st: Survey design degrees of freedom help

[Jennifer Schmitt <jorg0206@umn.edu>]

Hello everyone,
I need some important clarification about the design degrees of freedom 
for stratified clustered survey analysis.  I have data that was 
stratified by three areas (NW, SW, and E).  We randomly chose villages 
from these three areas, then chose 5 subvillages within the village and 
within the subvillage we chose households (the unit of interest for my 
analysis).  I am running logistic regressions with PSU = village, strata 
= area and probability weights.  My design degrees of freedom are 16 
(PSU-strata-one for the constant term).  I get that.  What I do not 
understand is WHY and how to explain to others unfamiliar with STATA 
that it is correct, any answers to this would be greatly appreciated.  
The reason this is an issue is that I want to test more than 16 
variables at once and obviously I can't with only 16 df.  Thank you.
Jennifer

--
Jennifer Schmitt
PhD Candidate - Conservation Biology Program
University of Minnesota
jorg0206@umn.edu

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