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From | Lance Erickson <lance_erickson@byu.edu> |
To | "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |
Subject | st: Comparing coefficient across two xtmixed (growth curve) models |
Date | Tue, 23 Nov 2010 14:31:39 -0700 |
I am working with a panel dataset that has 4 measurement periods and estimating a mixed (growth curve) model using -xtmixed- where the dependent variable is nested within individuals. I want to compare a coefficient across two models where the only difference between the models is the introduction of an additional level-2 predictor. For example, the two models are specified like this... xtmixed y age x1 || id: age, cov(un) xtmixed y age x1 x2 || id: age, cov(un) Specifically, I want to test whether the estimate of x1 from the first model is significantly different than the estimate of x1 from the second model. I know I could 'eyeball' the difference but would feel better about interpreting them if there was a formal test. I understand that -suest- will not work in this situation because -predict- does not allow the -score- option after -xtmixed-. I haven't found a solution after various attempts at finding the answer through the statalist archives and alternative internet sources. Any direction or clues would be much appreciated. Thanks for considering the question, Lance * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/