Bell Curve

670 Notes to pages 46-47 Notes to pages 50-53 6 7 1proximately two-thirds of a standard deviation above the mean (the meanof incoming freshmen was .48 SDs above the mean), and from the Brighamdata that the graduates of the Ivy League and Seven Sisters were approximately1.25 SDs above the mean (they were 1.1 SDs above the mean asfreshmen, and the Ivy League graduated extremely high proportions of theincoming students).32. The distributions for the main groups are based on the NLSY, for youthswho came of college age from 1981 to 1983 and have been followed throughthe 1990 interview wave. The top dozen universities are those ranked 1through 12 in the U.S. News B World Report survey for 1990. U.S. NewsB World Report, October 15, 1990, pp. 116-134. The analysis is based onpblished distribution of SAT-Verbal scores, which is the more highly g-loaded of the SAT subtests. The estimated verbal mean (weighted by sizeof the freshman class) for these twenty schools, based on their publishedSAT distributions, is 633. The estimated mean for graduates is 650(dropout rates for these schools are comparatively low but highly concentratedamong those with the lowest entering scores). This compareswith a national SAT-Verbal norm estimated at 376 with an SD of 102(Braun, Centra, and King, 1987, Appendix B). The distribution in the figureon page 46 converts the SAT data to standardized scores. The implicitassumption is that AFQT (Armed Forces Qualification Test, an intelligencetest discussed in Appendix 3) and SAT-Verbal measure the samething, which is surely wrong to some degree. Both tests are highly g-loaded,however, and it is reasonable to conclude that youths who have a mean2.5 SDs above the mean on the SAT would have means somewhere closeto that on a full-fledged mental test.33. We have defined these as the first twelve of the listed universities in theU.S. News B World Report listing for 1990. They are (in the order of theirranking) Harvard, Stanford, Yale, Princeton, Cal Tech, MIT, Duke, Dartmouth,Comell, Columbia, University of Chicago, and Brown.34. The probabilities are based on the proportions of people entering thesecategories in the 1980s, which means that they become progressively toogenerous for older readers (when the proportion of people getting collegedegrees was smaller). But this is a technicality; the odds are already so tinythat they are for practical purposes unaffected by further restrictions. Thefigure for college degrees reflects the final educational attainment of membersof the NLSY, who were born in 1957 through 1964, as of 1990 (whenthe youngest was 25), as a weighted proportion of the NLSY population.The figure for Ph.D., law, and medical degrees is based on the number ofdegrees awarded over 1980-1989 expressed as a proportion of the populationage 26 in each of those years. The figure for graduates of the dozenelite schools is based on the number of undergraduate degrees awarded bythese institutions in 1989 (the figure has varied little for many years), expressedas a proportion of the population age 22 in 1989 (incidentally, thesmallest cohort since the mid-1970s.)35. Based on the median percentages for those score intervals among thoseschools.Chapter 21. Hermstein 1973.2. For a one-source discussion of IQs and occupations, see Matarazzo 1972,Chap. 7. Also seelencks et al. 1972 and Sewell and Hauser 1975 for comprehensiveanalyses of particular sets of data. The literature is large and extendsback to the early part of the century. For earlier studies, see, forexample, Bingham 1937; Clark and Gist 1938; Fryer 1922; Pond 1933;Stewart 1947; Terman 1942. For more recent estimates of minimum scoresfor a wide variety of occupations, see E. F. Wonderlic & Associates 1983;U.S. Department of Labor 1970.3. Jencks et al. 1972.4. Fallows 1985.5. The Fels Longitudinal Study; see McCall 1977.6. The correlation was a sizable .5-.6, on a scale that goes from -1 to +l. SeeChapter 3 and Appendix 1 for a fuller explanation of what the correlationcoefficient means. Job status for the boys was about equally well predictedby childhood IQ as by their completed educational levels; for the girls, jobstatus was more correlated with childhood IQ than with educational attainment.In another study, adult intelligence was also more highly correlatedwith occupational status than with educational attainment (seeDuncan 1968). But this may make a somewhat different point, inasmuchas adult intelligence may itself be affected by educational attainment, incontrast to the IQ one chalks up at age 7 or 8 years. In yet another study,based on Swedish data, adult income (as distinguished from occupationalstatus) was less strongly dependent on childhood IQ (age 10) than on eventualeducational attainment (T. Husen's data presented in Griliches 1970),although being strongly dependent on both. Other analyses come up withdifferent assessments of the underlying relationships (e.g., Bowles and Gintis1976; Jencks 1979). Not surprisingly, the empirical picture, being extremelydiverse and rich, has lent itself to myriad formal analyses, whichwe will make no attempt to review. In Chapters 3 and 4, we present ourinterpretation of the link between individual ability and occupation. Wealso discuss some of the evident exceptions to these findings.7. Many of the major studies (e.g., Duncan 1968; Jencks et al. 1972; McCall1977; Sewell and Hauser 1975) include variables describing familial so-