Hi all,
I used randomise to perform a two sample t-test on the group of maps.
I used the -D option since I don't model the mean in my design matrix.
(i.e. having a column of all '1's in the design matrix). However, I
received the following warning message when I run randomise
Warning: You have demeaned your data, but at least one design column
has non-zero mean
I am confused since the design columns are used to model the
difference between two groups hence they have one-zero mean by nature,
does this have anything to do with modeling the mean of the entire
data (group1 + group2)?
My design matrix is shown as below.
Please kindly advise.
Best,
Leo
> more design.mat
/NumWaves 2
/NumPoints 26
/PPheights 1 1
/Matrix
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
more design.con
/NumWaves 2
/NumContrasts 2
/PPheights 1 1
/Matrix
1 -1
-1 1
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