Hi, I am getting consistently better prediction when I don't make haemodynamic lag shift. Have you ever experienced something similar? I would expect the opposite results. I have closely examined the code and there are no bugs there.
Thanks, Vadim 2009/4/29 Yaroslav Halchenko <[email protected]> > there are a few options you have... > > in a block design experiment you can either > 1. discard volumes on the boundaries of the blocks -- look at > idsonboundaries > method of a dataset to figure out which volumes you need to discard > > 2. shift labels to account for the hemodynamic response... lets say > with TR=2 and desired shift of 6 seconds, just shift labels by 3 and > discard first 3 volumes... smth like (just typed in... not tested ;)) > > dataset.labels[3:] = dataset.labels[:-3] > dataset = dataset.selectSamples(range(3, dataset.nsamples)) > > 3. use BoxcarMapper mapper to just get a mean activation pattern of the > block (or simply use that ERNiftiDataset in the fashion similar to > ER-dataset analysis) > > > > On Wed, 29 Apr 2009, Vadim Axel wrote: > > > Hi guys, > > I wonder whether you are making hemodynamic lag shift in pyMVPA? Here > > it the thread, where you discussed this issue with regard to Haxby's > > dataset. > > [1] > http://www.mail-archive.com/[email protected] > > g/msg00173.html > > I think it's a critical procedure, especially when designed consists > of > > short blocks (like 10-15 secs), where you might miss considerable > > amount of information. As far as I remember in Princeton MVPA matlab > > toolbox such a option existed. > > Thaanks, > > Vadim > > > Ссылки > > > 1. > http://www.mail-archive.com/[email protected]/msg00173.html > > > _______________________________________________ > > Pkg-ExpPsy-PyMVPA mailing list > > [email protected] > > http://lists.alioth.debian.org/mailman/listinfo/pkg-exppsy-pymvpa > > > -- > Yaroslav Halchenko > Research Assistant, Psychology Department, Rutgers-Newark > Student Ph.D. @ CS Dept. NJIT > Office: (973) 353-1412 | FWD: 82823 | Fax: (973) 353-1171 > 101 Warren Str, Smith Hall, Rm 4-105, Newark NJ 07102 > WWW: http://www.linkedin.com/in/yarik > > _______________________________________________ > Pkg-ExpPsy-PyMVPA mailing list > [email protected] > http://lists.alioth.debian.org/mailman/listinfo/pkg-exppsy-pymvpa >
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