yep,
avwroi input output tmin tsize
avwroi starts counting at 0 and you specify the length in TR
ta
christian
On 26 Feb 2004, at 22:32, Lipton, Michael wrote:
> Regarding avwroi:
>
> It seems that I specify the starting point and the length of the "roi"
> I want to extract, corrct?
>
> Is the counting in volume number or time (based on the TR in the AVW
> header?
>
> If the former, is the first volume 0 or 1?
>
> Thanks again,
>
> Michael
>
> -----Original Message-----
> From: Christian F. Beckmann [mailto:[log in to unmask]]
> Sent: Thursday, February 26, 2004 5:23 PM
> To: [log in to unmask]
> Subject: Re: [FSL] Partial time series
>
>
>
> No, data after the 'stop after' is not ignored but compared to a
> constant. If there is signal in the second half, this will not be
> modelled out and thus end up in the GLM residuals, inflating the
> standard error and lowering your stats. You can model signal during
> the entire length of the experiment using 2 different EVs, the first
> one for the first 2 cycles and a second EV for the second 2 cycles.
> This will, however, not give exactly the same results as when using
> avwroi to truncate the data as there is a possibly different 'quality'
> of fit during the first compared to the second half; but it might be
> good enough
>
> ta
> christian
>
>
>
> On 26 Feb 2004, at 22:04, Michael Lipton wrote:
>
> > I am interested in only analyzing the first half (2 of 4 cycles) of a
> > block design dataset. Wil setting the "stop after" field in stats to
> > the correct time accomplish this? The graphic
> > of my model shows and the FEAT web page states that all values in
> the
> > model are set to
> > zero after the "stop after" time. Does this mean that the data is
> > being compared to a
> > constant zero model or is the data beyond the "stop after" time being
> > ignored?
> >
> > If not this approach, is there a way to have FEAT only look at the
> > first part of my data without actually editing the analyze datasets?
> >
> > Thanks,
> >
> > Michael
> >
> --
> Christian F. Beckmann
> Oxford University Centre for Functional
> Magnetic Resonance Imaging of the Brain,
> John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
> Email: [log in to unmask] - http://www.fmrib.ox.ac.uk/~beckmann/
> Phone: +44(0)1865 222782 Fax: +44(0)1865 222717
>
--
Christian F. Beckmann
Oxford University Centre for Functional
Magnetic Resonance Imaging of the Brain,
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
Email: [log in to unmask] - http://www.fmrib.ox.ac.uk/~beckmann/
Phone: +44(0)1865 222782 Fax: +44(0)1865 222717
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