 |
 |
Hello FSL users My question is regarding the usage of randomise with the '--vxl' and '---vxf' options, when using lesion masks to exclude voxels in a group comparison I am using randomise to test at each voxel whether the control group (n=16) has a higher intensity value (for our biomarker) than chronic stroke participants (n=18). I would like to use lesion masks as described in the Associated Tools section under the randomise user guide (https://fsl.fmrib.ox.ac.uk/fsl/fslwiki/Randomise/UserGuide#Associated_Tools). I used 'setup_masks' as instructed, which created: >> a 4D image of my lesion masks (34 volumes for my 34 subjects), where the first 16 volumes are a 'zero' image, and the next 18 volumes contain '1's where the stroke participant has a lesion. >>a *.mat file, where the first two columns are set-up according to the GLM page on "Two-Group Difference (Two-Sample Unpaired T-Test)" (https://fsl.fmrib.ox.ac.uk/fsl/fslwiki/GLM#Two-Group_Difference_.28Two-Sample_Unpaired_T-Test.29), and the next 34 columns create a 34x34 matrix with ones along the diagonal. This is attached at the lesionMask.mat file--hopefully. >>a *.con file, where the first two columns are set-up according to the GLM page on "Two-Group Difference (Two-Sample Unpaired T-Test)" (https://fsl.fmrib.ox.ac.uk/fsl/fslwiki/GLM#Two-Group_Difference_.28Two-Sample_Unpaired_T-Test.29), and the next 34 columns create a 2x34 matrix with all zeros. This is attached at the lesionMask.con file--hopefully. After running the setup_masks command, it outputs an example randomise command, with the suggested 'vxl' = - 3 and 'vxf' = my 4D lesion mask image. My question is: how do I interpret the suggested value of -3 which, according to the randomise usage, it is a "list of numbers indicating voxelwise EVs position in the design matrix" I would appreciate any help in the interpretation. Thank you - Miguel ######################################################################## To unsubscribe from the FSL list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=FSL&A=1