Hello all,
I will first start with what we have:
Within an fmri study,
One group
Five subjects
Two conditions
Auditory Monitoring versus its own baseline
Working Memory versus its own bbaselineaselinebaseline
Two nuisance variables
anxiety score (one score per subject)
Depressive mood score (one score per subject)
One covariate of interest
error score on the working memory task
This is what we did
Design Description
Desgin: Full Monty
Global calculation: mean voxel value (within per image fullmean/8 mask)
Grand Mean scalingL (implicit in PropSca global normalization)
Global normailzation: proportional scaling to 50
Parameters: 2 condition, +1 covariate, +5 block, +2 nuisance
10 total, having 7 degrees of freedom
leaving 3 degrees of freedom from 10 images
Is this a valid way of looking at this?
We are concerned with the large degrees of freedom that we are using up.
Also how would we accurately interpret such a model? Does the statistical
map only represent activations that are associated with the covariate of
interest after controlling for anxiety and depression scores?
Looking at the covariate of interest only with the contrast (0 0 1 ...)
What does it mean, what is it showing us? Do we interpret this contrast by
itself or is its information contained with the contrast: (-1 +1 0 ...)?
We also have a second group of subjects consisting of six subjects having
the same conditions and subject measures. We are interested in looking at
each group seperately and between groups.
thank you,
Dr. Lange and Jason.
Jason R. Steffener, RTSV
Department of Psychiatry, University Hospital, UMDNJ
Office: (973) 972-1604
http://www.umdnj.edu/~steffejr/jason.html
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