Hi,
I am trying to set up a longitudinal tbss analysis over 4 time points contrasting a patient
group to a control group. I'm interested in change over time rather than the effect of any
specifc time point. I was planning to model the slope for each subject and then put this
into a group t-test. Would modelling the slope for each subject be the same approach as a
simple correlation where my design matrix might look like this?:
-3
-1
1
3
Would this reflect the magnitude of the slope or does it only reflect the linearity like a
correlation coefficient? I would hypothesize that patients show a steeper slope than
controls though they may show more variability, so a least squares regression slope
might detect differences but a simple correlation coefficient might not.
Also, to perform a 2 level analysis with tbss is it preferable to use randomise and feed
the within subject t-stat into the group comparison or should I use the feat gui and treat
each within subject analysis as a timeseries and feed that into a higher level mixed
effects analysis?
thanks for all the help,
Kyle Kern
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