Aptitude, Achievement & Intelligence Scores

The following three surveys, conducted independently of the regular NLSY79 interviews, collected aptitude and intelligence score information: 

• Armed Services Vocational Aptitude Battery (ASVAB), a special survey administered in 1980 to the 1979 sample of NLSY79 respondents (see table 1)
• High School Survey, a 1980 survey of high schools, which used school records to collect scores from various aptitude/intelligence tests and college entrance examinations administered during the youth's high school career (see Table 1)
• Transcript Survey, a 1980-83 collection of high school transcript information, which included the gathering of math and verbal scores from such tests as the Preliminary Scholastic Aptitude Test (PSAT), the Scholastic Aptitude Test (SAT), and the American College Test (ACT) (see Table 1)

Additionally, an abbreviated version of the "Knowledge of the World of Work" scale was directly administered to the young men and women of the NLSY79 as an assessment in 1979.

ASVAB Administration

During the summer and fall of 1980, NLSY79 respondents participated in an effort of the U.S. Departments of Defense and Military Services to update the norms of the Armed Services Vocational Aptitude Battery (ASVAB).  The Department of Defense and Congress, after questioning the appropriateness of using the World War II reference population as the primary basis for interpreting the enlistment test scores of contemporary recruits, decided in 1979 to conduct this new study.  NLSY79 respondents were selected since they composed a nationally representative sample of young people born during the period 1957 through 1964.  This testing, which came to be referred to as the "Profile of American Youth," was conducted according to standard ASVAB procedural guidelines.  

Profile of American Youth:

• Respondents were paid $50.
• Five to ten persons were tested at more than 400 test sites, including hotels, community centers, and libraries throughout the United States and abroad. 
• 11,914 civilian and military NLSY79 respondents (or 94 percent of the 1979 sample) completed this test including: 
  • 5,766 or 94.4 percent of the cross-sectional sample.
  • 4,990 or 94.2 percent of the supplemental sample.
  • 1,158 or 90.5 percent of the military sample.

The ASVAB consists of a battery of 10 tests that measure knowledge and skill in the following areas:

• general science
• arithmetic reasoning
• word knowledge
• paragraph comprehension
• numerical operations
• coding speed
• auto and shop information
• mathematics knowledge
• mechanical comprehension
• electronics information 

The following variables are available for each youth tested: 

• raw scores
• scale scores
• standard errors
• sampling weight
• high school graduation status
• whether the test was completed under normal or altered testing conditions

A composite score derived from select sections of the battery can be used to construct an approximate and unofficial Armed Forces Qualifications Test score (AFQT) for each youth.  The AFQT, developed by the U.S. Department of Defense (DOD), is a general measure of trainability and a primary criterion of enlistment eligibility for the Armed Forces.  Three AFQT percentile scores, an AFQT-1, AFQT-2 and an AFQT-3, were created for each Profiles respondent and are described below. 

AFQT-1: To construct AFQT-1, the raw scores from the following four sections of the ASVAB are summed: 

• Section 2 (arithmetic reasoning),
• Section 3 (word knowledge),
• Section 4 (paragraph comprehension),
• and one half of the score from Section 5 (numerical operations). 

AFQT-2: Beginning in January 1989, DOD began using a new calculation procedure. The numerical operations section of the AFQT-1 had a design inconsistency resulting in respondents getting tests that differed slightly and resulted in slight completion rate differences.

Creation of this revised percentile score, called AFQT-2, involves:

• computing a verbal composite score by summing word knowledge and paragraph comprehension raw scores;
• converting subtest raw scores for verbal, math knowledge, and arithmetic reasoning;
• multiplying the verbal standard score by two;
• summing the standard scores for verbal, math knowledge, and arithmetic reasoning;
• converting the summed standard score to a percentile.

AFQT-3: In 2006 the AFQT-2 scores were renormed controling for age so that the AFQT can be used comparatively with the NLSY97. For this reason NLS staff recommend using the AFQT-3. Although the formula is similar to the AFQT score generated by DOD for the NLSY79 cohort, this variable reflects work done by NLS program staff and is neither generated nor endorsed by DOD.

