[FieldTrip] Behavior-power correlations

[Kaitlyn Litcofsky]

Hello,

I'm trying to conduct behavior-power correlations. This topic has been
discussed a few times before (
http://mailman.science.ru.nl/pipermail/fieldtrip/2015-February/008953.html
and
http://mailman.science.ru.nl/pipermail/fieldtrip/2015-October/009720.html),
but I'm still having issues getting it to work. I'm working with a grand
averaged structure of 25 individuals' frequency data, and trying to
correlate it with a proficiency measurement (one value per person).

If I follow the instructions on the tutorial (
http://www.fieldtriptoolbox.org/faq/how_can_i_test_for_correlations_between_neuronal_data_and_quantitative_stimulus_and_behavioural_variables),
I get an error that "uvar must be specified for dependent samples
statistics". I tried various permutations of the design including a uvar
got the error "Invalid specification of the design array."  When I tried a
suggestion in the previous email threads to ​create a dummy variable that
is a copy of my frequency data, and replace the power spectrum with the
behavioral measure, and create a design with their code:

cfg.design = [];

cfg.design(1,:) = [ones(1,length(BehVar)) 2*ones(1,length(BehVar))];

cfg.design(2,:) = [1:length(BehVar) 1:length(BehVar)];


I get the error "the length of the design matrix (2) does not match the
number of observations in the data (25)".


My question is this: what is the appropriate design array for computing a
correlation with ft_statfun_correlationT? Is the behavioral variable
supposed to be part of the design or must it be part of a dummy structure
designed to be similar in size and structure to the frequency data?


Alternatively, is there a way to get, for every individual in the grand
average, one value representing the average power for, e.g., 300-600ms in
the 4-7Hz range?


Thank you very much for your help,

Kaitlyn Litcofsky


-- 
Kaitlyn Litcofsky
Graduate Student, Cognitive Psychology
006 Moore Building
Pennsylvania State University
University Park, PA 16802
Email: kal378 at psu.edu
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