[FieldTrip] File Size depends on No. of Trials?

[Blume Christine]

Dear Community,

I have an issue with data size. I am processing high-density EEG data from a sleep study. Following preprocessing I perform time-frequency transformations and a baseline correction using the following code:

        cfg = [];
        cfg.method = 'wavelet';
        cfg.output = 'pow';
        cfg.keeptrials = 'no';
        cfg.width = 3; %
        cfg.foi = 1:1:16; %
        cfg.toi = -0.7:0.2:0.9;
        freqanalysis_FV = ft_freqanalysis(cfg, data_FV);

        cfg = [];
        cfg.baseline = [-0.6, 0];
        cfg.baselinetype = 'relchange';
        ERDERS_FV = ft_freqbaseline(cfg, freqanalysis_FV)

As you can see, I do not keep the trials. Still, the size of ERDERS seems to depend on the size of data_FV. Why is that the case? Also, changing cfg.foi does not change the file size - why? The problem is that this way the data can hardly be handled as it takes up so much RAM. Please note that I do clear everything from the workspace I do not need, that should not be the issue.

Thanks a lot for your thoughts.

Best,
Christine

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