Trouble Replicating Unstructured Mixed Procedure in R
On Tue, 24 Jan 2012, Charles Determan Jr wrote:
Greetings, I have been working on R for some time now and I have begun the endeavor of trying to replicate some SAS code in R. I have scoured the forums but
This is also the Orthodont dataset, distributed with nlme. As David Atkins pointed out, R defaults to Type I SS. so you would need to use, for example, the Anova() command from the car package. The other thing is that the SAS F statistics are only approximate, depending on which covariance structure is chosen (perhaps John Maindonald or someone clever could comment), so SAS offers different possibilities for ddf eg http://www2.sas.com/proceedings/sugi26/p262-26.pdf while lme and lmer offer one or none.
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