The Bell Curve: Intelligence and Class Structure in American Life (135 page)

6
Locke 1689 Bk. IV, Chap. XX.

7
See, for example, Wills 1978; Beer 1993.

8
Mayo 1942, pp. 77-78.

9
Costopoulos 1990, p. 50.

10
Costopoulos 1990, p. 47.

11
Mayo 1942, p. 78.

12
Costopoulos 1990, p. 47.

13
Quoted in Diamond 1976, p. 16.

14
Costopoulos 1990, p. 48.

15
That fact, combined with the “irresistible corruption” that Adams saw as infecting all political systems, caused him to be deeply pessimistic about the survival of the experiment in human government that he had been so instrumental in founding. He sometimes wondered gloomily whether a hereditary aristocracy on the British model might be necessary to offset the unrestrained avarice and factiousness of Jefferson’s natural aristocracy.

16
Aristotle 1905 ed., p. 207.

17
Hamilton et al. 1787, No. 10.

18
White 1958, p. 122.

19
Huber 1988; Olson 1991.

20
Bureau of Labor Statistics 1982, Table C-23, 1989, Table 42.

21
In 1990 dollars in all cases: the annual income of male year-round, full-time nonfarm, non-mine laborers was $16,843 in 1958. (
SAUS
1970, Table 347). The comparable earnings for “handlers, equipment cleaners, helpers, and laborers” in 1991 was $16,777. U.S. Bureau of the Census, 1992, Table 32. The full-time weekly earnings of “lower-skilled labor” in 1920 was $169 in 1990 dollars, or $8,459 for a fifty-week year (U.S. Bureau of the Census 1975, Series D 765-778).

22
For a full presentation of the following argument, see Murray 1988b, Chap. 12.

23
Wilson 1993.

24
It is doubtless harder even for bright people to lead law-abiding lives when the laws become more complex, but the marginal effects will be smaller on them than on the less bright.

25
Ellwood 1988.

26
For an accessible discussion of the pros and cons of the EITC, see Kosters 1993. A more ambitious approach that we think deserves consideration would replace the entire structure of federal transfers to individuals—income supplements, welfare, in-kind benefits, farm subsidies, and even social security—with a negative income tax of the kind proposed by Milton Friedman in Friedman 1962. Like Friedman, we are attracted to this strategy only if it replaces everything else, a possibility so unlikely that it is hard to talk about seriously. This does not diminish its potential merit.

1
M. W. Brown, What is intelligence, and who has it?
New York Times Book Review,
October 16, 1994, pp. 3-6.

2
Murray 1984, 1988b.

3
Herrnstein 1973.

4
M. Novak, Sins of the cognitive elite,
National Review,
December 5, 1994, pp. 58-61. T. Sowell, Can we find a way to discuss intelligence intelligently?
Washington Times,
October 21, 1994.

5
Ibid., p. 59.

6
Gould 1981; Gardner 1983.

7
Snyderman and Rothman 1988.

8
S. J. Gould, Curveball,
New Yorker,
November 28, 1994, pp. 143-144.

9
Steve Blinkhorn, quoted in B. D. Davis, Neo-Lysenkoism, IQ, and the press,
Public Interest,
no. 73 (1983), 44. The Davis article is an illuminating review of the contrasting receptions of
The Mismeasure of Man
accorded by the press and by the scientific community.

10
J. B. Carroll,
Human Cognitive Abilities: A Survey of Factor-Analytic Studies
(Cambridge: Cambridge University Press, 1993).

11
For examples, see Jensen 1987 or B. Bower, Images of intellect: Brain scans may colorize intelligence,
Science News,
October 8, 1994, pp. 236-237.

12
Mainstream science on intelligence,
Wall Street Journal,
December 13, 1994.

13
For a recent and comprehensive presentation of Rushton’s argument and evidence, see J. P. Rushton,
Race, Evolution, and Behavior
(New Brunswick, N.J.: Transaction, 1994).

14
Ibid., chapter 6.

15
J. Rosen and C. Lane, Neo-Nazis!
New Republic,
October 31, 1994, pp. 14-15; C. Lane, The tainted sources of “The Bell Curve,”
New York Review of Books,
December 1, 1994.

16
L. J. Kamin, Behind the curve,
Scientific American
(February 1995 ) : 99-103.

17
K. Owen, The suitability of Raven’s Standard Progressive Matrices for various groups in South Africa,
Personality and Individual Differences
13 ( 1992): 149-159.

18
F. Zindi, Differences in psychometric performance.
Psychologist 7
(1994): 549-554.

19
Kamin 1995, p. 103.

20
J. J. Heckman, Cracked bell,
Reason
(March 1995): 53.

21
A. Goldberger,
Journal of Economic Literature
33(1995): 762-776.

22
Kamin 1995, p. 102.

23
As I write, I have learned of just one computational error out of the hundreds of statistical results presented in the book, in the table on p. 591 (Appendix 3) in the hardcover edition, caused by the miscoding of nine cases. The numbers have been corrected for this edition. The changes did not require any alteration in the wording of the discussion.

24
R. Nisbett, Race, IQ, and scientism, in S. Fraser (ed. ),
The Bell Curve Wars: Race, Intelligence, and the Future of America
(New York: Basic Books, 1995), p. 45.

25
Jeanne Brooks-Gunn et al., Early intervention in low-birth-weight pre-mature infants,
JAMA
272 (1994): 1257-1262.

26
Howard Gardner, Cracking open the IQ box,
American Prospect
(Winter 1994): 71-80. Lisbeth Schorr and Daniel Schorr,
Within Our Reach: Breaking the Cycle of Disadvantage
(New York: Doubleday, 1988).

