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st: checking model fit with svy estimation on


From   Cheney <furber.cini@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: checking model fit with svy estimation on
Date   Thu, 17 Feb 2011 15:20:06 -0800 (PST)

Hi,
I am having some troubles checking if my model is good (goodness of fit, no
influential outliers etc) and comparing model 1 to model 2 (with other iv's
or w iv's expanded), because of the limitations in stata for post est with
svy... 
(eg.   svy: logistic outcome iv1 iv2 iv3 iv4 iv5 iv1*iv3) My outcome is
binary and my IV's vary between categorical and binary (gender). I also know
you can test the model to see if you should have the iv's expanded into
dummy variables, I think you run one model, then another (with vars
expanded) then lrtest (I think- i haven't done it for a while) but you can't
do this with svy. I know you can do something with a wald test- but I don't
fully understand how to interpret that. Anyone have any suggestions? I need
a goodness of fit test... 

What I have done so far:
checked for interactions- found then added to the model.
checked for collinearity- found, centered vars and re ran model with
centered vars.
checked for outliers- (plotted pearson resid's) but I couldn't estimate
deviance residuals (because of svy) so I'm not sure if just one plot is
enough? I had only one outlier.
specification error- i did a linktest which gave me this output:
        _hat |   1.145419    .274488     4.17   0.000      .607336   
1.683502
      _hatsq |   .0298467   .0544568     0.55   0.584    -.0769059   
.1365993
which might mean that i don't have a problem with specification error. but I
wanted to do the 'boxtid' to check for non linear relationships, however
this is not supported with pweights... so I just ran the regression without
the svy etstimation and ran the boxtid. I ended up with non linear reasults
coming up, but none of them significant (in the example online they are
significant of course) so I didn't know if this meant they are non linear
but not to an extent that matters?
age      |   .4471324   .0736975      6.067   Nonlin. dev. 0.241   (P =
0.624)
       p1 |    2.85128   3.722516      0.766

Any other suggestions for checking the model is sound?
thanks in advance!
  
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