[R-sig-ME] AR(1) structure with Satterthwaite correction

j.zavrakidis at nki.nl j.zavrakidis at nki.nl
Fri May 4 23:01:48 CEST 2018

Dear all,

I have a question which is half theoretical and half practical. 
I am working on longitudinal datasets with small sample sizes, which i analyze with mixed models. Now, i am aware of the possible corrections in such cases, Satterthwaite and Kenward-Rodger. I am also aware of the different covariance structures that you  can impose in the level-1 variance. 
And here comes my question: Can we combine these 2 ??
That is, when we are talking about longitudinal data it is very possible that measurements closer in time are more correlated than those who are further apart, and the AR(1) is a potential covariance structure. Hence, can i have a model where the residuals  are autocorellated for instance and at the same time I apply the Satterthwaite correction for the df's and consequently for the inferences of the fixed effects ? 
If the answer to that question is yes (as I assume it is), how can I do that in R ? I know that for the AR(1) structure i have to use the nlme package, and for the Satterthwaite correction the lmerTest package which actually uses the lmer package. Do i miss a package or an update to the previous that make the combination possible?
P.S. I found the following paper where they combines these 2 'techniques' in SAS...
Kind regards,
John Zavrakidis
Junior Researcher - Statistician
Department of Epidemiology and Biostatistics
e-mail:  j.zavrakidis at nki.nl

The Netherlands Cancer Institute | Plesmanlaan 121 | 1066 CX AMSTERDAM | www.nki.nl

This e-mail is intended for the addressee(s) eyes only. If you are not the intended recipient, you are hereby kindly requested to inform the sender of this. In view of the electronic  nature of this communication, The Netherlands Cancer Institute (NKI) is neither liable for the proper and complete transmission of the information contained therein nor for any delay in its receipt. For information about the Netherlands Cancer Institute, go  to www.nki.nl.
Dit e-mailbericht is uitsluitend bestemd voor de geadresseerde(n). Als dit bericht niet voor u bestemd is, wordt u vriendelijk verzocht dit aan de afzender te melden. Het  Antoni van Leeuwenhoek  (AVL) staat door de elektronische verzending van dit bericht niet in voor de juiste en volledige overbrenging van de inhoud, noch voor tijdige ontvangst daarvan. Voor informatie over het AVL raadpleegt u www.avl.nl

More information about the R-sig-mixed-models mailing list