[Marsbar-users] a question regarding P-value in marsbar

[Burak E. <bur...@gm...>]

Dear Matthew,

Sorry for sending this email directly to you rather than sending to list.

I recently performed an ROI analysis for my fMRI data (N=12) and used 12
ROI's in total (2 AAL, 2 self defined and 8 BGHAT).
and come up with several questions in mind, I will be glad if you can help
me answering them.

1st question is I tested each of the ROIs separately for a contrast (left
and right hemisphere ROIs separately)
Do you think I should have tested them in pairs (e.g.,left and right
putamen) or all of together?
What is the rationale for this, because it effects the significance
(corrected, uncorrected) ?.


2nd question, I found significant activity for 2 of the AAL ROIs when I
tested them separately.
the results were as follows where corrected and uncorrected equally. But
this is not corrected in the sense of FDR or FWE,
but based on the number of regions according to my understanding of marsbar
webpage. Now than, while writing
a paper I should put (p<0.05, uncorrected) is that right? and If thats
right, do you think this is an acceptable p value for ROI analyze?





Laterality

t-statistic

Corrected P-Value

Frontal_Med_ORB_L

L

2.2

0.029

Frontal_Med_ORB_R

R

2.67

0.014



Thank you very much
Best wishes


-- 
Burak Erdeniz
Psychology & Computer Science Department
Health & Human Sciences Research Institute
2f240 Health Building
University of Hertfordshire
College Lane
Hatfield
Herts
AL 10 9AB
omnia vincit amor