Hi  Caroline


If your longitudinal study is unbalanced over time (ie. the timing of the serial measurements is different across subjects) and with such a relatively high amount of repeated measures (6) it is very likely that you will need a longitudinal linear mixed effects (lme) model  to properly analyze your data.  Repeated measures ANOVA is just a special case of an lme model with only a single random effect for the intercept term.


We have made available a link for anyone interested in downloading our Matlab-based lme toolbox that can be used to analyze Freesurfer Data.


You can find the lme tools here:

http://nmr.mgh.harvard.edu/~jbernal/

Please read the usage.txt file to get started with these tools. There are also some example data that can help you understand how to format your own data to work with these tools.

Best
-Jorge


De: Caroline Jiang <csjiang@hawaii.edu>
Para: freesurfer@nmr.mgh.harvard.edu
Enviado: Miércoles 17 de octubre de 2012 16:46
Asunto: [Freesurfer] Repeated measures ANOVA fsgd file

Hi,
 
I’m trying to set up my fsgd file for repeated measures ANOVA with two groups and 6 time points (0, 1, 2, 3, 4, 5) by following the example from here: http://surfer.nmr.mgh.harvard.edu/fswiki/RepeatedMeasuresAnova
 
Does this look correct for the fsgd file?  Subject 2 is missing time points 2 and 5.
 
GroupDescriptorFile 1







Title
RepeatedMeasures






Class
Group1






Class
Group2






Variables


TP0-vs-TP1
TP0-vs-TP2
TP0-vs-TP3
TP0-vs-TP4
TP0-vs-TP5
Input
subject1_tp0
Group1
1
1
1
1
1
Input
subject1_tp1
Group1
-1
0
0
0
0
Input
subject1_tp2
Group1
0
-1
0
0
0
Input
subject1_tp3
Group1
0
0
-1
0
0
Input
subject1_tp4
Group1
0
0
0
-1
0
Input
subject1_tp5
Group1
0
0
0
0
-1
Input
subject2_tp0
Group1
1
1
1
1
1
Input
subject2_tp1
Group1
-1
0
0
0
0
Input
subject2_tp3
Group1
0
0
-1
0
0
Input
subject2_tp4
Group1
0
0
0
-1
0
Input
subject3_tp0
Group2
1
1
1
1
1
Input
subject3_tp1
Group2
-1
0
0
0
0
Input
subject3_tp2
Group2
0
-1
0
0
0
Input
subject3_tp3
Group2
0
0
-1
0
0
Input
subject3_tp4
Group2
0
0
0
-1
0
Input
subject3_tp5
Group2
0
0
0
0
-1
 
 
I’m interested in the overall group effect [1 -1 0 0 0 0 0 ], overall time effect, and group-x-time interaction.
 
Is this the correct contrast for the overall time effect?
0 0 1 0 0 0 0
0 0 0 1 0 0 0
0 0 0 0 1 0 0
0 0 0 0 0 1 0
0 0 0 0 0 0 1
 
What would be the contrast for group-x-time interaction?
 
 
Thanks!
Caroline
 

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