Dear all,

I am doing a multiple regression analysis with 3 covariates of interest. I know that for testing two-way and three-way interactions I must create new variables by multiplying the covariates of interest. As Freesurfer transforms continuous variables to z score before applying statistic, is it correct to transform to z score the result of the previous multiplication? I am asking this because the result of multiplying two z transformed variables would be different.

Thanks a lot in advance.

Marina