Dear All,
I am currently analyzing a slightly unusual design which I'm not completely
sure how to set up in FSL. The design is an incomplete 2x2x2-factorial
design. The design was blocked with all 6 conditions performed within one
run in counterbalanced order.
What I've done is the following: There are 6 EVs per subject, specifying the
onsets of the 6 conditions. The EVs represent the following factor-level
combinations:
EV1 = A1B1C1
EV2 = A2B1C1
EV3 = A1B1C2
EV4 = A2B1C2
EV5 = A1B2C1
EV6 = A2B2C1
I set up the following contrasts (for brevity, I skip the reverse contrasts):
A1 vs. A2: 1 -1 1 -1 1 -1
B1 vs. B2: 1 1 0 0 -1 -1
C1 vs. C2: 1 1 -1 -1 0 0
Interaction AxB: 1 -1 0 0 -1 1
Interaction AxC: 1 -1 -1 1 0 0
(interactions display areas with overadditive activation)
My questions are:
- Is it possible to set up the analysis this way?
- I noticed that the 2007 course slides suggest a different way to set up a
2x2-factorial design (EV1 models A1, EV2 models B1, EV3 models the
interaction, F tests are conducted). Would this be a better way or an
alternative way? If this approach were to be preferred, how would I have to
adapt it to my design?
Any help would be greatly appreciated.
Cheers,
Jan
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