what the dollar sign does.