[R] Repeated Measures/Linear Mixed Effects function

[Andrew Robinson]

Hi Keith,

it seems like a good starting position.  I recommend that you spend
some time studying Pinheiro and Bates's book to see where t ogo from
here.

Cheers

Andrew


On Mon, Oct 22, 2007 at 02:58:51PM -0800, Keith Cox wrote:
> I have three columns of data, Xc, Trt and fish.  This was a repeated
> measures design with 6 measurements taken from each of 5 fish.  Xc is the
> actual measurement, Trt is the treatment, and fish is the fish number.  Data
> can be seen below (hopefully it is in the column format).  I would like to
> look for differences between treatments in a repeated measures format.  I
> used the following code
> 
>  
> 
> library(nlme)
> 
>  
> 
> summary(lme(Xc~trt,data=R.exp,random=~1|fish))
> 
>  
> 
> This seems to work and I would like to know if
> 
>  
> 
> 1)    this is the right function for my question, if so, then
> 
> 2)    in the summary, value is the first column, but what value is this.  I
> have searched in vain and cannot find the answer.  Any help or links to
> examples would be appreciated greatly.
> 
> Fixed effects: Xc ~ trt 
> 
>              Value Std.Error DF   t-value p-value
> 
> (Intercept) 103.62  2.619657 20  39.55480       0
> 
> trtB        -33.28  1.991197 20 -16.71356       0
> 
> trtC        -39.38  1.991197 20 -19.77705       0
> 
> trtD        -32.60  1.991197 20 -16.37206       0
> 
> trtE        -47.32  1.991197 20 -23.76460       0
> 
> trtF        -39.58  1.991197 20 -19.87749       0
> 
>  
> 
> 
> Xc
> 
> Trt
> 
> fish
> 
> 
> 109.1
> 
> a
> 
> 1
> 
> 
> 73
> 
> b
> 
> 1
> 
> 
> 68.4
> 
> c
> 
> 1
> 
> 
> 74.8
> 
> d
> 
> 1
> 
> 
> 60.3
> 
> e
> 
> 1
> 
> 
> 57
> 
> f
> 
> 1
> 
> 
> 106
> 
> a
> 
> 2
> 
> 
> 72.3
> 
> b
> 
> 2
> 
> 
> 67
> 
> c
> 
> 2
> 
> 
> 70.6
> 
> d
> 
> 2
> 
> 
> 58.2
> 
> e
> 
> 2
> 
> 
> 66.2
> 
> f
> 
> 2
> 
> 
> 102
> 
> a
> 
> 3
> 
> 
> 67.1
> 
> b
> 
> 3
> 
> 
> 61
> 
> c
> 
> 3
> 
> 
> 68.4
> 
> d
> 
> 3
> 
> 
> 50.2
> 
> e
> 
> 3
> 
> 
> 64.7
> 
> f
> 
> 3
> 
> 
> 105
> 
> a
> 
> 4
> 
> 
> 76.6
> 
> b
> 
> 4
> 
> 
> 68.8
> 
> c
> 
> 4
> 
> 
> 77.7
> 
> d
> 
> 4
> 
> 
> 61.8
> 
> e
> 
> 4
> 
> 
> 75.7
> 
> f
> 
> 4
> 
> 
> 96
> 
> a
> 
> 5
> 
> 
> 62.7
> 
> b
> 
> 5
> 
> 
> 56
> 
> c
> 
> 5
> 
> 
> 63.6
> 
> d
> 
> 5
> 
> 
> 51
> 
> e
> 
> 5
> 
> 
> 56.6
> 
> f
> 
> 5
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> Marlin Keith Cox Ph.D.
> 
> At-Sea Processor Professorship of Fisheries Biology
> Science Chair
> 
> Sheldon Jackson College
> 
> Sitka, Alaska 99835
> 
> 907.747.5296
> 
> http://www.sheldonjackson.edu
> 
>  
> 
> 
> 	[[alternative HTML version deleted]]
> 
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-- 
Andrew Robinson  
Department of Mathematics and Statistics            Tel: +61-3-8344-9763
University of Melbourne, VIC 3010 Australia         Fax: +61-3-8344-4599
http://www.ms.unimelb.edu.au/~andrewpr
http://blogs.mbs.edu/fishing-in-the-bay/