Usually when this happens to me, it's because I have all missing or
all one value (i.e., 0 or 1) in one or two variables. This leads to
tabulating each variable, and tabulating two-way for each two-way
combination.
Joel
Joan Holand writes:
> Dear statalist,
>
> I'm running a loglinear model using the -glm- command (Stata 9SE,
> Windows XP):
>
> glm depvar a*b*c*d, fam(pois)
>
> I'm specifying 4-way-interactions but unfortunately some of the
> coefficients are beeing dropped because of the collinearity. I'm sure
> that I did not use the same variables twice.
>
> Assuming that my model is ok. :-) , what could be other possible reasons
> for dropping coefficients?
>
> Thank you very much for any comments!
> Joan
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
--
Joel J. Adamson
Biostatistician
Pediatric Psychopharmacology Research Unit
Massachusetts General Hospital
Boston, MA 02114
(617) 643-1432
(303) 880-3109
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