[FieldTrip] calculating behavioural-power correlation -- follow-up questions

[Arjen Stolk]

Dear participants in the discussion on behavioural-power correlation, and
interested folks,

Following recent discussion on this mailing list (thanks to Xiaoming Du and
Martin Krebber), we have updated ft_statfun_correlationT, a function that
can be used for correlating neural and behavioral variables.

Following the update, the correlation values calculated on genuine data
have not changed. However, the permutation procedure for calculating the
randomization distribution has. Namely, prior to the update the permutation
procedure would randomly permute across both the independent (e.g.,
behavior) and dependent variables (e.g., neural data). This procedure is
prone to systematic bias across the data belonging to these variables. And
conceptually, as outlined in a new wiki page (see below), the independent
and dependent variables should be statistically independent, meaning that
any association between these variables should be broken by randomly
permuting the values of the independent variable.

http://www.fieldtriptoolbox.org/faq/how_can_i_test_for_correlations_between_neuronal_data_and_quantitative_stimulus_and_behavioural_variables
?

Those that have been using ft_statfun_correlationT for calculating a
randomization distribution using the permutation procedure are advised to
update to the latest fieldtrip version and re-calculate those
distributions. We are sorry for any inconvenience this may cause.

On a related note, the functionality of ft_statfun_correlationT (under
Pearson) is highly similar to that of ft_statfun_indepsamplesregrT. To make
the latter function, and others in the statfun suite, more accessible, we
would like to forward those interested to the above wiki page where an
overview is provided of the different approaches to correlating neural and
behavioral variables, with some example fieldtrip code.

Yours, Arjen
on behalf of Eric Maris and Egbert Hartstra

2015-10-22 2:53 GMT-07:00 Maris, E.G.G. (Eric) <e.maris at donders.ru.nl>:

> Dear participants in the discussion on behavioural-power correlation,
>
> My name is Eric Maris and have contributed most of the older statfuns (but
> not ft_statfun_correlationT). Together with Arjen, I will try to resolve
> some of the issues that have been discussed. Give us some time, and we will
> return to you via the Discussion List.
>
> best,
> Eric
>
>
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> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>
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