I'm working a study to assess the relationship between psychotic symptoms and suicide ideation on adolescents. A battery of instruments was applied to 1635 adolescents from 2 contexts (Group A=School sample, n=1520; Group B=Clinical sample, n=115) to assess psychotic symptoms and suicide ideation.
I want to know if higher scores on psychotic symptoms are able to predict higher scores on suicide ideation. The thing is, none of the variables have a normal distribution.
My question is, do simple and/or multiple linear regression models need the variables to have a normal distribution? I've read both that they do and that they don't. If they don't, why? If they do, what kind of non-parametric analysis should I use?
Thanks in advance.