Hi,
I am conducting a ROI analysis to explore the interaction effect of two of my covariates (A and B) in amygdala activation. It is a within subject design, with quantitative and continues VD and VIs and I used multiple regression.
My matrix has five columns: mean baseline, covariate A, covariate B, covariate C and covariate D (Baseline A B C D)
In order to explore a positive interaction between covariate A and B, I defined the contrast vector as: 0 1 1 0 0
And to explore a negative interaction between covariate A and B, I defined the contrast vector as: 0 -1 -1 0 0
Does it make sense? Does anyone suggest another way to define the contrasts?
Thanks in advance!
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