# Re: st: How to calculate mean of other individuals on the same group

 From "Quang Nguyen" To statalist@hsphsun2.harvard.edu Subject Re: st: How to calculate mean of other individuals on the same group Date Tue, 13 Feb 2007 20:15:37 -1000

```Dear Ryan,

Excellent! Thanks so much. I highly appreciate it.
Have A Wonderful Day!
Sincerely yours,

Quang

On 2/13/07, Ryan Herzog <rherzog@uoregon.edu> wrote:
```
```Quang Nguyen wrote:
> Dear all,
>
> A simplified version of my data looks as follows:
>
> ID      Group     X
> 1       a             5
> 2       a             7
> 3       a             9
> 4       a             8
> 5       b             3
> 6       b             4
> 7       b             9
> ..........................
>
> I would like to generate a new variable whose value is the average of
> other individual in the same group as the concerned individual. For
> example, for the first individual (ID=1), this will be: (7+9+8)/3= 8.
> For the 6th individual, this will be (3+9)/2=6 and so on.
>
> I would highly appreciate if someone could suggest me a solution for
> this.
> Thanks and Have A Great Day!
> Sincerely yours,
>
> Quang
> *
> *   For searches and help try:
> *   http://www.stata.com/support/faqs/res/findit.html
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
>
>
Generate the sum of each group: egen sum_var = sum(X), by(group)
Subtract the X value for that Id:  gen sum_less =  sum_var - X
Generate a count variable by group: egen count_var = count(X), by(group)
Subtract one from count, to exclude the ID's observation: gen count_less
= count_var - 1
gen mean_X = sum_less / count_less

Ryan
*
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*   http://www.ats.ucla.edu/stat/stata/

```
```*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```