[FieldTrip] impact of skewed power distributions on data analysis

Giuseppe Pellizzer pelli001 at umn.edu
Wed Dec 14 14:44:26 CET 2016

You are definitely correct, the distribution of power is highly skewed.
However, using the log-transform does a pretty decent job at 'normalizing'
the distribution.
A related issue is that when comparing power during a task with baseline,
the ratio Task Power/Baseline Power is highly asymmetric (because it is
equal to 1 when Task Power=Baseline Power, and it can only go down to 0 on
one side and can go to infinity on the other). For all of those reasons, it
is better to use the log-transform of the ratio of power, that is, log(Task
Power/Baseline Power)=log(Task Power) - Log(Baseline Power) (when using
Log10 the result can be expressed in dB by multiplying it by 10).

Giuseppe Pellizzer
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20161214/5a8ab1d8/attachment-0002.html>

More information about the fieldtrip mailing list