[pymvpa] How to set the chunks with the independent samples?

[Zhen Zonglei]

Hi Michael

Thanks very much. If we set he chunks to a unique value per subject. Then
all chunk-wise preprocessing of the raw data (e.g. zscore) will be improper.
We thus need to preprocess the data out of the whole ChainMapper. Am I
right?



Thanks again.



Zonglei Zhen


On Thu, May 26, 2011 at 6:46 PM, Michael Hanke <michael.hanke at gmail.com>wrote:

>  On Thu, May 26, 2011 at 02:31:21PM +0800, Zhen Zonglei wrote:
> >     We want to train a classifier to decode the state of subject (Patient
> > vs. Normal) from a neuroimaging parameter map and evaluate the accuracy.
> The
> > samples are independent and no clear group of the subjects exists. How
> > should we set the chunk in pymvpa?
> >
> >
> >
> > Another similar question: If we try to predict a mental score from the
> > neuroimaging parameter map for each subject with regression analysis,
> again,
> > how should we set the chunks?
>
> Independent of what you want to do with the data, the chunks indicate
> mutually independent portions of data. If you suspect that there are no
> dependencies between you subjects, you should set the chunks to a unique
> value per subject. I.e.
>
>  chunks = np.arange(len(dataset))
>
>
> Michael
>
> --
> Michael Hanke
> http://mih.voxindeserto.de
>
> _______________________________________________
> Pkg-ExpPsy-PyMVPA mailing list
> Pkg-ExpPsy-PyMVPA at lists.alioth.debian.org
> http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/pkg-exppsy-pymvpa
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.alioth.debian.org/pipermail/pkg-exppsy-pymvpa/attachments/20110526/a420fb6a/attachment-0001.html>