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Klaus.Fliessbach | 10 Jan 14:01
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effects of interest in MarsBar

Hello to everyone and a happy new year!

I have run a second level RFX analysis set up with SPM5 for a ROI with MarsBar. It is a 3x3 two-factorial repeated measurements design.  When I plot the "effects of interest" via SPMgraphs, I get a plot of cbetas which looks quite different to a plot of the actual beta values. Obviously, however, the statistics are based on the betas (and not cbetas).

I do not exactly understand, how the "effects of interests" are calculated. The respective F-contrasts seems to weight the betas by some component of the covariance matrix. So I wonder:

1. What is the rationale behind this?

2. Does it make any sense to base a second level statistic on these contrast values (instead of "simple" contrasts)?

3. How can I extract or compute the data behind "cbeta", and what is its error?

Thanks,

Klaus


Dr. med. Klaus Fliessbach
Department of Epileptology
University of Bonn
Sigmund Freud-Str. 25
D-53105 Bonn
Germany 
0049-(0)228-6885264
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Anat Maril | 24 Jan 14:44
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hrf derivative timecourse

Hi,

We model the conditions in our fMRI experiment using the canonical hrf and

its first derivative. We would like to see the timecourses associated with

the derivative - does anyone know how to do that using MarsBar, or can

refer us to a piece of code that does that?

 

Thanks,

- anat

 
Anat Maril, Ph.D.
Department of Psychology
Department of Cognitive Science
The Hebrew University of Jerusalem
Jerusalem 91905
Israel
Tel: +972-2-5883302
marila <at> pluto.huji.ac.il 
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Tarimotimi T V Awipi | 25 Jan 04:05
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analyzing unnormalized data

Dear users,
We are trying to extract timecourses from unnormallized functional data using anatomical ROIs. We have
been using the marsbar batch script, and this crashes marsbar and matlab completely. We've been trying to
debug and have noted that the crash occurs during the "getdata" script. (although we're not sure that this
is the cause of the problem)
Can anybody offer suggestions on fixing this?
Thank you,
Tari Awipi

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Gmane