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help > RE: number setting ,analyses type,and results
Jan 12, 2012 04:01 AM | Alfonso Nieto-Castanon - Boston University
RE: number setting ,analyses type,and results
Dear Yan,
Regarding (1), if you have three groups and want to test invariance between the groups (e.g. find those areas where the connectivity with a seed area differs between some or all of the three groups) you can do so by selecting all three groups in the 'Between-subjects effects' list, and then entering a contrast of the form [1,-1,0; 0,1,-1] in the 'Between-subjects contrast' field. If instead you simply want to look pairwise at the differences between each pair of groups, then you can simply select a pair of groups in the 'Between-subjects effects' list, and then enter a contrast of the form [1,-1] in the 'Between-subjects contrast' field (and repeat this for each pair of groups).
Regarding (2), yes, all of the analyses ('ROI-to-ROI' 'Seed-to-Voxel' and 'Voxel-to-Voxel') can be performed simultaneously. In the 'Setup->Options' tab simply check all of these analysis types. Then rerun the processing steps (press 'Done' in the Setup, and then Preprocessing tabs), selecting 'No' to the 'overwrite existing subject results' question to avoid repeating the analyses that you have already performed. That should open up all of these analysis types in the 'Analysis' tab, where you can further select specific options for each of these analyses (e.g. select seeds for seed-to-voxel analyses, or groups of ROIs for ROI-to-ROI analyses, etc.)
Regarding (3), in the 'ROI-to-ROI' second-level results display, red and blue circles represent 'target' areas that show positive and negative, respectively, effects above the threshold chosen. The particular meaning of 'effects' here depends on the type of second-level analysis performed. If you are selecting one 'condition' and one 'source' area, and comparing two groups entering a [1,-1] contrast in the 'Between-subjects contrast' field, then 'positive' means that the first group shows higher connectivity than the second group between the selected 'source' area and the displayed 'target' area (and 'negative' means that the second group shows higher connectivity than the first). Hope this helps
Best regards
Alfonso
Originally posted by yan hongjie:
Regarding (1), if you have three groups and want to test invariance between the groups (e.g. find those areas where the connectivity with a seed area differs between some or all of the three groups) you can do so by selecting all three groups in the 'Between-subjects effects' list, and then entering a contrast of the form [1,-1,0; 0,1,-1] in the 'Between-subjects contrast' field. If instead you simply want to look pairwise at the differences between each pair of groups, then you can simply select a pair of groups in the 'Between-subjects effects' list, and then enter a contrast of the form [1,-1] in the 'Between-subjects contrast' field (and repeat this for each pair of groups).
Regarding (2), yes, all of the analyses ('ROI-to-ROI' 'Seed-to-Voxel' and 'Voxel-to-Voxel') can be performed simultaneously. In the 'Setup->Options' tab simply check all of these analysis types. Then rerun the processing steps (press 'Done' in the Setup, and then Preprocessing tabs), selecting 'No' to the 'overwrite existing subject results' question to avoid repeating the analyses that you have already performed. That should open up all of these analysis types in the 'Analysis' tab, where you can further select specific options for each of these analyses (e.g. select seeds for seed-to-voxel analyses, or groups of ROIs for ROI-to-ROI analyses, etc.)
Regarding (3), in the 'ROI-to-ROI' second-level results display, red and blue circles represent 'target' areas that show positive and negative, respectively, effects above the threshold chosen. The particular meaning of 'effects' here depends on the type of second-level analysis performed. If you are selecting one 'condition' and one 'source' area, and comparing two groups entering a [1,-1] contrast in the 'Between-subjects contrast' field, then 'positive' means that the first group shows higher connectivity than the second group between the selected 'source' area and the displayed 'target' area (and 'negative' means that the second group shows higher connectivity than the first). Hope this helps
Best regards
Alfonso
Originally posted by yan hongjie:
Dear export,
good afternoon!
i have some problems on conn.
1. During the part of second-level results , there is a blank called Between-subjects contrast , on the menu there is only example of two groups comparison , now i have 3 groups or even more than 3, which numbers i should type inside the blanks? i want to compare each two of them .especially inside patients groups.
good afternoon!
i have some problems on conn.
1. During the part of second-level results , there is a blank called Between-subjects contrast , on the menu there is only example of two groups comparison , now i have 3 groups or even more than 3, which numbers i should type inside the blanks? i want to compare each two of them .especially inside patients groups.
2.On the left side of the window ,there are 3
kinds of analyses types. yesterday i tried seed-to-voxel but can
not run ROI-to ROI the same time after i did run that.And when
clicked voxel-to-voxel button , there is an error window appeared
saying:"Data not prepared for results.Pree "done"in the analyses
window". i did as it said.but no difference.so , are these 3
analysing types can not be used at the same time?
3.About the analysis results.
The images on the right side of the window, i can not understand clearly. i got one black circle , one white circle with small red point inside,and another 2 red points together.i do not know which is patient's and which is healthy group's.Can you give me some suggestions to understand the results?
Thank you very much .
Best wishes and waiting for your reply .
The images on the right side of the window, i can not understand clearly. i got one black circle , one white circle with small red point inside,and another 2 red points together.i do not know which is patient's and which is healthy group's.Can you give me some suggestions to understand the results?
Thank you very much .
Best wishes and waiting for your reply .
Threaded View
| Title | Author | Date |
|---|---|---|
| yan hongjie | Dec 16, 2011 | |
| Alfonso Nieto-Castanon | Jan 12, 2012 | |