[FieldTrip] Question regarding calculation of effect sizes for cluster-based permutation tests

[Paul Dhami]

Dear Fieldtrip community,

According to this thread (
https://mailman.science.ru.nl/pipermail/fieldtrip/2017-September/011773.html),
Dr. Eric Maris provides a 3 step way to calculate the effect size for
cluster-based permutation tests.

  1.  Calculate the non-standardised effect sizes by averaging the
(sensor, frequency, time)-specific effects within the cluster of
interest. Typically, the (sensor, frequency, time)-specific effects
are raw differences between the subject averages for the experimental
conditions that are being compared.
  2.  Calculate the standard deviation over the subjects of these
non-standardised effect sizes.
  3.  Calculate Cohen’s d by dividing the grand average of the
non-standardised effect sizes by the standard deviation obtained in 2.

However, a few other threads have people suggesting it is not possible
or not recommended. Can anyone else provide guidance as to whether the
method describe above is accurate for getting the effect sizes of
cluster-based permutation tests?

Thank you,

Paul
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