[FieldTrip] PLV analysis clarification

[Matt Mollison]

Hi Marco,

Could it be that you didn't define cfg.channel, cfg.latency, and
cfg.frequency? (and cfg.avgoverfreq—unless, is there a way to run a cluster
analysis across multiple frequencies?) It seems to me that for a cluster
analysis on plv data you need to rename the 'plvspctrm' field to 'cohspctrm'
and define cfg.channel with the format {'channel - cohrefchannel'} (should
be how it was input in the original ft_freqanalysis function).

Hope that helps.
Matt

On Fri, Mar 25, 2011 at 10:09 AM, BrainBalance Solutions <info at bbss.it>wrote:

> Hi there,
> I'm trying to perform the same analysis and the trick Jan give to tranform
> the pvlspctrm to powerspctrm and labels give me the ability to compute the
> grandaverage.
> But now I'm trying to do a cluster analysis and if I give this simple
> script:
>
> load GApun;
> load GArew;
>
> cfg = [];
> cfg.method           = 'montecarlo';
> cfg.statistic        = 'depsamplesT';
> cfg.correctm         = 'cluster';
> cfg.clusteralpha     = 0.05;
> cfg.clusterstatistic = 'maxsum';
> cfg.minnbchan        = 2;
> cfg.tail             = 0;
> cfg.clustertail      = 0;
> cfg.alpha            = 0.025;
> cfg.numrandomization = 500;
>
> subj = 40;
> design = zeros(2,2*subj);
> for i = 1:subj
>   design(1,i) = i;
> end
> for i = 1:subj
>   design(1,subj+i) = i;
> end
> design(2,1:subj)        = 1;
> design(2,subj+1:2*subj) = 2;
>
> cfg.design   = design;
> cfg.uvar     = 1;
> cfg.ivar     = 2;
>
> [stat] = ft_freqstatistics(cfg, GApun, GArew);
>
>
>
> I have this error:
> ??? Undefined function or variable "sens".
>
> Error in ==> ft_neighbourselection at 95
> if ~isstruct(sens)
>
> Error in ==> statistics_wrapper at 241
>     cfg.neighbours = ft_neighbourselection(cfg,varargin{1});
>
> Error in ==> ft_freqstatistics at 127
> [stat, cfg] = statistics_wrapper(cfg, varargin{:});
>
> Error in ==> calcoloStudent at 31
> [stat] = ft_freqstatistics(cfg, GApun, GArew);
>
>
>
> Following the errors I've found that the problem is in:
> cfg.correctm         = 'cluster';
>
> If I comment it some analysis are done, but I think that clusters are
> skipped (here are some comments):
>
> Warning: The field cfg.clusterstatistic is unused, it will be removed from
> your
> configuration
> The field cfg.clusteralpha is unused, it will be removed from your
> configuration
> The field cfg.clustertail is unused, it will be removed from your
> configuration
>
> and at the end of randomization:
> not performing a correction for multiple comparisons
>
>
> Any idea?
>
> Marco
>
>
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