[FieldTrip] Subject: Re: Is dB baseline normalization following ft_freqanalysis appropriate?

Eelke Spaak e.spaak at donders.ru.nl
Tue Sep 25 09:39:06 CEST 2018

Dear Paul,

> 3. I believe the mistake is related to calling for the baseline
> normalization a second time (cfg.baseline = [-0.4 -0.1] and
> cfg.baselinetype = 'db'). Once removing these configurations, I was able to
> use singleplotTFR fine. Would this produce the errors reported earlier?

Yes. log(x) when x<0 will yield complex results. So don't do dB baseline
more than once.

> Finally, if the error was related to the aforementioned seconding calling
> of baseline normalization, and assuming removing it is the correct
> solution, is it best to perform a baseline normalization following
> ft_freqanalysis if the goal is to eventually move onto group-differences
> using the permutation method?

This depends on the exact details of your experiment. In general, if you're
indeed testing differences between participants, you will indeed want to
apply some form of correction for overall power differences due to distance
to the sensors etc.


> Thank you again for your help.
> Paul
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> https://doi.org/10.1371/journal.pcbi.1002202
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