AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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RWCox
April 01, 2021 11:35AM
  • It is correct that [0] and [1] are the mean of arctanh(correlation) and the Z-statistic/score of how far that mean is from 0.
  • However, it is not true that [2] is "the mean of correlation" -- it is the tanh(mean of arctanh(correlation)) -- which is somewhat different.
  • For example, take 3 values = 0.3, 0.6, 0.9, whose mean is obviously 0.6. However, the following calculation (using AFNI's ccalc program) gives 0.677762 instead: 
      ccalc 'tanh((atanh(0.3)+atanh(0.6)+atanh(0.9))/3)'
    Which shows that the "stretching out" action of arctanh gives more weight to larger correlation values.
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Subject Author Posted

Output of 3dGroupInCorr

s.meliss March 31, 2021 07:01AM

Re: Output of 3dGroupInCorr

RWCox April 01, 2021 11:35AM

Re: Output of 3dGroupInCorr

s.meliss May 11, 2021 05:03AM