
Hello everybody, 


A statistician performed an analysis in SAS for me which I would like to replicate in R.
I have however problems in figuring out the R code to do that.


As I understood it was a "covariance regression model". In the analysis, baseline was used as covariate and autoregressive (1) as covariance structure. The model included baseline, session, group and interaction between baseline and group. The degree of freedom  was corrected by Kenward-Roger method.


Study design:
- 2 Groups: group A: n=10 subjects, group B: n=10
- 5 motor test: baseline; learning sessions immediately, 6h, 24h, and 30d after memory task
- dependent variable: response time (RT)
Research question: Do the two groups learn differently across time?


I would appreciate a lot any help on the R commands or the choice of statistical approach.


Thanks!
Marianne, Columbia, SC

 		 	   		  
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