[R-sig-ME] (no subject)

Adewale, Adeniyi adeniyi_adewale at merck.com
Wed Jun 1 19:59:51 CEST 2011

Does anyone know how to fit a repeated measures model in R with
unstructured variance-covariance matrix? Below is a SAS equivalent of
the model I am interested in:

proc mixed data=longdat;
	class alloc week;
	model y =  week  trt2wk1 trt2wk2 trt2wk3 trt2wk4/ddfm=kr covb
corrb solution;
	repeated week/type=un subject=alloc;

I was able to fit a simpler model with compound symmetric
variance-covariance structure (or equivalently, for positively
correlated data, a simple random intercept model) using the lme function
in the nlme package:

fit <- lme(y ~ week + trt2wk1 + trt2wk2 + trt2wk3 +

My example data is attached.

Adeniyi Adewale

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