The current analysis is similar to that described by the International Schizophrenia Consortium (2009), with two primary differences. First, our total sample was split into training and testing samples based on random assignment, rather than by sex. Second, due to the limited number of SNPs tested, SNPs were included in the “risk” score one at a time, rather than in clusters defined by p-value cut-offs. All analyses were conducted in the open-source statistical package R (R Development Core Team, 2009).
