[Eeglablist] crossf function option 'alpha' usage
arno delorme
arno at ucsd.edu
Sun Nov 2 09:53:28 PST 2008
Dear Kyongsik,
the coherence values returned are not masked by significance. To mask
them you need to use the 'cohboot' threshold values. There is one
threshold value for each frequency in 'cohboot', so you need to use
repmat to make 'cohboot' the same size as 'coh'
mask = coh > repmat(cohboot, [ 1 size(coh,2) ]); % mask of 0 and 1
figure; imagesc(timesout, freqsout, coh .* mask); % plot
cl = caxis; caxis([-cl(2) cl(2)]); % color axis
Best,
Arno
On 1 nov. 08, at 04:41, Kyongsik Yun wrote:
> I used
> [coh,mcoh,timesout,freqsout,cohboot,cohangles]= pop_newcrossf( eeg,
> 1, i, j, [-2000 1998], [3 0.5] ,'type', 'phasecoher',
> 'topovec', [i j], 'elocs', chanlocs, 'chaninfo', chaninfo, 'alpha',
> 0.01,'padratio', 4);
>
> I obtained 'coherence' color coded time-frequency map. I saw the non-
> significant output values as green in the map.
> As far as I know, this 'coherence' values is in the variable 'coh'.
> However, I cannot find any '0' values in 'coh', while the map shows
> 'green'.
> This is strange.
>
> I want to get statistically significant 'phase coherence' values
> using option 'alpha', but I think I misued the option 'alpha' or
> something.
>
> Thank you.
>
> Kyongsik Yun
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