Statistical comparisons in virtual electrode spectrograms

Jan Mathijs Schoffelen Jan.Schoffelen at FCDONDERS.RU.NL
Fri Nov 10 22:06:51 CET 2006


Dear Piers,

As a matter of fact, I have very little hands on experience with the
clusterrandanalysis myself, and to be honest I'd prefer to use the new
implementation of the statistics-routine, which has the same functionality
as the clusterrandanalysis-function, and which was the subject of the last
activity on this mailing-list, as well as a thread I pointed you to lately.
In any way it is nice to hear that there is progress, and I forward your
questions to the mailing list, so that people more experienced in
clusterrandanalysis can join the discussion and vent their insights.

Yours,

Jan-Mathijs

-----Original Message-----
From: Piers Cornelissen [mailto:p.cornelissen at psych.york.ac.uk]
Sent: Friday, November 10, 2006 3:34 PM
To: Jan Mathijs Schoffelen
Subject: Re: [FIELDTRIP] Statistical comparisons in virtual electrode
spectrograms

Dear Jan

I think I may finally have got somewhere!

However, I would be grateful if you or one of the Fieldtrip team could
look at the clusrand_test.m script, in which I have tried to compare
equal sized baseline with active windows for the group average
spectrogram for one virtual electrode.

As you can see, I have tried to 'borrow'  back a .grad field, which the
freqgrandaverage threw away, and then tried to cheat the neighbood
problem in clsterrandanalysis by setting minnbchan to zero.

At least these manipulations allow clusterrandanalysis to run on the
virtual electrode data, and the attached powerpoint file illustrates
some plots of what I get.

Therefore, the first question is - are these manipulations legitimate,
or have I just generated garbage?

Secondly, if the output is not garbage, then I would appreciate some
pointers at to what the numbers in the fields that I have *ed below
actually represent, please

 >> clusrand

clusrand =

                  stats: [196x51 double]  *
              raweffect: [196x51 double]  *
            posclusters: [1x3 struct]  *
            negclusters: [1x2 struct]  *
    posclusterslabelmat: [1x196x51 double]  *
    negclusterslabelmat: [1x196x51 double]  *
               critvals: [-785.1538 785.1538]  presumably interpretable
when I understand the previous numbers ?*
                  label: {'V0'}
                   freq: [1x196 double]
                   time: [1x51 double]
                    cfg: [1x1 struct]

As ever, I deeply appreciate your and the teams support (it is genuinely
extraordinary!)

Best

Piers



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