Hi - no, it's not quite that simple. The default thresholding in FEAT
is cluster-based - so you are just talking about the initial cluster-
forming threhsold.
Please see the FEAT manual for more detail on this, and then the
Cambridge Imagers wiki page for a lot more information about random
field theory and cluster-based thresholding.
Cheers.
On 13 Jun 2009, at 12:50, Nestor, Liam (Contractor) wrote:
> Any takers (see below)?
>
>
> *******************************************
> Liam Nestor, Ph.D
> Office C8-523
> Laboratory for Molecular Neuroimaging
> Semel Institute for Neuroscience and Human Behavior
> 760 Westwood Plaza
> Los Angeles 90024
> Tel: 310-206-0655
> E-mail: [log in to unmask]
> *******************************************
> ________________________________________
> From: FSL - FMRIB's Software Library [[log in to unmask]] On Behalf
> Of Liam Nestor [[log in to unmask]]
> Sent: Wednesday, June 10, 2009 3:05 PM
> To: [log in to unmask]
> Subject: [FSL] Thresholding query
>
> Dear FSL users
>
> I am currently running higher level (between groups unpaired t-tests)
> analyses and I have a query regarding threshold values.
>
> FSL has the Z value threshold set to 2.3 by default. My understand
> is that
> 2.3 is the equivalent to 0.01 one-tailed and 1.96 is the equivalent
> to 0.05
> two-tailed. Is this correct?
>
> Can somebody provide some clarification about what 2.3 and 1.96
> thresholds
> mean, (if I am wrong) as I have used both these values for analyses.
>
> Thanks you.
>
> Liam.
>
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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)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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