Mean of a group minus the observation's value in Panel data

[Ece Kural]

Hi,

I have a data structure like this:

IO-IOarea-Year-index
1----4-------1997-0
2----4-------1998-2.2267373
3----5-------1998-0
4----5-------2000-0

I would create a mean of index variable for each IOarea group per year. So I used this code:
by IOarea Year, sort: egen index_byissue=mean(index)

However, now I would like to add a second step where I show the mean of the group minus that IO's score per year. So each IO get the score of index_byissue minus its own score each year. I aim to use other group members' average score each year as a new variable.

Thanks so much by now!

[Nick Cox]

Often discussed here. See FAQ on results for other members of a group on the Stata website and also rangestat or asrol from SSC.