help > RE: Average within / between network connectivity
Feb 15, 2018  07:02 PM | Helene Veenstra
RE: Average within / between network connectivity
Dear Alfonso,

thank you, this is very helpful information and a welcome suggestion for the first question so that I can present my results a bit more reviewer-friendly. I enjoy the use of CONN and am grateful for the quick feedback on the forum.

Helene
Originally posted by Alfonso Nieto-Castanon:
Dear Helene,

Regarding (1) yes, you are exactly right that a Bonferroni correction of 6 (3 within-/between- network comparisons and 2-tailed) would suffice for these analyses (that is the number of multiple tests that are being evaluated by that script). If you prefer, you could also (perhaps a bit more standard) first convert the three uncorrected p-values output by the script into two-sided p-values (using a p2 = 2*min(p,1-p) formula), and then apply FDR across those multiple tests (using a P = conn_fdr(p2) command). That should be similarly valid and a bit less conservative than Bonferroni. 

Regarding (2), the former computation is used (i.e. the script averages the ROI-to-ROI connectivity values between all ROI pairs with ROI1 in set1 and ROI2 in set2)

Hope this helps, and my apologies that this conn_withinbetween* script/functionality is still undocumented, I will eventually get around to making this part of the standard set of ROI/network analyses in CONN

Alfonso
Originally posted by Helene Veenstra:
Dear Alfonso,

Reviving an older thread as I am using this code line for my analyses, as I was interested in network connectivity changes related to covariates and groups. I have a couple of questions. 

1) since this analysis uses (uncorrected) two-tailed p-values; however draws from a small pool of regions to test, would it be appropriate to consider the results being adequately corrected with a Bonferroni correction for number of tests, and appropriate choice of number of tails?

Example: I investigate several hypotheses (different covariates/group comparisons) for the connectivity within two networks (SN, DMN) and the connectivity between those two. To obtain a p-value <0.05 per hypothesis, I use a corrected p-value with a Bonferroni correction of 6 (p<0.0083) based on 3 network (SN, DMN, SN-DMN) tests * 2 for two-tailed. 

2) as you explained this gives an average over all ROI connections within each chosen network. But how exactly is the between-network value calculated? As an average of every possible ROI (group1) to ROI (group2) connection? Or a calculated connectivity of the averaged connectivity over all ROIs within each group?

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RE: Average within / between network connectivity
Helene Veenstra Feb 15, 2018
Stephen L. Feb 8, 2018
Helene Veenstra Feb 12, 2018
Mariah DeSerisy Apr 30, 2020
Elizabeth Olson May 16, 2020
Alfonso Nieto-Castanon May 19, 2020
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