1
The figure depicts 250 18-year-old males drawn randomly from the NLSY sample.

2
Based on the NLSY subjects, born from 1957 through 1964, as of 1982, when the youngest was 18 years old, the mean height of contemporary Americans is a little over 5 feet 7 inches, with a standard deviation of about 4 inches.

3
Based on the 1983 ETS norm study (Braun and King 1987) and dropout rates in the 1980s, we estimate the mean for all 18-year-olds (including dropouts) at 325, with an standard deviation of 105. This would indicate that the 99th centile begins at a score of 569. The example in the text is phrased conservatively.

4
The Pearson’s
r
is .501 in both cases. The number 3,068 refers to males with weight and height data in 1982.

5
For simplicity’s sake, we are assuming that the variables can have only linear relationships with each other.

1
The NLSY on CD-ROM disk is available for a nominal fee from the Center for Human Resource Research, Ohio State University.

2
Inquiries should be directed to Prof. Richard J. Herrnstein, Department of Psychology, William James Hall, Harvard University, Cambridge, MA 02138, or to Dr. Charles Murray, American Enterprise Institute, 1150 17th St. NW, Washington, DC 20036.

3
Data for 1991 had become available in time to be used for the analysis, but for budgetary reasons, the NLSY had to cut the supplementary sample of low-income whites as of 1991. We decided that the advantages of including low-income whites in the analysis outweighed the advantages of an additional year of data.

4
We followed the armed forces’ convention of limiting subtest scores to a maximum of three standard deviations from the mean. We gratefully acknowledge the assistance of Dr. Malcolm J. Ree, who led the revision of the AFQT, in computing the revised scores for the NLSY.

5
This procedure is facilitated by the large sample sizes (at least 1,265 with valid AFQT scores in each birth year, which are as large as the samples commonly used for national norms in tests such as the WISC and WAIS), and the fact that the NLSY sample was balanced for ethnic group and gender within birth years.

6
We also experimented with groupings based not on the calendar year, but the school year. The differences in centile produced by the two procedures were never as much as two, so we remained with calendar year as the basis.

7
See
Users Guide
1993, pp. 157-162.

1
The subtests are General Science (GS), Arithmetic Reasoning (AR), Work Knowledge (WK), Paragraph Comprehension (PC), Numerical Operations (NO), Coding Speed (CS), Auto/Shop Information (AS), Mathematics Knowledge (MK), Mechanical Comprehension (MC), and Electronics Information (EL). Two subtests (Numerical Operations and Coding Speed) are highly speeded; the other eight are “power” rather than speed tests.

2
Ree and Earles 1990a, 1990b, 1991c.

3
We use the term
factor
in a generic sense. Within psychometries, terms like
factor
and
component
are used selectively, depending on the particular method of analysis used to extract the measures.

4
E.g., Gould 1981.

5
Jensen 1987a, 1987b; Ree and Earles 1991c; Welsh, Watson, and Ree 1990.

6
To account for literally 100 percent of the variance takes ten factors (because there are ten subtests), with the final few of them making increasingly negligible contributions. In the case of ASVAB, the final five factors collectively account for only 10 percent of the total variance in scores.

7
Sperl, Ree and Steuck 1990.

8
Carroll 1988; Jensen 1987a.

9
Ree and Earles, 1990a, 1990b, 1991c.

10
Gordon 1984; Jensen and Figueroa 1975.

11
Note that the General Science subtest and the Electronics Information subtest are as highly g-loaded as the subtests used in the AFQT. Why not use them as well? Because they draw on knowledge that is specific to certain courses that many youths might not have taken, whereas the mathematics and reading subtests require only material that is ordinarily covered in the courses taken by every student who goes to elementary and secondary school. But this is a good illustration of a phenomenon associated with IQ tests: People who acquire knowledge about electronics and science also tend to have high mathematics and verbal ability.

12
Jensen 1980, Table 6.10.

13
Within a single test, the test score might mean any of several percentile scores, depending on the age of the student; hence the reason for using percentiles. For the analyses in the text, scores were used only if both a test score and a percentile were recorded. Anomalous scores were discarded as follows: For the California Test of Mental Maturity, one test score of 700. For the Otis-Lennon Mental Ability Test, eight cases in which the test score was under 30 and the percentile was over 70; one case in which the test score was 176 and the percentile was only 84. For the Henmon-Nelson Test of Mental Maturity, one test score of 374. For the Differential Aptitude Test, sixteen test scores over 100. For the Lorge-Thorndike Intelligence Test and the Kuhlmann-Anderson Intelligence Test, which showed uninterpretable scatter plots of test scores against percentiles, cases were retained if the test score normed according to a mean of 100 and a standard deviation of 15 was within 10 centiles of the reported percentile score. The number of eligible scores on the Stanford-Binet and the Wechsler Intelligence Scale for Children (18 and 16, respectively) was too small to analyze.

14
Jensen 1980, Table 8.5.

15
This list is taken from Jensen 1980, p. 72. Jensen devotes a chapter (Chap. 4) to the distribution of mental ability, which we recommend as an excellent single source for readers who want to pursue this issue.

16
For an exploration of the relationships as of the late 1960s, see Jencks et al. 1972, Appendix B. For separate studies, see Rutter 1985; Hale, Raymond, and Gajar 1982; Wolfe 1982; Schiff and Lewontin, 1986.

17
Husén and Tuijnman, 1991. See also Ceci 1991, for a case that schooling has a greater influence on IQ than has generally been accepted, drawing heavily on data from earlier decades when the natural variation in schooling was large.

1
Validity is measured by the correlation between predictor and outcome, which, multiplied by the ratio of the standard deviations of the outcome to the predictor, gives the regression coefficient of the outcome on the predictor. To keep this discussion simple, we assume an increasing monotonic relationship between the validity and the regression coefficient here. For a discussion that does not make this simplifying assumption, see Jensen 1980.