# sign of the T-values in permutation\_cluster\_test **URL:** \ **Category:** Mailing List Archive (read-only)\ **Tags:** list-archive\ **Created:** [May 7, 2020, 3:09pm UTC](https://mne.discourse.group/t/sign-of-the-t-values-in-permutation-cluster-test/2186 "2020-05-07T15:09:45Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [May 7, 2020, 3:09pm UTC](https://mne.discourse.group/t/sign-of-the-t-values-in-permutation-cluster-test/2186/1 "2020-05-07T15:09:45Z")
External Email - Use Caution Dear MNE community, I'm using permutation\_cluster\_test for 2 sample cluster-based tests. I'm quite surprised because I always get positive T-values, even when I expect negative ones. Reversing the order of the 2 arrays (one for each group) yields exactly the same result. Is this normal ? -------------- next part -------------- An HTML attachment was scrubbed... URL: [http://mail.nmr.mgh.harvard.edu/pipermail/mne\_analysis/attachments/20200507/24a3e822/attachment.html](http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20200507/24a3e822/attachment.html) ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [May 7, 2020, 3:15pm UTC](https://mne.discourse.group/t/sign-of-the-t-values-in-permutation-cluster-test/2186/2 "2020-05-07T15:15:21Z")
External Email - Use Caution What `stat_fun` are you using? The default (f\_oneway / ANOVA) will always give a positive F value. Maybe you want to use `ttest_ind_no_p` that was recently added here? [https://github.com/mne-tools/mne-python/pull/7686](https://github.com/mne-tools/mne-python/pull/7686) Eric