clusterstats empty cfg.neighbours, cfg.neighbours example

[Robert Oostenveld]

Hi Chetan,

Sorry about that, the bookeeping of the data dimensions is a bit
messy, as reflected in the cfg.dim which is pre and post appended all
the time.

On 4 Mar 2010, at 16:51, Chetan Sharma wrote:
> I am still running into bugs when doing the freq_time clustering. I
> am testing for coherence between the hemispheres during a task, and
> now it runs into problems at clusterstat() at line 175.

what is your statfun?

Channel clustering is not supported for all possible statistics, and
especially has limits in the case of bivariate measures such as
coherence.


> The command is:
>
> posclusobs = findcluster(reshape(postailobs,
>       [cfg.dim,1]),channeighbstructmat,cfg.minnbchan);
>
> The problem is that postailobs has size [nfreq*ntime, 1], while the
> cfg.dim is [nchan nfreq ntime], where nchan=2 in this case. It seems
> like it wants to reshape it into size [nfreq, ntime, 1]. Is this
> indeed the case?
>
> And could someone help me out by explaining a bit more about when
> one would choose for cfg.clusterthreshold the different values,
> 'nonparametric_common', 'nonparametric_individual', and 'parametric'
> when testing for coherence in different brain areas? I have read
> over the documentation and the code but am still somewhat unsure.


parametric uses the known parametric distribution of the statistic,
this has to be supported by the statfun.
nonparametric_common estimates a threshold from the randomization
distribution. The threshold is common to all channe-time-frequency
points.
nonparametric_individual estimates an individual threshold from the
randomization distribution for each channe-time-frequency point.

best regards,
Robert

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