To calculate the AFQT-3, NLS Program staff first grouped respondents into three-month age groups. That is, the oldest cohort included those born from January through March of 1957, while the youngest were born from October through December 1964, a total of 32 cohorts, with an average of about 350 respondents per cohort (there was one unusually small cohort: the youngest cohort has only 145 respondents). The revised dates of birth from the 1981 survey (R0410100 and R0410300) were used whenever these disagreed with the information from the 1979 survey. With the revised birth dates, a few respondents were born outside the 1957-1964 sampling space of the survey.

Those born before 1957 were assigned to the oldest cohort, while those born after 1964 were assigned to the youngest cohort. ASVAB sampling weights from the Profiles section were used (R0614700). Within each three-month age group and using the sampling weights, staff assigned percentiles for the raw scores for the tests on Mathematical Knowledge (MK), Arithmetic Reasoning (AR), Word Knowledge (WK), and Paragraph Comprehension (PC) based on the weighted number of respondents scoring below each score (ties are given half weight). Staff added the percentile scores for WK and PC to get an aggregate Verbal score (V) for which an aggregated intra-group, internally normed, percentile was then computed. NLS Program staff then added the percentile scores for MK, AR and two times the aggregated percentile for V. Finally, within each group we computed a percentile score, using the weights, on this aggregate score, yielding a final value between zero and 100.  Note there are three implied decimal places.

Data Recovery: 

Based on a search of archival files and an examination of the original ASVAB score sheets, revised correct/incorrect indicators based on the answer key and hard copy were generated for the four tests used for the AFQT – Paragraph Comprehension (PC), Word Knowledge (WK), Arithmetic Reasoning (AR) and Mathematics Knowledge (MK).  Consequently, the variables in the newly released AFQT answer file will, for some respondents, show a different number of correct answers than in the original scoring for these tests. 

Item Response Theory Norms for the AFQT:

Additional norms for the AFQT scales (PC, WK, AR, and MK) were created using Item Response Theory (IRT) theta scores from the three-parameter logistic model (3PL).  IRT jointly estimates item scores and respondent scores via fixed effect estimation. The three parameter logistic model (3PL) also estimates a guessing parameter for each item.  Based on evidence from factor analyses of the unidimensionality of pooled Paragraph Comprehension and Word Knowledge, as well as Arithmetic Reasoning and Mathematics Knowledge, IRT theta scores were also generated for the combined math (AR and MK) and combined verbal (WK and PC) scales. These pooled tests should give better resolution of these two domains.

The IRT theta scores were used to create norms for PC, WK, AR, MK and the combined math and verbal scales.  In norming these tests, respondents were grouped into four-month age intervals for each birth year.  By breaking the norming step into 24 cohorts, we avoid the risk that some might conclude younger respondents have less native ability than older respondents. Within each age group, IRT theta scores were ranked from lowest to highest. Using the ASVAB sampling weights, percentiles were calculated based on the weighted number of respondents scoring below each respondent.

Additional details can be found in Appendix 24: Reanalysis of the 1980 AFQT Data from the NLSY79.

References

Bock, R. Darrell and Moore, Elsie G.J.  Advantage and Disadvantage:  A Profile of American Youth.  Hillsdale, NJ:  Lawrence Erlbaum Associates, 1986.

U.S. Department of Defense.  "Profile of American Youth: 1980 Nationwide Administration of the Armed Services Vocational Aptitude Battery."  Washington, DC:  Office of the Assistant Secretary of Defense (Manpower, Reserve Affairs, and Logistics), March 1982.

U.S. Department of Defense.  "Profile of American Youth: 1980 Nationwide Administration of the Armed Services Vocational Aptitude Battery."  Washington, DC:  Office of the Assistant Secretary of Defense (Manpower, Reserve Affairs, and Logistics), March 1982.