Hi Alfonso and CONN team,

I have run MVPA analyses and observed significant results. However, the cluster sizes are small and I wonder whether this is an issue? Details of my study are as follows:

4 groups: 

• participant with neurodevelopmental disorder (n=38)


• control group (n=37)


• participant with neurodevelopmental disorder + condition (n=33)


• control group + condition (n=17)

Analyses:

• MVPA analyses (10 factors, 64 components)


• results are more fragmented plus very small clusters (k<10) for 9 and 10 factors


• Analyses run to look at:


• 1. Effect of group on connectivity controlling for covariates + condition. 7 MVPA factors were deemed suitable


• 2. Effect of condition on connectivity controlling for covariates + group. 6 MVPA factors were deemed suitable


• 3. Interaction effect of group x condition on connectivity controlling for covariates. 6 MVPA factors were deemed suitable

Results:

For each set of analyses run, significant clusters surviving FWE were observed. Cluster sizes ranged between 16-34. When non-parametric analyses were run, no significant results were observed. Can you advise whether small cluster sizes are an issue? Is there an expected cluster size? Are such results publishable? The MVPA factors differ for the various tests. Is this allowed, or should they be kept consistent across all tests? What can I do to improve? 

Thanks.