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Re: st: merging datasets and getting different N in resulting dataset if I run several times


From   Austin Nichols <austinnichols@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: merging datasets and getting different N in resulting dataset if I run several times
Date   Fri, 14 Aug 2009 10:44:20 -0400

Woolton Lee<finished07@gmail.com> :
Probably due to unstable sorting; without further info, hard to diagnose.
Do you have missing values in any of the merge vars?
This is a potentially very serious problem; see e.g.
#4 in http://www.princeton.edu/~jrothst/hoxby/rejoinder.pdf

On Fri, Aug 14, 2009 at 10:28 AM, Woolton Lee<finished07@gmail.com> wrote:
> Hi I am getting a problem where I am merging two datasets together and
> the N in the resulting dataset can change if I rerun the program 2 or
> more times.  I am merging by company code (COCODE) and year which do
> not uniquely identify observations in the using dataset, but it seems
> to me that that should not matter.  I get the same result if I use the
> joinby command - the resulting N in the dataset changes if I rerun the
> program.  I am trying to understand why this might happen and am
> stumped at the moment.  Does anyone have any suggestions?
>
> W

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