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From | Grethe Søndergaard <dkstatstata@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | st: Small strata and test of proportional hazard assumption |
Date | Thu, 16 Dec 2010 10:24:11 +0100 |
Hello, I am analysing my data using a stratified cox-regression and am trying to find out if the proportional hazards assumptions in my model is violated. I wanted to test this using the command estat phtest. However, I have become aware that you cannot do this, when the stratas are very small (each of the stratas contains 2-6 individuals). I haven’t been able to find any information about how to test the PH assumption when you have very small strata. Does anyone know of such test? (Otherwise I am thinking about first running the full model. Afterwards I could stsplit my data in two, and run these models. By lrtest I could probably test whether there is better goodness of fit in the two time-specific models compared to the full model). Grethe * * 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/