You can do it to the sig file (the p-value already assumes a two-sided test). Why do you want to do it with the ces and cesvar files? If you are planning to use the abs(ces) for a higher level analysis then you need to be very careful as you can get some unintended effects doug

On 01/07/2014 03:46 PM, SHAHIN NASR wrote:

Hi, I have two related questions. I have two conditions (e.g. C1 and C2) and I want to generate a map that shows all voxels that can differentiate C1 from C2 _irrespective_ of whether C1>C2 or C1<C2. I think it can be done easily by:

mris_calc -o sig.nii abs_sig.nii abs

If I am right, then:

1. Can I apply the same command to ces.nii file to have the absolute

value of the effect size (i.e. abs(C1-C2 effect size)) or should I consider other factors? 2) Do I need to apply the same routine to cesvar?

Thanks

Shahin Nasr

PhD in Cognitive Neuroscience Martinos Imaging Center, MGH Harvard Medical School