for each year to estimate how many individuals in the United States each respondent represents.3
Data are collected yearly from 1979 to 1994 and biennially since 1994;4 they provide researchers
an opportunity to study in detail the experiences of a large group of young adults.5 The Appendix
to this paper contains the coding information for the complete set of variables used in the
regressions reported in the paper tables.
The primary focus of the NLSY79 survey is labor force behavior. It includes very
detailed questions on a respondent’s employment status, yearly earnings, measures of actual
labor market experience, tenure with a specific employer, and employer mobility. The survey
also includes a wide range of other variables, such as educational attainment, training
investments, income and assets, health conditions, marital status, and fertility histories. Moreover,
there is an aptitude measure in the NLSY79, namely, the Armed Services Vocational Aptitude
Battery Test (the ASVAB Test). In 1980, 11,878 out of the total 12,686 respondents, which is 94
percent of the whole sample, took the ASVAB Test.
Herrnstein and Murray (1994) endorse a one-dimensional, supposedly time-invariant,
measure of human intelligence, called general intelligence and denoted g. Charles Spearman
(1927), a prominent British psychologist, first proposed that a general component can be
extracted from a battery of mental tests using factor analysis, which is a mathematical
transformation of the correlation matrix. This general component, which Spearman dubbed g,
predicts performance almost as well as the full battery of tests. Spearman’s discovery of g
established the foundation of psychometrics,6 and introduced the idea that cognitive ability might
3 The design of sampling weights involves the reciprocal of the probability of selection at the first interview. See NLSY79 User’s
Guide, Section 2.8
4 Up to the completion of the calculations reported herein, the latest NLSY79 survey year with available data is 2002.
5 NLSY79 User’s Guide, Section 2.8, p.3.
6 Psychometrics is a branch of psychology that deals with the design, administration, and interpretation of quantitative tests for
the measurement of psychological variables such as intelligence, aptitude, and personality traits.