Re: st: Pmatch2 and random

[Steven Samuels <ssamuels@albany.edu>]

This is expected behavior.  The fact that you randomly sorted the  
observations doesn't change the fact that some have the same  
propensity scores (often because the scores are based primarily on  
categorical variables so that there are many ties).
On Apr 13, 2007, at 5:26 AM, Gauri Khanna wrote:


> Dear Stata list,
>
> I am running the psmtach2 command to estimate propensity scores. I  
> use Stata 9.2 and psmatch2 is updated.
>
> While running this command, in my output I get a comment:
>
> "There are observations with identical propensity score values.
> The sort order of the data could affect your results.
> Make sure that the sort order is random before calling psmatch2"
>
> So I do the following
> -gen random=uniform()
> sort random-
>
> but still get the same message
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