Simply EEGLAB

Precomputing measures

Station 8 · Lesson 5 · EEGLAB 2026.1

In the GUI

StudyPrecompute channel measuresPre-compute channel measures for STUDY 'Go-nogo animal (mine)'
Spherical interpolation of missing channels (performed after optional ICA removal below)
Remove ICA artifactual components pre-tagged in each dataset
Remove artifactual ICA cluster or clusters (hold shift key)
ERPs...Select parameters for ERP
Baseline (min max) ("rmbase")Epoch start (sec)Ok -1000 0
Power spectrum 'specmode', 'fft', 'logtrials', 'off'
ERSPsITCs
Overwrite files on diskYes WARNING: SOME DATAFILES ALREADY EXIST, OVERWRITE THEM?animal.studyanimal_mine.study
Ok

Script

baseline = [round(ALLEEG(1).xmin*1000) 0];   % from the epoch start to 0 ms
[STUDY, ALLEEG] = std_precomp(STUDY, ALLEEG, {}, 'savetrials', 'on', 'interp', 'on', 'recompute', 'on', ...
    'erp', 'on', 'erpparams', {'rmbase', baseline}, ...
    'spec', 'on', 'specparams', {'specmode', 'fft', 'logtrials', 'off'}, ...
    'ersp', 'on', 'itc', 'on', 'erspparams', {'cycles', [3 0.8], 'freqs', [3 30], 'nfreqs', 20, 'ntimesout', 50});
STUDY = pop_savestudy(STUDY, ALLEEG, 'savemode', 'resave');
first = STUDY.datasetinfo(1);
measureFiles = dir(fullfile(first.filepath, [first.subject '.dat*']));
for k = 1:numel(measureFiles)
    fprintf('%-24s %8.1f MB\n', measureFiles(k).name, measureFiles(k).bytes/1e6);
end
fprintf('Channel groups in the STUDY: %d\n', numel(STUDY.changrp));

Which value should I choose?

Option	In this lesson	General rule
Baseline (`rmbase`)	From the epoch start to 0 ms	The same baseline you used for each participant. If the data are already corrected, a second correction does no harm.
Interpolation (`interp`)	on, as in the window	In the script its default is off, so write it out. It is better to interpolate missing channels in each participant's file before the STUDY, where you can see them.
ICA removal (`rmicacomps`)	off	on only if components are flagged in every file and were not removed from the data before.
Spectrum (`specparams`)	`'specmode', 'fft', 'logtrials', 'off'`	The default suits a first analysis. Change it only for a methodological reason.
ERSP (`erspparams`)	Every channel, 20 frequencies from 3 to 30 Hz, 50 time points	A finer grid only for the frequencies and times in your research question. Keep every channel in EEGLAB 2026.1.
Save trials (`savetrials`)	on	Fixed: current EEGLAB has no other choice, and the window always adds it.
Recompute (`recompute`)	on	on whenever you change any option, otherwise EEGLAB reads the old files.

For your Methods

Channel ERPs and spectra were precomputed for each participant and condition (std_precomp), with baseline correction from [−1000] to 0 ms; with spherical interpolation of any missing channels enabled; event-related spectral perturbations were computed at every channel for [20] frequencies from [3] to [30] Hz.

In the GUI

Script

Which value should I choose?

For your Methods

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