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help > RE: combining sources
Jun 18, 2014 11:06 PM | Alfonso Nieto-Castanon - Boston University
RE: combining sources
Hi Mary,
The appropriate contrast (the one that you entered in the CONN gui to generate the corresponding second-level results) should always appear in that list named as 'connectivity results'. The reason you are not seeing it there is likely because in your case this is an F-contrast, so you need to click on 'F-contrasts' when the SPM contrast manager shows up and you should find it there.
Just for reference, the SPM design matrix generated by CONN for any arbitrary second-level analysis always has [N1* N2 * N3] total number of columns, where N1 is the number of effects selected in the between-subjects list, N2 is the number of rows in the between-sources contrast defined, and N3 is the number of rows in the between-conditions contrast defined. The interpretation of the different columns in the design matrix follows the same order as above (i.e. the first N1 columns correspond to the subject effects modeled for the first between-conditions contrast and first between-sources contrast, the next N1 columns correspond to the subject effects modeled for the second between-conditions contrast and first between-sources contrast, etc.) In your case, the first two columns correspond to the within-group effects for the first seed/ROI, and the last two columns correspond to the within-group effects for the second seed/ROI, so the appropriate F-contrast to look at between-group differences across any of the two sources should look like: [1 -1 0 0; 0 0 1 -1].
Hope this helps
Alfonso
Originally posted by Mary Newsome:
The appropriate contrast (the one that you entered in the CONN gui to generate the corresponding second-level results) should always appear in that list named as 'connectivity results'. The reason you are not seeing it there is likely because in your case this is an F-contrast, so you need to click on 'F-contrasts' when the SPM contrast manager shows up and you should find it there.
Just for reference, the SPM design matrix generated by CONN for any arbitrary second-level analysis always has [N1* N2 * N3] total number of columns, where N1 is the number of effects selected in the between-subjects list, N2 is the number of rows in the between-sources contrast defined, and N3 is the number of rows in the between-conditions contrast defined. The interpretation of the different columns in the design matrix follows the same order as above (i.e. the first N1 columns correspond to the subject effects modeled for the first between-conditions contrast and first between-sources contrast, the next N1 columns correspond to the subject effects modeled for the second between-conditions contrast and first between-sources contrast, etc.) In your case, the first two columns correspond to the within-group effects for the first seed/ROI, and the last two columns correspond to the within-group effects for the second seed/ROI, so the appropriate F-contrast to look at between-group differences across any of the two sources should look like: [1 -1 0 0; 0 0 1 -1].
Hope this helps
Alfonso
Originally posted by Mary Newsome:
Hi Alfonso,
Thanks very much. This worked, and as I was exploring the clusters, I was prompted to enter contrast weights in a contrast manager, which had 4 columns. I had two groups and two sources selected. Would the first two columns refer to the two groups, and the last two columns refer to the two sources? And if I wanted to compare the patient group to the control group across the two sources, I would enter 1 -1 0 0?
Thanks again,
Mary
Thanks very much. This worked, and as I was exploring the clusters, I was prompted to enter contrast weights in a contrast manager, which had 4 columns. I had two groups and two sources selected. Would the first two columns refer to the two groups, and the last two columns refer to the two sources? And if I wanted to compare the patient group to the control group across the two sources, I would enter 1 -1 0 0?
Thanks again,
Mary
Threaded View
| Title | Author | Date |
|---|---|---|
| Mary Newsome | Jun 12, 2014 | |
| Alfonso Nieto-Castanon | Jun 13, 2014 | |
| Mary Newsome | Jun 16, 2014 | |
| Alfonso Nieto-Castanon | Jun 16, 2014 | |
| Laila Franke | Nov 14, 2019 | |
| Mary Newsome | Jun 17, 2014 | |
| Alfonso Nieto-Castanon | Jun 18, 2014 | |
| Mary Newsome | Jun 18, 2014 | |
| Alfonso Nieto-Castanon | Jun 18, 2014 | |
| Mary Newsome | Jun 19, 2014 | |
| Mary Newsome | Jun 19, 2014 | |
| Alfonso Nieto-Castanon | Jun 20, 2014 | |
| Mary Newsome | Jun 21, 2014 | |