[R] repeated measurements and lme

[Dimitris Rizopoulos]

before fitting any model you should first think which is the question 
you want to answer; a possible model is:

fit <- lme(VCL ~ time * treatment + trail, random = ~ 1 | ID, data = 
within)

you don't have to use groupedData(); you can directly use lme().

note: you have also consider how you want to put 'time' in your model: 
factor or continuous?

I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://www.med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: <jonvaz at stud.ibg.uit.no>
To: <r-help at stat.math.ethz.ch>
Sent: Wednesday, February 15, 2006 12:02 PM
Subject: [R] repeated measurements and lme


>I am trying to do a repeated measurement anova using an lme. I have 
>the
>    following variables:
>    -ID, the identification of the individual
>    -trail, with 2 levels
>    -treatment, with 3
>    -time, measure 5 times the same individual
>    -VCL, the response variable
>    I tried the following in R,
>    within.gr<-groupedData(VCL~time|ID/treatment/time,data=within)
>    summary(lme(fixed=VCL~time*treatment,random=~1,data=within.gr))
>    I am not sure if it is correct at all. Can anyone help me? It 
> will be very
>    helpful.
>    Sincerely,
>    Jonathan
>
> Vaz
>
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