Re: [R] repeated measurements and lme

From: Dimitris Rizopoulos <dimitris.rizopoulos_at_med.kuleuven.be>
Date: Wed 15 Feb 2006 - 22:14:31 EST

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


>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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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Feb 15 22:33:11 2006

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