Fig. 1. Structural equation model of the associations among childhood IQ, sex (1 = male, 2 = female), social class (lower numbers = higher social class), deprivation (higher numbers = more deprivation), and mortality (1 = alive, 2 = dead). Coefficients placed beside arrows may be squared to give the variance shared by adjacent variables. ⁺p.1; * p.05; ** p.01; *** p.001.