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help > three factor ANOVA - or simplify design?
Sep 7, 2020 08:09 PM | preini
three factor ANOVA - or simplify design?
Dear Andrew,
thanks for your help in this forum here, I appreciate it very much.
I'm working on a project with 2 groups (medication group, placebo group) with 2 fMRI sessions, where one session is medication/placebo, and one is a baseline scan.
That means I have subjects from the Placebo group that have one placebo and one baseline scan and vice versa with the medication group.
So, every subject has 2 scans, baseline + placebo or medication.
- I have read that you sometimes advice to simplify the design. Would you advise to just use medication vs. placebo sessions? This would be okay, but my sample size is not that high so I don't want to lose data
- I am not sure if my Design Matrix is correct, as I struggled a bit to put this design into a the DM.
I tried it and tried out several types of DM, but I am not sure if I have done it correctly. Say I have 2 subjects:
M_subj2_post, M_subj1_pre, P_subj4_post, P_subj3_pre
I would code it this way:
1 0 1 1
0 1 0 1
1 0 1 -1
0 1 0 -1
where the last 2 columns are: timepoint (0 for pre, 1 for post) and group (modafanil and placebo group).
I'm looking forward to your advice!
Best,
preini
thanks for your help in this forum here, I appreciate it very much.
I'm working on a project with 2 groups (medication group, placebo group) with 2 fMRI sessions, where one session is medication/placebo, and one is a baseline scan.
That means I have subjects from the Placebo group that have one placebo and one baseline scan and vice versa with the medication group.
So, every subject has 2 scans, baseline + placebo or medication.
- I have read that you sometimes advice to simplify the design. Would you advise to just use medication vs. placebo sessions? This would be okay, but my sample size is not that high so I don't want to lose data
- I am not sure if my Design Matrix is correct, as I struggled a bit to put this design into a the DM.
I tried it and tried out several types of DM, but I am not sure if I have done it correctly. Say I have 2 subjects:
M_subj2_post, M_subj1_pre, P_subj4_post, P_subj3_pre
I would code it this way:
1 0 1 1
0 1 0 1
1 0 1 -1
0 1 0 -1
where the last 2 columns are: timepoint (0 for pre, 1 for post) and group (modafanil and placebo group).
I'm looking forward to your advice!
Best,
preini
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Title | Author | Date |
---|---|---|
preini | Sep 7, 2020 | |
Andrew Zalesky | Sep 9, 2020 | |