 |
 |
Hi. I use afni, so i cannot comment on which program is better. 3dAlphaSim (an older version of 3dClustSim) required inputting the size of the gaussian kernel (in mm, FWHM) used to smooth the data at the single subject level. The cluster size (in original sized voxels, before resampling) would depend on such factors as initial thresholding and the significance level of the mulitple comparisons correction. Hope this helps. ________________________________________ From: FSL - FMRIB's Software Library [[log in to unmask]] on behalf of Torsten Ruest [[log in to unmask]] Sent: Wednesday, November 23, 2011 8:35 AM To: [log in to unmask] Subject: [FSL] data smoothness and corrections.... Hi there, I'd like to use afni's 3dClustSim to identify the minimum cluster size for our seed ROI resting state analyses. It asks for the FWHM of the data, so I thought computing it from the group analysis smoothness file according to FWHMav = (resels * pixdim1*pixdim2*pixdim3)^(1/3); which in standard space would be (310.004*2*2*2)^(1/3) = 13.5359 Does this sound correct (we used an 8 mm kernel at the 1st level)? Would randomise be a better alternative instead of using a cluster extent threshold? Thanks again for all comments ! Cheers, Torsten The information in this transmission is intended for official use of the Kessler Foundation. It is intended for the exclusive use of the persons or entities to which it is addressed. If you are not an intended recipient or the employee or agent responsible for delivering this transmission to an intended recipient, be aware that any disclosure, dissemination, distribution or copying of this communication, or the use of its contents, is strictly prohibited. If you received this transmission in error, please notify the sender by return e-mail and delete the material from any computer.