open-discussion
open-discussion > RE: Comparison group in the second-level
Sep 11, 2015 05:09 PM | Alfonso Nieto-Castanon - Boston University
RE: Comparison group in the second-level
Dear Maud,
The standard ROI-to-ROI analysis test across groups (e.g. selecting both groups and entering a [1 -1] contrast) will look for differences in "strength" of connectivity between groups (e.g. comparing the average Fisher-transformed correlation coefficients across the two groups), rather than testing about the difference in "presence/absence" of connectivity between the two groups. If you want to do something like the latter instead, you may want to select 'graph-theory' analyses (in the ROI-to-ROI results tab) and then look at the degree or cost measures for each ROI. Those measures will test for differences between the groups in the "number" of connections of each ROI (where the presence/absence of a connection is defined by your network-forming correlation threshold)
Hope this helps
Alfonso
Originally posted by Maud Dupuy:
The standard ROI-to-ROI analysis test across groups (e.g. selecting both groups and entering a [1 -1] contrast) will look for differences in "strength" of connectivity between groups (e.g. comparing the average Fisher-transformed correlation coefficients across the two groups), rather than testing about the difference in "presence/absence" of connectivity between the two groups. If you want to do something like the latter instead, you may want to select 'graph-theory' analyses (in the ROI-to-ROI results tab) and then look at the degree or cost measures for each ROI. Those measures will test for differences between the groups in the "number" of connections of each ROI (where the presence/absence of a connection is defined by your network-forming correlation threshold)
Hope this helps
Alfonso
Originally posted by Maud Dupuy:
Dear conn users, Dear Alfonso,
when performing a functional connectivity (ROI-to-ROI) comparison group in the second-level analysis (for example to compare the connectivity results of patients vs. controls), does the conn tool box take into account an absence of connectivity in this analysis?
For example, is it possible that it shows a result for the group patient connectivity = 0 vs. of the group control connectivity = 0.5?
Or, is that the conn tool box only shows the between-groups differences in connectivity for existing connection in both groups (but that differ in terms of strength, not in terms of presence vs. absence)?
Thank you for your attention to these matters.
when performing a functional connectivity (ROI-to-ROI) comparison group in the second-level analysis (for example to compare the connectivity results of patients vs. controls), does the conn tool box take into account an absence of connectivity in this analysis?
For example, is it possible that it shows a result for the group patient connectivity = 0 vs. of the group control connectivity = 0.5?
Or, is that the conn tool box only shows the between-groups differences in connectivity for existing connection in both groups (but that differ in terms of strength, not in terms of presence vs. absence)?
Thank you for your attention to these matters.
Threaded View
| Title | Author | Date |
|---|---|---|
| Maud Dupuy | Sep 7, 2015 | |
| ladan shahshahani | Oct 23, 2015 | |
| Alfonso Nieto-Castanon | Sep 11, 2015 | |