Print

Print
Dear Jun,

You have misread that legend. It's not the case that the window of interest was determined based on an uncorrected statistical test. Panel (b) shows a TF image thresholded at p<0.01 uncorrected for illustrative purposes and panel (c) shows the results of corrected statistical test restricted to a window determined a-priori i.e. not based on the uncorrected test results. 

Restricting the window of interest based on the same data is a common mistake and leads to false positives. You might be interested in looking at the new guidelines paper in Neuroimage http://www.ncbi.nlm.nih.gov/pubmed/23046981 where these issues are discussed in the 'Statistics' chapter.

You can restrict the window of interest using  a mask or 'small volume' button.  When doing a cluster level correction you can note the size of the smallest significant cluster and the largest non-significant cluster and then display the results again using some number in between as the extent threshold. Then only significant clusters will be displayed.

Best,

Vladimir


On Mon, Nov 19, 2012 at 6:12 PM, Jun Wang <[log in to unmask]> wrote:
Dear Vladimir,
   I am reading your paper "EEG and MEG Data Analysis in SPM8". in the figure 3, you mentioned doing TF test based on P<0.01 uncorrected first,then doing statistical test restricted to the window of interest from previous test using FWER p=0.05. is it the usual way to do that, can I do FWER directly. Also how to set restrict window of interest in TF analysis. Last question, How can I plot the signification TF cluster like Figure 3(c), the exported threshold image doesn't look like that.

thanks
Jun