[pymvpa] Train and test on different classes from a dataset

Francisco Pereira francisco.pereira at gmail.com
Tue Feb 5 13:33:39 UTC 2013

I'm catching up with this long thread and all I can say is I fully
concur with Michael, in particular:

On Tue, Feb 5, 2013 at 3:11 AM, Michael Hanke <mih at debian.org> wrote:
> Why are we doing permutation analysis? Because we want to know how
> likely it is to observe a specific prediction performance on a
> particular dataset under the H0 hypothesis, i.e. how good can a
> classifier get at predicting our empirical data when the training
> did not contain the signal of interest -- aka chance performance.

Permuting the test set might make sense, perhaps, if you wanted to
make a statement about the result variability over all possible test
sets of that size if H0 was true.


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