In order to create an index of pubertal timing, the pubertal status scores for males and for females were standardized by age to provide an index of the timing of physical maturation compared to same-age same-sex peers (Ge et al., 2007). Standardizing within age (11, 12, 13, 14 years) and gender produces a pubertal timing variable with a mean of 0 and standard deviation of 1. Pubertal timing groups were created whereby adolescents who scored within one standard deviation of the mean were classed as on-time. Those who scored more than one standard deviation above the mean were classed as early maturers and adolescents who scored more than one standard deviation below the mean were classed as late maturers.
