litvak at TECHUNIX.TECHNION.AC.IL
Thu May 11 19:38:24 CEST 2006
clusrand.posclusters and clusrand.negclusters contain all the clusters
found, not just the significant ones.
From: FieldTrip discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL] On Behalf
Of Olga Sysoeva
Sent: Thursday, May 11, 2006 6:30 PM
To: FIELDTRIP at NIC.SURFNET.NL
Subject: [FIELDTRIP] clusterrandomization
Thank you very much for the help.
I continue my succes with Clasterrandomization analysis on within-subject
I applied clasterrandomization to compare two condition. I mostly use the
from the tutorial (both cfg.alphathres =0.05 and cfg.alpha=0.05) and got
positive and negative clusters
(both clusrand.posclusters and clusrand.negclusters not empty). But when I
look for the pval for neg cluster
(which is only one, size 8) it appeared to be 0.51. It is bigger than our
threshold (0.05). Why it is mark as
significant cluster than (clusrand.negclusterlabelmat =1 for 8 elements)?
Could somebody comment on it?
----- Original Message -----
From: "Robert Oostenveld" <r.oostenveld at FCDONDERS.RU.NL>
To: <FIELDTRIP at NIC.SURFNET.NL>
Sent: Monday, May 08, 2006 11:16 AM
Subject: Re: [FIELDTRIP] first success!!!
>> I want to share my first success in using Filedtrip. Although I could
>> still not properly load my current 64 electrodes data, I succeeded in
>> importing my old 19 channel data. Moreover, I succeded in conducting the
>> between-trial clasterrandomization analysis!
> It might be that the automatic projection of the 3D electrodes to the 2D
> surface for plotting is not optimal for your 64 channel set, perhaps due
> to a few very low electrodes. I suggest that you construct a layout file,
> see my previous mail. You can also look into the code in
> private/createlayout, where at the bottom you will find some code that
> helps you to visualise the layout.
>> But I still have problems with within-subject cluster- randomization. The
>> error "did not find the gradiometer or electrode information" appears,
>> line 461. What could it be?
> Cluster randomization requires that the neighbourhood geomerty in the
> data is known, i.e. the neighbouring electrodes. You can specify them
> with cfg.neighbours. It is documented in "help clusterrandanalysis". One
> method to automatically specify the neighbourhood is by having electrode
> information in the dataset, i.e. an elec structure and to specify the
> cfg.neighbourdist option (default is 4 cm, which is suitable for the CTF
> gradiometers). I do not know the units of your electrodes (could be m,
> cm, mm, or unit-scaled dimensionless), but the cfg.neighbourdist should
> be specified in the same units.
> best regards,
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