Eric Maris maris at NICI.RU.NL
Mon Oct 2 21:28:03 CEST 2006

Hi Peter,

I'm trying to do clusterrandanalysis on TFR data with the cfg.
statistic='actvsblT' option. The tutorial 'Cluster-level randomization
tests' gives an example in which separate TFRs are calculated for activation
and baseline data. The clusterrandanalysis.m documentation also states that
two datasets must be passed.

However, I'd like to make the activation vs baseline comparison work for
baseline and activation TF windows identified in single TFRs that include a
prestimulus and a poststimulus period. To do so, I used cfg. latency, cfg.
frequency and cfg. keepindividual with freqgrandaverage to create separate
datastructures for the baseline and activation timefrequency windows of

This I don't understand. In my terminology, "baseline" and "prestimulus" are
synonymous, as are "activation" and "poststimulus". The
activation-versus-baseline statistic identifies samples (i.e.,
(sensor,frequency,time)-elements) in the activation/poststimulus period that
are different from the time-average of the corresponding samples in the
baseline/prestimulus period. If you use freqgrandaverage to create an
activation and a baseline datastructure of the same size (with a positive
time-axis for the activation period, and a negative time-axis for the
baseline period), then clusterrandanalysis should do the job.


Eric Maris

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