The window length is divided by the number of FIR impulses that you
ask for so that each impulse has duration length/number seconds.
A common approach is to organise that so that the length covers the
normal haemodynamic rise and fall time (eg 15 seconds) and set the
number so that each is one TR in duration.
Cheers.
On 4 May 2007, at 23:16, Junghee Lee wrote:
> Hello Everyone,
> I have a question of using FIR basis function. We used a fast
> event-related design (TR=2) and there are 4 EVs. I would like to
> compare a window of 12 seconds and a window of 14 seconds.
>
> I'm not sure whether I understand what "number" means exactly. Is
> this number of FIR basis functions? If so, is there any optimal
> number of functions I should use?
>
> Thanks a lot!
> Junghee
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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
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