Dear Jeanette,
Thank you very much for the feedback! This sounds indeed logical.
How can I subtract the pre from the post scan?
Thanks again!
Best
Heidi
________________________________________
Van: FSL - FMRIB's Software Library [[log in to unmask]] namens Jeanette Mumford [[log in to unmask]]
Verzonden: maandag 24 september 2012 16:35
Aan: [log in to unmask]
Onderwerp: Re: [FSL] Repost: question regarding pre and post comparison
Hi,
Yes, to test how the pre/post differences compare between your two groups, you would first subtract the pre/post within subject and then enter these differences into a 2-sample t-test.
Other within pre or within post difference between your groups would be run with separate two-sample t-tests.
Cheers,
Jeanette
On Mon, Sep 24, 2012 at 3:35 AM, Jacobs H (NP) <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Dear FSL team,
I am struggling a bit with the statistics for my resting state analyses.
I have two groups (each 20 subejcts) and a pre and post measurement. I already ran the ICA and now would like to do the dual regression.
In this regression I would like to investigate the main effect of group, condition (pre/post) and the interaction (group differences on the difference between post and pre).
Should I do a 2by2 anova with 4 EV's (group1 timepoint 1; group 1 timepoint 2; group 2 timepoint 1; group 2 timepoint 2).
And then create the following contrast file
main effect group: 1 1 -1 -1
main effect time 1 -1 1 -1
interaction: 1 -1 -1 1
However, I read somewhere that I should subtract both conditions for each individual and then compare the two group on this 'subtracted image'??
Is this correct?
Any advice would be greatly appreciated!!
Thanks!
Best
Heidi
================================================
Dr. Heidi Jacobs
Postdoc researcher
Faculty of Health, Medicine and Life Sciences
School for Mental Health and Neurosciences
Division Cognitive Neuropsychiatry and Clinical Neurosciences
Alzheimer Center Limburg
[log in to unmask]<mailto:[log in to unmask]>
www.maastrichtuniversity.nl<http://www.maastrichtuniversity.nl>
www.heidijacobs.nl<http://www.heidijacobs.nl>
Dr. Tanslaan 12, 6229 ET Maastricht
P.O. Box 616, 6200 MD Maastricht, The Netherlands
T +31 43 38 84 090<tel:%2B31%2043%2038%2084%20090> F +31 43 38 84 092<tel:%2B31%2043%2038%2084%20092>
================================================
|