[R] treatment effects with lme (repeated measurements)
steffen.fleischer at medizin.uni-halle.de
Fri Dec 3 09:12:49 CET 2010
I want to analyze an outcome in an RCT using lme but I am not sure that I have chosen the right way for the model.
We measured the outcome three times repeatedly in the same patient. One time before intervention and two times after intervention. I wanted to adjust for the correlated data in the repeated measurement and baseline differences in the variable in order to get the treatment effect.
Here the model:
for the data structure:
id time outcome baseline treatment
1 1 10 5 1
1 2 12 5 1
alternatively I could use 3 rows per participant, omitting baseline as a variable as it would be included in "outcome" and "time" then.
The model then would be:
I am not sure which way is better/right or if there is a third alternative for this problem.
Thanks in advance
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