Hi Anderson,
Thanks for your reply. I was thinking of including subject-specific variables of interest (as opposed to nuisance variables). For instance, I wanted to include individuals’ performance on a behavioural task (demeaned) to examine how activation within contrasts of interest (linear/quadratic) is modulated by performance. Would this be possible/make sense in this context?
Regarding the reference level, am I right in thinking that the results would be with L1 as reference instead of L5?
To make sure that I understand the logic, do the contrasts below look right?
positive linear: [0 0 0 … 0 0 0 -48 -24 0 24]
negative linear: [0 0 0 … 0 0 0 48 24 0 -24]
n-shape quadratic [0 0 0 … 0 0 0 -48 24 48 24]
u-shape quadratic [0 0 0 … 0 0 0 48 -24 -48 -24]
Best wishes,
Chris
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Hi Chris,
With this design, the contrast to test if each of the 5 levels (L1-L5) are larger than zero are:
C1 (L1 > 0): [1 1 1 .... 1 1 1 24 0 0 0]'
C2 (L2 > 0): [1 1 1 .... 1 1 1 0 24 0 0]'
C3 (L3 > 0): [1 1 1 .... 1 1 1 0 0 24 0]'
C4 (L4 > 0): [1 1 1 .... 1 1 1 0 0 0 24]'
C5 (L5 > 0): [1 1 1 .... 1 1 1 0 0 0 0]'