Re: st: _00001 already define error using egen xx=group()

[Nick Cox <njcoxstata@gmail.com>]

An easy way to exclude B == 0 & D == 0 is

... if !(B == 0 & D == 0)

but this problem should still be fixed as soon as possible.

Nick

On Mon, Sep 26, 2011 at 8:32 AM, Barry Quinn <b.quinn@qub.ac.uk> wrote:
>
>  I have been running the egen xx= group() command to produce coding which allows me to choose 3 of the four possible pairs when combining two binary variables.
> Recently the above error has started to appear.
>
> Example:
>
> Say I have two binary variables D(0,1) & B(0,1)
> I want to run a command choosing the groups (D=0 & B=1) , (D=1 & B=0) , (D=1 & B=1) and not the group (D=0 & B=0).
> I find the egen group() command does this well by creating a variable from 1 to 4 for each possible combination of the two binary variables and then I run my command using
> ......if  xx>1
>
> My problem is when I run this command I get the error
> __000000 already defined
> __000001 already defined
>
> For reference here is the full code I am running and the resultant error:
>
> .clear
> . use panelcleanappend
> . capture drop w
> . gen w=runiform()
> . sort treat w
> . capture drop insample
> . gen insample=_n<=1000
> . drop id1
> . egen id1=group(insample oneyear)
> __000000 already defined
> __000001 already defined
>
> Any help with this error or a possible another way to choose the above groups would be appreciated
>

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