 |
 |
Hi Steve, Thank you for your response! I have further clarification questions regarding your reply to my third question. 1) Do I select the “cluster” option under “Thresholding”? I tried both “voxel” and “cluster”, but I get the web report table only when I selected “cluster”, so I hope this is right. (By the web report table, I mean the table you see in “cluster_zstat1_std.html”. Is this right?) 2) By loading the thresh_zstat image onto FSLView, should I be able to change the threshold by changing the number number in the Min (and Max) window just above the images? It doesn’t let me change threshold in FSLView, so I’m assuming that this is not possible. 3) In the Cluster List in the“cluster_zstat1_std.html”, I see Z-MAX. Are these z-values directly translatable into p-values? In other words, if I see Z-MAX > 2.3, are the corresponding p-values < .01? Thank you in advance for taking time to reply! -Yoshiko On Tue, 15 Jan 2008 06:23:54 -0000, Stephen Smith <[log in to unmask]> wrote: > Hi, > > > I have a few basic questions for clarification about FEAT post-stats. > > > > 1) At each level of analysis, FEAT gives you tstat.nii.gz and zstat.nii.gz > > in the stat folder. Are > > activations you see in these files not corrected for multiple comparisons? > > These t and z-statistic images not p-value images are not even > thresholded, so no they are not corrected for multiple comparisons! > > > 2) Do you have to choose either the voxel-wise or cluster-wise > > thresholding in the FEAT post-stats > > tab to have correction applied? > > Indeed - that's right. > > > 3) Does FEAT give you a zstat.nii.gz file which contain stats that are > > unthreholded but corrected for > > multiple comparisons that we can load onto FSLView and look at activations > > at different thresholds? > > yes - you can set the p-value threshold to 1 so that no thresholding is > done - then you can look at the "thresh_zstat" images in conjunction with > the web report tables to see the (GRF-corrected) p-values. > > Cheers. > > > > > Thank you very much in advance for your information! > > > > -Yoshiko > > > > >