# Re: st: calculate the average by subgroup for a panel dataset

 From Scott Merryman To statalist@hsphsun2.harvard.edu Subject Re: st: calculate the average by subgroup for a panel dataset Date Wed, 29 Jul 2009 15:13:39 -0500

```-egen ave = mean((s1 + s2  + s3)/3), by(zip)-

Scott

On Wed, Jul 29, 2009 at 3:02 PM, HSIUTZU CHANG<hschangbetty@gmail.com> wrote:
> ---------- Forwarded message ----------
> From: HSIUTZU CHANG <hschangbetty@gmail.com>
> Date: Wed, Jul 29, 2009 at 2:48 PM
> Subject: calculate the average by subgroup for a panel dataset
> To: statalist@hsphsun2.harvard.edu
>
>
> Dear Stata users:
>
> How can I calculate the average of serveral variables by the subgroup
> of another variable?
> I have a panel dataset of property sale price information and I need
> to calculate the average of the sale prices (s1, s2, s3) by zipcode
> area (zip).
>
> Since there are missing values in my dataset, I have tried using a
> command suggested from an eariler thread
> http://www.stata.com/statalist/archive/2007-02/msg00143.html
>
> egen ave= rmean(s1-s3)
>
> but this command only calculate the average of s1-s3 for each record.
> In order to calculate the average of s1-s3 by zip, I tried:
>
> bysort zip: egen ave2= rmean(s1-s3)
>
> I got an error messaging saying
> " egen ... rowmean() may not be combined with by
> r(190)"
>
> I am a beginer to STATA, so any suggestions will be welcome!
> Thank you
>
> Betty

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