Probing interactions in multiple linear regression, latent curve analysis, and hierarchical linear modeling: Interactive calculation tools for establishing simple intercepts, simple slopes, and regions of significance
http://www.people.ku.edu/~preacher/interact/index.html
Simple Slope Syntax for Test of Moderation and Simple Slopes for One Dichotomous or Continuous Moderator Candidate of One Centered IV in SPSS
http://www.johannjacoby.de/stattools/SiSSy1.11.html
