Hi,
On 24 Mar 2009, at 19:39, Lara Foland wrote:
> Hello,
>
> I'm using featquery to extract % signal change from each of my
> subjects using
> anatomical ROIs and a cope image. I have two questions:
>
> 1. Some of my subjects are showing a negative percent signal change.
> I am
> concerned that outliers may be causing this (atleast in part). Is
> there any
> easy way to check whether this may be the case?
Do you mean outlier values within the ROI or outlier subjects? If you
mean the former then you could just use alternative measures from the
Featquery output results table, such as median.
>
> 2. If I apply a threshold of "0", does this mean that, foreach
> timepoint where
> % signal change is calculated to be negative, the % signal change is
> set
> to "0"?
I think so, yes.
Cheers.
>
> many thanks in advance for the help!
> Lara
>
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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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