st: suest after svy:clogit

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

Dear statalist users,

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]

where "id" identifies a specific combination of individual 
characteristics and "weight" is the weight attached to the observation. 
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. 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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