Hi,
the higher-level analysis uses unthresholded lower-level results as
input - not the thresholded versions. That is, your lower-level
threshold levels have no impact on the higher-level results.
hope this helps
christian
On 8 Feb 2007, at 12:35, Benny Liberg wrote:
> Hi,
>
> I am investigating a group of subjects recieving medication known to
> decimate the BOLD contrast. When I set a Z: >2.3 (p=0.05), two
> subjects
> doesn't show any activation in the ROI. However, an uncorrected
> analysis or
> a subtanstially lower Z threshold (>1.4) reveal activation in the ROI.
>
> Is the activity/variance (<2.3 at first-level) accounted for in a
> higher-
> level analysis with a Z: >2.3, p=0.05, or are is any data from
> these "subthreshold subjects" excluded when I look at group effects?
>
> Kind regards,
> Benny Liberg
--
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 222551 Fax: +44(0)1865 222717
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