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help > RE: 2x2 ANOVA setup
Oct 2, 2015 01:10 PM | Lars Michels
RE: 2x2 ANOVA setup
Dear Greg and Alfonso
I have a quite similar design (2 groups and for each of them I do have a pre and post (training) scan). I also want to test for main effects (F test).
During each scan I have resting and taks periods.
First, I am not sure how to set up the design matrix for this 2 x 2 ANOVA
Lets say, there are 4 controls and 4 patients. Do I have to choose 8 subjects or 16 in the Setup menu? For example, If have select 8, I could define two groups (2nd level covariates) and two conditions (pre and post). But then I cannot assign separte scans for each of them (Since I have only 1 session). Hence, I could still use 8 subjects in total but have to use 2 sessions for each subject and assign e.g. session 1 as the pre scan and session 2 as the post scan, right? However, the question is whether "pre" and "post" are still listed as Conditions in the 2nd level tab later on?
Alternatively, I could select 16 subjects, and code as controls_pre controls_post patients_pre patients_post (2nd level covariates) and as conditions still pre and post, e.g.
controls_pre [1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0], controls post [ 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 0] etc.
I tested this. And yes, 4 groups and 2 conditions (pre/post) appear in the second level tab. But this is wrong, I think, as I do have only two groups (controls and patients) with repeated measures (pre and post).
Again, I wanted to run F-test first (and then t-tests).
Which of the Design scenarios is the correct one to choose?
Finally, I wanted to compute background connectivity (time bin: 0 inf) and task PPI connectivity. Does this mean I have to simply add some extra conditions, e.g. pre_background (0-inf) and pre_task (e.g. onset 20 40 60, duration 10) to be able to compute both background and PPI connectivity.
Thanks
Lars
I have a quite similar design (2 groups and for each of them I do have a pre and post (training) scan). I also want to test for main effects (F test).
During each scan I have resting and taks periods.
First, I am not sure how to set up the design matrix for this 2 x 2 ANOVA
Lets say, there are 4 controls and 4 patients. Do I have to choose 8 subjects or 16 in the Setup menu? For example, If have select 8, I could define two groups (2nd level covariates) and two conditions (pre and post). But then I cannot assign separte scans for each of them (Since I have only 1 session). Hence, I could still use 8 subjects in total but have to use 2 sessions for each subject and assign e.g. session 1 as the pre scan and session 2 as the post scan, right? However, the question is whether "pre" and "post" are still listed as Conditions in the 2nd level tab later on?
Alternatively, I could select 16 subjects, and code as controls_pre controls_post patients_pre patients_post (2nd level covariates) and as conditions still pre and post, e.g.
controls_pre [1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0], controls post [ 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 0] etc.
I tested this. And yes, 4 groups and 2 conditions (pre/post) appear in the second level tab. But this is wrong, I think, as I do have only two groups (controls and patients) with repeated measures (pre and post).
Again, I wanted to run F-test first (and then t-tests).
Which of the Design scenarios is the correct one to choose?
Finally, I wanted to compute background connectivity (time bin: 0 inf) and task PPI connectivity. Does this mean I have to simply add some extra conditions, e.g. pre_background (0-inf) and pre_task (e.g. onset 20 40 60, duration 10) to be able to compute both background and PPI connectivity.
Thanks
Lars
Threaded View
Title | Author | Date |
---|---|---|
Greg Book | Mar 12, 2014 | |
Alfonso Nieto-Castanon | Apr 14, 2014 | |
Victor Pando-Naude | Feb 1, 2023 | |
Amy Bouchard | Mar 27, 2020 | |
Alfonso Nieto-Castanon | Mar 28, 2020 | |
Amy Bouchard | Mar 28, 2020 | |
Bruno Baumann | May 2, 2016 | |
Lars Michels | Oct 2, 2015 | |
Alfonso Nieto-Castanon | Oct 5, 2015 | |
Lars Michels | Oct 6, 2015 | |
Alfonso Nieto-Castanon | Oct 8, 2015 | |
Lars Michels | Oct 8, 2015 | |
Alfonso Nieto-Castanon | Oct 9, 2015 | |
Greg Book | Mar 31, 2014 | |