[FieldTrip] calculating behavioural-power correlation

[Hwee Ling Lee]

Dear Arjen,

Thanks for the prompt reply. I keep getting an error message when I set up
my correlation cluster statistics, and I'm not sure what I could have done
wrong. Here's my script:

cfg = [];
cfg.layout = 'EEG1010.lay';
cfg.neighbours = neighbours;
cfg.channel = 'all';
cfg.latency = 'all';
cfg.avgovertime = 'no';
cfg.avgoverchan = 'no';
cfg.avgoverfreq = 'yes';
cfg.parameter = 'powspctrm';
cfg.method = 'montecarlo';
cfg.statistic = 'ft_statfun_correlationT';
cfg.correctm = 'cluster';
cfg.clusteralpha = 0.05;
cfg.clusterstatistics = 'maxsum';
cfg.minnbchan = 2;
cfg.tail = 0;
cfg.clustertail = 0;
cfg.alpha = 0.025;
cfg.numrandomization = 1000;
cfg.ivar = 1;
cfg.uvar = 1;

% design matrices
clear design;
% change in MMSE score relative to baseline
design(1,:) = [0.095238095 -0.045454545 -0.533333333 0.238095238
-0.157894737 0.117647059];
design(2,:) = 1:6;
cfg.design = design;

% for delta band
cfg.frequency = [2 4];
[c200_delta_stat] = ft_freqstatistics(cfg, sub_LF_c200{:});
[c210_delta_stat] = ft_freqstatistics(cfg, sub_HF_c210{:});

Here's the output from Matlab:

computing statistic over the frequency range [2.000 4.000]
the call to "ft_appendfreq" took 0 seconds
the call to "ft_selectdata" took 0 seconds
using "ft_statistics_montecarlo" for the statistical testing
using "ft_statfun_correlationT" for the single-sample statistics
constructing randomized design
total number of measurements     = 6
total number of variables        = 2
number of independent variables  = 1
number of unit variables         = 1
number of within-cell variables  = 0
number of control variables      = 0
using a permutation resampling approach
repeated measurement in variable 1 over 6 levels
number of repeated measurements in each level is 1 1 1 1 1 1
computing a parametric threshold for clustering
Error using ft_statfun_correlationT (line 90)
Invalid specification of the design array.
Error using ft_statistics_montecarlo (line 254)
could not determine the parametric critical value
for clustering

Error in ft_freqstatistics (line 319)
  [stat, cfg] = statmethod(cfg, dat, cfg.design);

Would you please tell what I have done wrong in this case?

Thanks!

Cheers,
Hweeling


On 17 February 2015 at 10:18, Stolk, A. (Arjen) <a.stolk at donders.ru.nl>
wrote:

>  Hi Hweeling,
>
> Have a look at the help of ft_statfun_correlationT, which might be the
> function you're looking for. This function calculates correlations between
> two variables (e.g. subjects' behaviors and brain activities) and converts
> the resulting correlation coefficients to t-statistics.
>
> Best,
> arjen
>
>  --
> Donders Institute for Brain, Cognition and Behaviour
> Centre for Cognitive Neuroimaging
> Radboud University Nijmegen
>
> Email:  a.stolk at donders.ru.nl
> <https://mail.ru.nl/owa/redir.aspx?C=aE7VYn0S90OKCrgPeLfE1S7ZybNAtNEIa36fR052GideznKNfSHe2KSW6d9DoW6tEIOMlaBdT-s.&URL=mailto%3aa.stolk%40donders.ru.nl>
> Phone:  +31(0)243 68294
> Web:    www.arjenstolk.nl
> <https://mail.ru.nl/owa/redir.aspx?C=aE7VYn0S90OKCrgPeLfE1S7ZybNAtNEIa36fR052GideznKNfSHe2KSW6d9DoW6tEIOMlaBdT-s.&URL=http%3a%2f%2fwww.arjenstolk.nl>
>   ------------------------------
> *From:* fieldtrip-bounces at science.ru.nl [fieldtrip-bounces at science.ru.nl]
> on behalf of Hwee Ling Lee [hweeling.lee at gmail.com]
> *Sent:* Tuesday, February 17, 2015 10:06 AM
> *To:* FieldTrip discussion list
> *Subject:* [FieldTrip] calculating behavioural-power correlation
>
>
> Dear all,
>
>  I read on the "walkthrough" that it is possible to calculate
> behavioural-power correlation across subjects. However, I was not sure what
> type of descriptive statistics (i.e. cfg.statistics) I should use when
> performing correlation cluster statistics.
>
>  Would someone please enlighten me which type of statistics I should
> input for cfg.statistics?
>
>  Thanks!
>
>  Best regards,
> Hweeling
>
>
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