# st: benchmarking + determine the peers

 From "Bastian Steingros" To statalist@hsphsun2.harvard.edu Subject st: benchmarking + determine the peers Date Tue, 30 Sep 2008 16:32:36 +0200

```Dear Stata users,

I am searching a function in stata to program peer groups.
In my benchmarking study about American industries I want to compare companies by its sales, earnings etc.
I use the three digit industry code to classify the industries (sic-codes). The peer group must be within the same industry.
Here, the purpose is to compute the mean or median of the sales and to see if the respective firm's performance  is below or above the mean or the median.

But, the peer group of firm X contains all the companies with the same digit code but *not* firm X (otherwise I would compare X with itself)

To conclude:

year   sic-code firm  sales mean median
1990   333         X      10     ?         ?
1990   333         Y      20     ?         ?
1990   333         Z      30     ?         ?
---------------------------------------------
1990   334         A      21     ?         ?
1990   334         B       5      ?        ?
---------------------------------------------
1991   etc. ...

so, in 1990
the peer group mean/median for X must contain (20+30)  but not 10
the peer group mean/median for Y must contain (10+30)  but not 20
the peer group mean/median for Z must contain (10+20)  but not 30
and so on...

is there a way to program is stata something like:

by year sic-code, sort: egen median/mean *without the sales of the firm X / firm Y etc.*

(Please note, it is basically more important for me to obtain the *median* than the mean peer group due to the outlier problem of the mean function.)

Bastian

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```