Microsoft Word Heckman final 2007-03-22c jsb doc
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19 A large literature has established the importance of both cognitive and noncognitive ability in social and economic life. Basic intelligence, acquired skills, social skills, self-control, and persistence matter for success in life (see Heckman et al., 2006, for recent evidence). The full implications of this body of evidence have not yet made their way into the design of economic and social policy. Cameron and Heckman (1999, 2001) document that substantial gaps in the college-going rates of different racial and ethnic groups, which are nominally due to gaps in parental family income in the college-going years, are actually due to ability differences—that is, child college readiness. Adjusting for ability, family income and tuition play only minor roles in accounting for disparity in college attendance rates. This evidence explains why so many poor or disadvantaged children fail to utilize the programs that subsidize the college tuitions of the disadvantaged. In the next section, we show that the ability gaps that explain college attendance gaps open up early, before schooling begins. A school-based policy for eliminating these gaps is less effective. Ability formed in the early years is also important in explaining crime, teenage pregnancy and a variety of social pathologies. Figure 8a shows that women with low cognitive ability are more likely to bear children when they are young. Figure 8b shows that low cognitive ability is associated with a higher probability of incarceration. Ability also affects the economic return to each year of schooling. Figures 8c-d show that mothers with low cognitive ability provide less cognitive and emotional stimulation for their children. Finally, in their research, Carneiro and Heckman (2003) show that the economic returns to one year of college for people of different ability differ greatly. 39 Those at the bottom 5% of the ability distribution get half of the return to education of those at the top 5% of the ability distribution. Ability also affects wages independently of schooling, as shown in Carneiro, Heckman, and Masterov. Heckman, Stixrud, and Urzua analyze the changes in the probability of various outcomes
20 that are brought about by altering cognitive or noncognitive ability, holding the other constant. Figure 9a, taken from their study, clearly shows that higher levels of both cognitive and noncognitive skills are associated with lower rates of attrition from high school. For many outcome measures in their study, increasing noncognitive ability by the same percentile has a higher effect on outcomes than cognitive ability. Increasing noncognitive ability to the highest level reduces the probability of being a high school dropout to virtually zero for females with average cognitive ability. 40 The same argument holds for other behavioral outcomes. Both types of ability have the same effect on reducing the likelihood of spending time in jail by age 30 (see figure 9b). Figure 9c shows the same effect for smoking. Figure 9d show this for teenage pregnancy. For this outcome, noncognitive ability is as important as cognitive ability. 41
Human Ability and Its Determinants The recent synthesis of neuroscience and social science has produced a much deeper understanding of the processes by which skills are formed over the life cycle, although much remains to be known (see Shonkoff and Phillips; Knudsen et al.; and Cunha and Heckman, 2007). The social science literature establishes that both cognitive and noncognitive abilities affect schooling attainment, participation in welfare, teenage pregnancy and crime (see Heckman et al., 2006, for a comprehensive analysis). More able and engaged parents produce more able children. The recent literature distinguishes between IQ and achievement tests. IQ approximates intellectual capacity. Achievement tests capture knowledge in specific areas. IQ spurs achievement. At the same time, persons more motivated to learn and more persistent, and those who plan ahead—important aspects of noncognitive skills—also score higher on achievement tests at the same level of IQ. Families produce both cognitive and noncognitive skills, and both 21 matter for the social and economic success of the child. Gaps among income and race groups open up early and persist. Figure 10a presents the average percentile ranks on a math test administered at ages 6, 8, 10 and 12 for children from different income groups. The test measures a composite of raw IQ and achievement. 42 Gaps in ranks by family income are substantial overall. Figure 10b shows that these differentials are greatly reduced when the scores are adjusted by mother’s IQ, education, and intact family status. Similar adjustments appear when the mother’s status is controlled for, and when other test scores are used. Enriched environments produce higher ability children. 43
antisocial score stands for a range of behavioral problems. High scores are associated with low- income environments; low scores with high-income environments. Again, gaps open up early among income groups, and again, gaps can largely be eliminated by accounting for the quality of the early environments facing the child. 44 A large body of literature, surveyed in Carneiro and Heckman (2003) and Cunha, et al., demonstrates that skill gaps open up early, before schooling begins, and that these gaps are major determinants of social and economic success. The strong association between family characteristics and child performance measured by cognitive and noncognitive skills also demonstrates the value of a strategy targeted toward disadvantaged families.
The policy implications of the emerging body of evidence on the technology of human skill formation are substantial. Conventional school-based policies start too late to effectively remedy early deficits, although they can do some good. The best way to improve the schools is to
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