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help > RE: Comparing groups - best practice
Nov 15, 2018 08:11 AM | Yuval Argaman
RE: Comparing groups - best practice
Dear Or,
Assuming this is a simple unpaired test, the correct way to approach this is to define 2 second-level covariates at the setup step: Treatment and Placebo.
In each one, you would assign a 1 for the treatment type corresponding to each subject. For example, assuming the following:
Subejet1 - Treatment
Subject2 - Treatment
Subject3 - Placebo
Subject5 - Treatment
Subject6 - Placebo
The 'treatment' covariate would be defined as [1 1 0 1 0] and the `placebo` covariate as [0 0 1 0 1].
Then, in the 2nd-level analysis (seed-based, voxel-level etc.) you should select both groups in the between-subject column. Then, assign them with the desired contrast (Treatment>Placebo or vice-versa) by typing in [1 -1] or [-1 1].
Hope this helps. Good luck!
Sincerely,
-Yuval.
You can also look it up in the CONN manual,
Originally posted by Or Duek:
Assuming this is a simple unpaired test, the correct way to approach this is to define 2 second-level covariates at the setup step: Treatment and Placebo.
In each one, you would assign a 1 for the treatment type corresponding to each subject. For example, assuming the following:
Subejet1 - Treatment
Subject2 - Treatment
Subject3 - Placebo
Subject5 - Treatment
Subject6 - Placebo
The 'treatment' covariate would be defined as [1 1 0 1 0] and the `placebo` covariate as [0 0 1 0 1].
Then, in the 2nd-level analysis (seed-based, voxel-level etc.) you should select both groups in the between-subject column. Then, assign them with the desired contrast (Treatment>Placebo or vice-versa) by typing in [1 -1] or [-1 1].
Hope this helps. Good luck!
Sincerely,
-Yuval.
You can also look it up in the CONN manual,
Originally posted by Or Duek:
Hi,
I have two groups (treatment, placebo) and I want to compare these group's resting state (per session).
I found two options and was wondering whats the best way:
In setup 1st level analysis:
create a contrast with treatment as 1 and ctrl as 0 (per subject).
create a contrast with treatment as 1 and ctrl as -1 (per subject).
In second level results:
select allSubjects and only treatment (contrasted 1 and 0) and then choose simple effects.
OR
select the subject to subject contrast that was done in the 1st level analysis (1 and -1)
Whats the best practice?
Thank you for the help and the toolbox itself.
Or D.
I have two groups (treatment, placebo) and I want to compare these group's resting state (per session).
I found two options and was wondering whats the best way:
In setup 1st level analysis:
create a contrast with treatment as 1 and ctrl as 0 (per subject).
create a contrast with treatment as 1 and ctrl as -1 (per subject).
In second level results:
select allSubjects and only treatment (contrasted 1 and 0) and then choose simple effects.
OR
select the subject to subject contrast that was done in the 1st level analysis (1 and -1)
Whats the best practice?
Thank you for the help and the toolbox itself.
Or D.
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Title | Author | Date |
---|---|---|
Or Duek | Nov 14, 2018 | |
Yuval Argaman | Nov 15, 2018 | |