Ricardo Ovaldia wrote:
I was give the following SAS code and want to replicate in Stata. I am not sure
how to do this.
SAS code:
proc mixed data=nutrit.main covtest;
class ParticipantID Gender feedgroup;
model WeightAvgKg=Gender|feedgroup|Time GestAgeWks DietHxScore/solution ;
repeated / type=un subject=ParticipantID;
ods output Tests3=WeightAvgKg ;
run;
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Wouldn't it be something similar to the following?
xtmixed WeightAvgKg i.gender##i.feedgroup##c.Time c.GestAgeWks ///
c.DietHxScore || ParticipantID: , residuals(unstructured) t(Time) ///
variance nolrtest
For the Tests3 ODS option, you'll want to construct the contrasts yourself for
the so-called Type 3 tests of fixed effects. You can see how they're done at
www.stata.com/statalist/archive/2009-01/msg00172.html .
I think that COVTEST also prints out Wald tests for the variance components in
addition to Wald-based confidence intervals. I'm advised that these are best
considered as entertainment.
Joseph Coveney
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