Dear SPMers
We would need your help to clarify a remark we received from a reviewer.
Sorry if it is a really basic question:
We performed a two sample T-test between two groups of patients who
underwent a perfusion SPECT study. We applied a uncorrected statistical
threshold p<0.001 and took into account a corrected p value < 0.05 at
cluster level.
We obtained clusters of significant differences in posterior cingulum and
parietal inferior lobule.
Since this is a methodological investigation, the referee argued that:
‘… thresholded maps are not very informative and suggested that results
should also be presented in terms of z-scores (T-scores) averaged on the
unthresholded contrast image for regions of interest that are typically
involved in this disease (disallow the F and T thresholds in SPM for
this). Furthermore the z-scores image should be also presented un-
thresholded (to create them, again disallow statistical threshold in SPM).’
I undestood the reviewer wanted to see the comparison without any
statistical threshold and that may be is permitted by disallowing a
specific SPM function but I was unable to find how to ‘disallow’ F and T
thresholds in SPM.
Can you help me?
thanks in advance for your suggestions
silvia morbelli
Nuclear Medicine Department
San Martino Hospital
Genoa
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