Stephen,

Thanks for replying.  What I am trying to obtain is a sense of how statistically accurate each measure of volume is.  For example, for patient X, I get a gray matter volume of 600 cc.  What is the 95% confidence interval of this measurement?  I realize there may not be an answer to this question, and may go back to how accurate historically is FAST compared to some accepted gold standard.

Chang

From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf Of Stephen Smith
Sent: Friday, March 15, 2013 10:13 AM
To: [log in to unmask]
Subject: Re: [FSL] confidence intervals for FAST

Hi - sorry, but it's not clear what you're asking for here - in particular it's not clear exactly what you mean by "confidence interval".

Cheers.

On 14 Mar 2013, at 17:48, Ho, Chang Yueh wrote:

Hello,

I am using automated segmentation as described in your educational materials by skull stripping with BET and using FAST to segment white, gray and CSF volumes.  We are doing a feasibility project in autistic children and have a small sample of children with autism and age matched children without.  I understand there is an option for FSLstats to display the 2-98% interval for signal intensity values for a data set but is there any option for the measure of accuracy of the specific volume of the data set obtained by –m –v?  For example a confidence interval of the segmented volume of gray matter?  I believe this would help our statistician with calculations for significance and power.

Thanks for your help.

Chang

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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)  2176
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