Re: st: suest after svy:clogit

[Klaus Nowotny <klaus.nowotny@sbg.ac.at>]

Dear Maarten,

thanks for the answer and the hint comcerning the iweights. But changing 
svyset to

svyset id [pw=weight]

does not solve my initial problem. I've already estimated the model 
using interactions, but it would have been interesting to know why I get 
the "option cluster() is not allowed"-error.

In any case, thanks a lot!
Klaus

Am 17.05.2013 13:14, schrieb Maarten Buis:

> On Thu, May 16, 2013 at 6:31 PM, Klaus Nowotny wrote:
> > I am having troubles using suest to test the equality of coefficients across
> > two groups after svy:clogit. My survey data is set up as follows:
> >
> > svyset id [iw=weight]
> To quote -help weight-: "iweights, or importance weights, are weights
> that indicate the "importance" of the observation in some vague sense.
>   iweights have no formal statistical definition; any command that
> supports iweights will define exactly how they are treated.  Usually,
> they are intended for use by programmers who want to produce a certain
> computation."
>
> So using iweights for a statistical analysis is almost certainly a mistake.
>
> > I then estimate the model for two subgroups:
> >
> > svy, subpop(if group==1): clogit choice x1 x2, group(id)
> > est sto group1
> > svy, subpop(if group==2): clogit choice x1 x2, group(id)
> > est sto group2
> >
> > To test for the equality of the coefficients of x1 across the two groups I
> > follow the Stata reference manual for suest and enter
> >
> > suest group1 group2
> >
> > but Stata returns "r(198); option cluster() is not allowed with svy results"
> > although I never entered the cluster option anywhere.
> Why not just estimate the entire model in one go?
>
> svy : clogit choice i.group##(c.x1 c.x2), group(id)
>
> Hope this helps,
> Maarten
>
>   The same occurs if I
> > try the alternative procedure suggested in the reference manual:
> >
> > clogit choice x1 x2 if group==1 [iw=weight], group(id)
> > est sto group1
> > clogit choice x1 x2 if group==2 [iw=weight], group(id)
> > suest group1 group2, svy
> >
> > Why do I keep getting this error message? Any help would be greatly
> > appreciated!
> >
> > Thanks,
> > Klaus
> >
> > --
> > Klaus Nowotny
> > University of Salzburg
> >
> > *
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>
>
> --
> ---------------------------------
> Maarten L. Buis
> WZB
> Reichpietschufer 50
> 10785 Berlin
> Germany
>
> http://www.maartenbuis.nl
> ---------------------------------
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*
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