Re: st: merge command doesn't work???

[David Kantor <kantor.d@att.net>]

At 02:11 PM 8/28/2008, Kokootchke (Adrian) wrote:
> It is more likely that I am the one who doesn't work, but I don't 
> understand what I'm doing wrong.
>
> I have a dataset that looks like this:
>
> sic87 isic3
> ...
> 3199 1810
> 3199 1912
> 3199 1920
> 3199 3699
> ...
> 2021 1520
> 2022 1520
> 2022 1549
> 2023 1520
> 2024 1520
> 2026 1520
> ...
>
> and another one that looks like this:
>
> sic87 year emp
> 3199 1980 50
> 3199 1990 70
> 3199 2000 85
> 2021 1980 57
> 2021 1990 65
> 2021 2000 95
> 2022 1980 17
> 2022 1990 23
> 2022 2000 25
> ...
>
> If I sort both datasets by sic87, start with the second one and type:
>
> merge sic87 using firstdataset
>
> shouldn't I get something that looks like this:
>
> sic87 year emp isic3
> 3199 1980 50   1810
> 3199 1980 50   1912
> 3199 1980 50   1920
> 3199 1980 50   3699
> 3199 1990 70   1810
> 3199 1990 70   1912
> 3199 1990 70   1920
> 3199 1990 70   3699
> ...
>
> that is, because I am not specifying that the observations in either 
> the master or the using data sets should be unique, then stata 
> should expand my master data set, repeating every row in the master 
> data set for every repeated row in using data set with same sic87 
> but different isic3, no?
>
> I know this has to do with how stata handles the unique values in 
> both the master and the using data sets, but I don't know what's going on.
>
> I hope you guys can tell me what I'm doing wrong.
Use -joinby- rather than -merge-.
HTH
--David

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