 42. Some Contributions of Economics to the Study of Personality 873
dropouts, whereas high school graduates 
earn more and have higher hourly wages. 
Adjusting for family background character -
istics does not change the story.70
Causal Evidence from  Intervention  Studies
Predictive studies do not establish causality. 
Most studies in personality psychology do 
not address the question of causality (i.e., 
whether measured skills cause  rather than just predict outcomes). Empirical associa -
tions are not a reliable basis for policy anal -
ysis. In this section, we discuss difficulties 
in establishing causality. We also summarize 
several studies that provide evidence that 
personality skills cause  outcomes.
We introduce a simple framework to an -
alyze the effect of skills on outcomes and 
how skills evolve over time.71 Equation 42.1 
shows how an outcome at age a , Ta, which 
is the performance on a task, depends on 
cognition Ca, personality Pa, other acquired FIGURE 42.10 Survival rates in various states for male dropouts, GED recipients, and high school gradu -
ates (HSG): (a) Survival rate in employment, (b) Survival rate in staying on a job, (c) Survival rate in 
marriage, (d) Survival rate in staying out of jail. Source: Heckman et al. (2014, Chapter 4), NLSY79, 
nationally representative cross sectional sample. Note: The spell to first time being incarcerated begins 
in the first year that individuals exit school. Tests of significance: The estimates for GED recipients and 
HSG are statistically significantly different at the 5% level for all but the second year of “Survival Rate 
in Not Having Been Incarcerated.” The estimates for dropouts and HSG are statistically significantly 
different at the 5% level for all but the second year of “Survival Rate in Not Having Been Incarcer -
ated.” The estimates for dropouts and GED are statistically only significantly different at the 5% level 
for the fifth year of the “Survival Rate in Marriage.”.2.4.6.81Survival Rate in Employed State
1 2 3 4 5 6 7 8 9 10
Years Since Start of Spell
Dropout GED HSGA
0.2.4.6.81Survival Rate in Current Job
1 2 3 4 5 6 7 8 9 10
Years Since Start of Spell
Dropout GED HSGB.4.6.81Survival Rate in Marriage
1 2 3 4 5 6 7 8 9 10
Years Since Start of Spell
Dropout GED HSGC
.85.9.951Survival Rate in Non−Incarcerated State
1 2 3 4 5 6 7 8 9 10
Years Since Start of Spell
Dropout GED HSGD