Re: st: First occurence

[Joseph McCrary <joe.mccrary@gmail.com>]

sort idcode year
by idcode: egen yrcount=seq()

Then, when yrcount is 1 will be the first year the idcode appears.



Meryle Weinstein wrote:
> I've tried following the syntax in FAQ and archives but am having difficulty
> with it.  I have a dataset that has an idcode and a year for a number of
> schools.  I want to identify the first year that the idcode appears.  I've
> tried the following but still don't' get the first occurrence.
>
> by bdsmaster (year), sort: gen noccur = sum(bdsmaster)
> by bdsmaster: gen byte first = noccur == 1  & noccur[_n - 1] != noccur
>
> gen byte first = sum(bdsmaster == 1) == 1  & sum(bdsmaster[_n - 1] == 1) ==
> 0  
> Thanks for your help.
>
> Meryle Weinstein
> Research Scientist
> Institute for Education & Social Policy
> New York University
> Pless Hall
> 82 Washington Square East, 7th floor
> New York, NY 10003
> (212) 998-5817
> (212) 995-4564 (fax)
> www.steinhardt.nyu.edu/iesp
>
>
>
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