Dear FSL experts,
I would like to test longitudinal data for a linear (or possibly quadratic) effect over time. Some subjects have been scanned two times, some three times and some four times. A first level analysis has been performed with a customized bash script, and the result for each subject and timepoint is now taken to a second level analysis. I would like to investigate if any parts of the brain are linearly affected as function of the time after injury (rather than an ordinary t-test between different timepoints). How do I setup this testing with randomise?
Let's say I have data from 5 subjects. Subjects 1 and 2 were scanned four times, subject 3 and 4 three times and subject 5 two times.
I use two regressors in the design matrix, one for the mean and one for the number of days between the injury and the scan. Each subject belongs to one group.
Group EV1 EV2
1 1 10
1 1 25
1 1 55
1 1 85
2 1 8
2 1 29
2 1 58
2 1 85
3 1 2
3 1 34
3 1 66
4 1 5
4 1 45
4 1 80
5 1 6
5 1 60
The design matrix is simply the two regressors, and design.grp is the group column.
I want to test if the linear effect is significant, so the t-contrast is 0 1.
The input to randomise is one 4D file where the order of the volumes matches the group column.
Can anyone verify if this is correct?
cheers,
Anders
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