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Hi Donald - I know this may seem rather obvious, but could you tell me where in the bottom left of the table is the minimum cluster size that has a cluster corrected p-value less than 0.05? Is this the same thing as the 'extent threshold k = 0 voxels' that I see at the bottom left of the table? I expect this is because I put in 0 under the extent threshold in the results tab.

Also, how can I cluster FDR from the table? And what is FDR? I only see in the results table a FDRp value and FDRc?

I'm attaching a screenshot of my results table for reference.

Thanks and apologize for my extensive questioning :-P
Joelle

On Tue, Aug 11, 2015 at 2:58 PM, MCLAREN, Donald <[log in to unmask]> wrote:
In the results table, the bottom left of the table provides the minimum cluster size that has a cluster corrected p-value less than 0.05. You can then use this cluster size when you display the data and the clusters showing will all be significant with the FWE control. You can also use cluster FDR from the table (SPM) or 3dClustSim (afni) to determine the cluster size to use.

Best Regards, 
Donald McLaren, PhD


On Tue, Aug 11, 2015 at 12:22 PM, Joelle Zimmermann <[log in to unmask]> wrote:
Thanks Donald. How can I control the FWE at the cluster level in the GUI? - where can I find this option?

On Tue, Aug 11, 2015 at 12:14 PM, MCLAREN, Donald <[log in to unmask]> wrote:
If you go with an uncorrected voxel criteria, which I suggest, then you should correct for multiple comparisons by controlling the FWE at the cluster level for publication. If its an intermediate analysis, controlling the cluster-wise alpha is less of an issue.

Best Regards, 
Donald McLaren, PhD


On Tue, Aug 11, 2015 at 12:06 PM, Joelle Zimmermann <[log in to unmask]> wrote:
Hi Donald,

Good to hear from you again. Right, that's what I suspected about the first-level. I have 28 subjects in my dataset, and not seeing all that much at FWE. As long as there isn't a strict standard SPM people go with, I think .001 is better for me.

Later I plan to split my 28 subjects into 2 groups so will have even fewer subjects.

Thanks,
Joelle

On Tue, Aug 11, 2015 at 12:02 PM, MCLAREN, Donald <[log in to unmask]> wrote:
Statistical Thresholding at the first level has no impact on the second-level data.

For the second-level, it depends on how large the effect size you expect to see and how many subjects you have in your dataset. 

Best Regards, 
Donald McLaren, PhD


On Tue, Aug 11, 2015 at 10:58 AM, Joelle Zimmermann <[log in to unmask]> wrote:
Hi Experts,

I'm running a first-level analysis per subject, and then forwarding the .con images into a second-level analysis.

I'm wondering if there is a standard way to set the p-value adjustment to control in the results tab for the first-level and the second-level analysis. For instance, would you recommend FWE for the first-level single subject analyses, and .001 for the second-level analysis?

Thanks,
Joelle