Scholes-Balog and colleagues followed 852 Australian fifth graders through to the age of 19. They were looking for the factors which explained why some of these students used cannabis early (before age 15), late (after 15), or abstained from cannabis use altogether.By making risk indexes (representing a lot of factors) for community, family, school, peer, individual, and early drug use, the study shed light on which factors could best predict the cannabis usage of these students. Substance use (alcohol, cigarettes, drugs other than cannabis) was the greatest independent predictor for early onset cannabis use. Antisocial families with poor management also predicted cannabis use. In general, the delayed onset and abstinence from cannabis are more likely with increased protective factors (such as healthy socialization) and reduced risk factors.