Hi AndersonThis is super useful. I will go with the 1 factor 4 levels then. Can you please also elaborate what is NPC ? I also wanted to reconfirm that this is in randomise and not in FEAT. That shouldnt be a problem, right ?
Thanks again and bestQasim
From: FSL - FMRIB's Software Library <[log in to unmask]> on behalf of Anderson M. Winkler <[log in to unmask]>
Sent: Wednesday, June 20, 2018 8:03 AM
To: [log in to unmask]
Subject: Re: [FSL] Design Matrix with 4 groups and 3 sessions in fsl randomiseHi Qasim,
You'd need a repeated-measures ANOVA (1 factor with 3 levels within-subject, 1 factor with 4 levels (groups) between-subjects). Another option, perhaps simpler, is to go with the 1 factor and 4 levels as in the link, and use as input differences between before and after. This can be done up to 3 times (post-pre, 4mo-pre, 4mo-post), and these can be combined with NPC.
Generally speaking, NPC tends to be more powerful than a repeated measures ANOVA, and that's the route I'd take. Even without the combination, running 3 separate smaller designs will be faster than just one big repeated measures design.
All the best,
Anderson
On 14 June 2018 at 07:39, Qasim Bukhari <[log in to unmask]> wrote:
Dear all,We have a question regarding design matrix. We have 4 groups: sham, waiting list, Drug1 and Drug2. Each group has 3 session 3 in the scanner: pre, post and after 4 months. There are different subjects in each group, but the subjects are same within sessions.I originally thought that a two sample paired t test would be best suited and I can test each session at a time for pre vs post. And if something is found significant in for example group 1 pre vs post and not significant in control group pre vs post, then i can consider it significant. However I have just realised that probably a better approach would be to use a 1 factor 4 level anova as described here. Is that the correct design matrix ? But here, the example considers 8 subjects, that means at each level there is a different subject.My question is, was my previous approach correct or should I follow the 1 factor 4 level approach as described below ?
Experimental Designs - No repeated measures. We start considering only designs where there is one scan per subject, that is, no repeated measures.fsl.fmrib.ox.ac.ukAny help will be very appreciated
Thanks and bestQasim
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