Figure 4.2 presents simulated gains in skills at age 15 as induced by an increase in skills at age 14, by level of skills at age 14 for Korea. It shows that children who start out in different levels of skill deciles gained different amounts of skills in the next period. The effects of increasing social and emotional skills (in this case, children’s sense of responsibility, locus of control and self-esteem) at age 14 on social and emotional skills at age 15 increased with the level of social and emotional skills at age 14 (blue line in Panel B).