[FieldTrip] Is dB baseline normalization following ft_freqanalysis appropriate?
Paul Dhami
pdhami06 at gmail.com
Sat Sep 22 16:53:04 CEST 2018
Dear Fieldtrip community,
I am ultimately hoping to perform the cluster-based permutation testing for
comparing potential power differences between two groups.
>From my understanding, to facilitate statistical comparisons, baseline
normalization is warranted.
Would it be appropriate (if at all) to do this baseline normalization right
after following ft_freqanalysis?
My current frequency preprocessing looks like this for a single subject:
% frequency analysis
cfg = [];
cfg.output = 'powandcsd';
cfg.method = 'mtmconvol';
cfg.foi = 2:1:40;
cfg.t_ftimwin = 2 ./ cfg.foi;
cfg.tapsmofrq = 0.4 *cfg.foi;
cfg.toi = -0.4:0.01:0.4;
dataSPfreq = ft_freqanalysis(cfg, dataSPfreq);
%baseline correction
cfg = [];
cfg.baseline = [-0.4 -0.1];
cfg.baselinetype = 'db';
dataSPfreq = ft_freqbaseline(cfg, dataSPfreq);
>From here, I then was hoping to submit my two structures, each containing
the single subject preprocessed data from their respective group, to
freq_statistics.
I initially thought this was fine, but when trying to use ft_singleplotTFR,
I ran into this error: Complex values are not supported, which only
occurred when I did the baseline correction (I also ran it without any
baseline correction and it worked fine).
Any insight would be greatly appreciated.
Thank you,
Paul
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