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Re: st: Creating a mean of x entries in variable1 if there are at least x entries in variable1 by person id
From
Roberto Ferrer <[email protected]>
To
Stata Help <[email protected]>
Subject
Re: st: Creating a mean of x entries in variable1 if there are at least x entries in variable1 by person id
Date
Wed, 9 Oct 2013 06:04:26 +0100
*----------------------------- input -------------------------------------------
clear
input id exposure year
1 3 1
1 3 2
1 4 3
1 3 4
1 3 5
2 4 1
2 4 2
2 3 3
2 4 4
3 1 1
3 2 2
3 3 3
3 2 4
4 1 1
4 3 2
end
*---------------------- what you want ------------------------------------------
bysort id: gen count = _N
collapse (mean) exposure if count >= 3, by(id)
*-------------------------- end ------------------------------------------------
See also:
http://www.stata.com/support/faqs/data-management/number-of-distinct-observations/
On Wed, Oct 9, 2013 at 1:07 AM, Nicholas Winters
<[email protected]> wrote:
> Sorry for the complicated subject, this is what my data looks like:
>
> person id exposure year
> 1 3 1
> 1 3 2
> 1 4 3
> 1 3 4
> 1 3 5
> 2 4 1
> 2 4 2
> 2 3 3
> 2 4 4
> 3 1 1
> 3 2 2
> 3 3 3
> 3 2 4
>
> I want to take an average of 'exposure' if there are at least, say, 3 entries in 'year' per person id. So I want to end up with a new variable, mean_exposure, that looks like this:
> person id mean_exposure
> 1 3
> 2 4
> 3 3
> 4 2
>
> I've tried by person id: egen mean_exposure=mean(exposure) if _____________
> but I want the mean of ALL values in exposure only if 'year' has at least x number of observations
> please help, I'm stumped...?
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/faqs/resources/statalist-faq/
> * http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/faqs/resources/statalist-faq/
* http://www.ats.ucla.edu/stat/stata/