[FieldTrip] MEG Time-Frequency testing (ft_freqstatistics)

[Eric Maris]

Kambiz,

> >Have a look at the (channel,frequency)-specific paired t-tests.
> I am not sure exactly what you mean. By 'specific' do you mean sample
> wise testing in a narrow frequency range?

Sorry, I forgot that you have time resolution. I mean the
(channel,time,frequency)-specific paired t-tests, which are in the output of
freqstatistics.


Best,

Eric


> 
> -K.
> -------------------------------------------------------------
> Kambiz Tavabi PhD
> Biomedical Imaging Laboratory
> The Children's Hospital of Philadelphia
> 34th Street and Civic Center Boulevard
> Philadelphia, Pa. 19104
> Tel: 267.426.0302
> email: tavabik at email.chop.edu
> -------------------------------------------------------------
> ________________________________________
> From: fieldtrip-bounces at donders.ru.nl [fieldtrip-bounces at donders.ru.nl]
> On Behalf Of Eric Maris [e.maris at donders.ru.nl]
> Sent: Wednesday, December 15, 2010 5:36 PM
> To: 'Email discussion list for the FieldTrip project'
> Subject: Re: [FieldTrip] MEG Time-Frequency testing (ft_freqstatistics)
> 
> Dear Kambiz,
> 
> 
> > Greetings Fieldstrippers
> 
> "Fieldtrippers" may have connotations that a scientist does not always
> appreciate, but what to think of "Fieldstrippers"?
> 
> > My problem with the results in the attachment is that in the grand
> > averages there is an obvious event related desynchrony (cold colors,
> > negative values) difference between 0.4-0.8sec; 10-40hz which somehow
> > doesn't get picked up, but the small blip of noise/event-related
> > synchrony (hot colors, positive values) c. 0.5sec at 50Hz is revealed
> > as different between conditions by the permutations!
> 
> Have a look at the (channel,frequency)-specific paired t-tests. Do
> these
> detect the big cold blob? If not, the variance across subjects is
> probably
> large.
> 
> 
> Best,
> 
> Eric Maris
> 
> 
> 
> 
> 
> 
> To carry out the
> > permutations I used
> > cfg.method           = 'montecarlo';
> > cfg.statistic        = 'depsamplesT';
> > cfg.correctm         = 'cluster';
> > cfg.clusteralpha     = 0.05;
> > cfg.clusterstatistic = 'maxsum';
> > cfg.neighbours       = [ ];
> > cfg.tail             = 0;
> > cfg.clustertail      = 0;
> > cfg.alpha            = 0.05;
> > cfg.numrandomization = 500;
> > So I presume that the result is not due to a signs (pos/neg values)
> > issue, if I am using a two-tailed test. Changing cfg.tail &
> > cfg.clustertail to 1 makes little to no difference, and a value of -1
> > results in errors. Basically, I'd appreciate if someone, based on
> what
> > is observable in the grand averages, could confirm that the
> permutation
> > result makes sense? And if not then some advice on what I am doing
> > wrong. Thank you. -Kambiz
> >
> > -K.
> > ------------------------------------------------------------
> > Kambiz Tavabi PhD
> > Biomedical Imaging Laboratory
> > The Children's Hospital of Philadelphia
> > 34th Street and Civic Center Boulevard
> > Philadelphia, Pa. 19104
> > Tel: 267.426.0302
> > email: tavabik at email.chop.edu<mailto:tavabik at email.chop.edu>
> > ------------------------------------------------------------
> 
> 
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> 
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip