Monthly Labor Review February 2005 15

Kenneth I. Wolpin

NLSY79 Education Data

Education data in the NLSY79:

a premiere research tool

P

erhaps the most widely used data in social science research are those related to

measures of education; among such measures, years of schooling is the most ubiquitous. A search of the National Longitudinal Survey (NLS) Annotated Bibliography yields 1,803

articles, book chapters, dissertations, and so

forth, in which either the word “education” or

“schooling” appears in the title, abstract, or as

a keyword.1 Of those, more than 1,000 were

based on the National Longitudinal Survey of

Youth, 1979 (NLSY79) data.2

Researchers’ use of education measures

found in the NLSY79 spans several social science disciplines, particularly economics and

sociology, and, to a lesser extent, psychology.

A large number of articles using NLSY79 education measures have appeared in major general

audience and specialty journals. (See table 1.)3

In economics, there were 8 such journals, totaling 78 published articles, and in sociology,

6 journals with 47 articles. In psychology, one

journal specializing in child development published five articles, and one medical science

journal also published five.4

The topics covered in these articles vary

widely, as is evident from looking at the titles

of the journals. These articles can be classified

into two broad categories: (i) articles that study

schooling decisions themselves (for example,

how much schooling to complete, whether to

drop out of high school, or choice of college

major), and (ii) articles that study the “effect”

Kenneth I. Wolpin is a

professor at the

University of

Pennsylvania

Department of

Economics.

E-mail:

wolpink@ssc.upenn.edu

Social science researchers widely use

the NLSY79 schooling data

because of its longitudinal nature and range of content

of schooling on some other decision or outcome

(for example, on wages, fertility, or alcohol consumption). In both cases, the NLSY79 data is

chosen for its omnibus nature (that is, the data

include information other than schooling), and

because the data are longitudinal.

Although the NLSY79 was a pathbreaking survey in many ways, the collection of schooling

data has been relatively standard. The education section in 1979, the first year of the survey,

contained a total of just 25 questions (excluding interviewer check items), although respondents were attending school levels ranging from

junior high through college.5 In the first follow-up survey in 1980, respondents were asked

just 16 questions, primarily to update the

baseline schooling information obtained in the

1979 survey round. Essentially, the same questions were asked in the second follow-up in

1981, with the important addition of a monthly

attendance record obtained retrospectively back

to January 1980. This addition was in keeping

with the event history format of the NLSY79 with

respect to the collection of employment data

and was continued throughout all subsequent

rounds. The schooling section was unchanged

until 1984, when an extensive set of questions

was added to obtain information on colleges attended by respondents. Again, in keeping with

the overall format of the survey, the aim was to

obtain an event history of college attendance.

The rostering of colleges attended continued

prospectively through 1990, when the young-
16

NLSY79 Education Data

Monthly Labor Review February 2005

est respondents were age 25. The major elements of the

schooling data in the main survey include current school enrollment status, highest grade attended and completed, high

school curriculum, major field of study in college, degrees

obtained, names and locations of colleges attended, college

loans, and the schooling of household members.

Along with the main survey, there are several supplemental data collections pertinent to schooling. The School Survey, given in 1980, collected information from school administrators on school characteristics. The High School Transcript Survey collected and coded high school transcripts for

almost 9,000 of the respondents. Finally, the Children of the

NLSY79, begun in 1986, collected child development data for

all children born to the women of the NLSY79.

It is beyond the scope of this article to summarize the findings from the studies cited above; instead, some data are presented that fit with the purpose of this special issue, that of

celebrating the 25th anniversary of the NLSY79. In that vein,

the data presented illustrate the aforementioned two most important features of the survey, the longitudinal nature and the

range of content. These features are highlighted by documenting differences among completed schooling groups in a wide

array of behaviorally-related characteristics. (See table 2.)

Cumulative differences are shown for many characteristics

over a substantial post-schooling age range. The table makes

clear the rationale for the intensive study of schooling by social scientists, and for the popularity of using the NLSY79 data.

In the table, schooling is based on completed years of

schooling as of age 25 and is divided into five categories:

high school dropouts (completed years of schooling reported

to be less than 12) who have not received a GED, high school

dropouts who have received a GED, high school graduates

(completed years of schooling exactly 12, no GED), those with

some college (completed years of schooling between 13 and

15), and college graduates (completed years of schooling 16

or more). The table, based on data through the 2000 survey,

considers differences in earnings, welfare takeup and payments, unemployment, hours worked, financial asset holdings, health status, obesity, alcohol consumption, fertility, and

birth weight and test scores of the first-born child.

About 20 percent of males and 17 percent of females in

this cohort did not complete high school with a regular diploma; of those, about a third received a GED. Notice that

counting a person with a GED as a high school graduate makes

a nontrivial difference to the calculation of the dropout rate.6

A little less than 40 percent graduated high school with a

diploma and did not complete any further schooling. The rest,

about 40 percent of the cohort, went on to college, and about

half of those graduated.

The cumulative figures in the table span ages from 25

through 39. However, many of the variables are not available in every year. Thus, cumulative variables, such as total

earnings or weeks of unemployment, would be understated.

Averaging available data and multiplying by 15 would provide an unbiased estimate except that missing values tend to

occur more frequently at the older ages, both because of attrition and because the survey became biannual after 1994,

and many of the variables are age-trended. To obtain an estimate of the cumulative values, averages of three 5-year age

intervals (ages 25–29, 30–34, and 35–39) were calculated,

each average was multiplied by 5, and then the three totals

were added together. As long as the age trends are not severe

within each of the 5-year age intervals, this procedure should

provide a reasonable estimate.

The most striking feature of the table is how different high

school dropouts, particularly those without GED’s, and college graduates are relative to the rest. Following is a breakdown of each characteristic in turn.

Earnings. There are two sources of information on earnings in the NLSY79: a global question on the amount of wage

and salary income in the previous calendar year, and earnings obtained from the event history on reported jobs. The

figures in the table come from the former source and are in

1996 dollars.7 Over the 15-year period between the ages of

25 and 39, a male high school dropout without a GED earned,

on average, $273,250, about $30,000 less than a high school

dropout with a GED, and $150,000 less than a high school

graduate with a regular diploma. On the other end of the eduTable 1. Number of articles published since 1990 with

“education” or “schooling” as a keyword in the

title or in the abstract: journals with five or more

articles by field

Number

Field / journal of

articles

Economics:

American Economic Review ........................... 10

Economics of Education Review ..................... 7

Industrial and Labor Relations Review ............. 11

Journal of Human Resources ......................... 18

Journal of Labor Economics ........................... 7

Journal of Political Economy ........................... 5

Monthly Labor Review ................................... 10

Review of Economics and Statistics ................ 13

Sociology, demography:

American Sociological Review ........................ 6

Demography ................................................ 8

Family Planning Perspective........................... 8

Journal of Family Issues ................................ 6

Journal of Marriage and the Family ................. 10

Social Forces ............................................... 9

Psychology:

Child Development ........................................ 5

Others:

Pediatrics ..................................................... 5
Monthly Labor Review February 2005 17

Table 2. Selected characteristics by completed schooling

Percent .................... 13.7 6.2 37.9 20.4 21.8 11.5 5.4 39.7 23.2 20.3

Cumulative earnings 1

Age 25–39 ............ $273,250 $305,041 $429,813 $486,619 $775,206 $113,521 $187,214 $207,738 $284,859 $426,855

Cumulative welfare

payments1

Age 25–39 ......... $7,004 $7,185 $2,447 $1,216 $346 $28,032 $16,477 $8,198 $4,285 $271

Percent of years

receiving welfare

Age 25–39 .......... 13.3 10.6 4.5 2.8 .5 31.0 19.7 10.7 5.4 .7

Cumulative weeks

unemploy ed

Age 25–39 ......... 71.9 60.3 36.5 31.0 11.3 53.3 47.8 33.7 24.0 12.2

Cumulative hours

worked: full-time

(2,080 hours) year

equivalents

Age 25–39 ......... 13.1 12.7 15.6 15.3 16.6 7.3 9.6 10.4 11.2 12.2

Change in financial

assets between

1985 and 2000

10th percentile .... –543 –814 –1,357 –2,360 –2,474 –87 –679 –1,368 –2,035 –950

50th percentile .... 0 0 977 1,928 19,347 0 0 467 1,868 12,927

90th percentile .... 4,671 7,865 31,805 55,119 268,212 3,661 8,517 20,642 67,953 178,281

Percent reporting

health limitation,

age 25–39

At least once ...... 36.4 32.2 21.1 18.4 9.0 51.6 36.1 36.0 31.7 21.1

At least 50 percent

of the years ..... 7.4 8.1 3.1 3.2 1.0 10.1 9.8 4.4 4.8 1.9

Percent obese

(BMI greater than

or equal to 30),

age 25–39

At least once ...... 35.7 25.8 33.2 29.7 18.7 39.3 30.7 32.2 27.5 17.8

At least 50 percent

of the years ..... 16.3 12.2 17.8 16.2 8.2 26.1 18.7 17.1 14.7 6.2

Number of days per

month having had six

or more alcoholic

drinks

Age 18–24 ......... 1.97 1.78 1.70 1.40 1.39 .80 .59 .46 .40 .54

Age 25–34 ......... 1.21 .86 .98 .93 .61 .39 .55 .27 .17 .14

Number of children ever

born, greater than or

equal to age 35 ...... 1.9 1.9 1.6 1.4 1.5 2.6 2.3 1.9 1.7 1.6

Percent at first birth,

less than or equal

to age 19............... 23.9 23.7 8.8 4.2 1.1 68.4 55.6 26.1 11.1 .7

Birth weight of first

born (ounces) ........ – – – – – 113.2 115.4 117.0 116.4 117.9

PPVT percentile score

of first born ............ – – – – – 30 41 43 49 63

High school dropout High school dropout

No GED GED No GED GED

High

school

graduate

High

school

graduate

Some

college

Some

college

College

graduate

College

graduate

Males Females

Characteristic

1 1996 dollars NOTE: All figures use the 1979 sample weights. Dash indicates data not available.
18

NLSY79 Education Data

Monthly Labor Review February 2005

cation spectrum, a male college graduate earned $775,206,

almost $300,000 more than a male who completed some college. Female differences by education are smaller in absolute

value, in part because they work less (see below). Nevertheless, a female high school graduate earned about $90,000

more than a dropout without a GED, and about $75,000 less

than what a female who completed some college earned. A

female college graduate earned $426,855, about $140,000

more than a female with some college.

Welfare payments and takeup. The NLSY79 collects data on

takeup and payments for several welfare programs. The figures in the table aggregate respondent information about the

Aid to Families with Dependent Children (AFDC), Food Stamp,

and Supplemental Security Income (SSI) programs. Because

of AFDC, aggregate welfare payments and takeup are much

larger for females than for males. Over the 15 years, female

high school dropouts without a GED received welfare on average in about 30 percent of the years, totaling $28,032. In contrast, high school dropouts with a GED received welfare in

about 20 percent of the years, totaling $16,477. Comparable

figures for high school graduates were about 11 percent of

the years and $8,198, and for those with some college, 5 percent of the years and $4,285. Female college graduates, on

average, essentially received no welfare.

Perhaps somewhat surprisingly, as seen in the table, even

female high school dropouts without a GED had considerably

more market earnings over the period than they received in

welfare. In fact, only 35 percent of these women reported

receiving more in welfare payments than they earned over

the period. In contrast, 16 percent of high school dropouts

with a GED, 10 percent of high school graduates, and 4 percent of those with some college received more welfare over

the 15 years than they earned.

The takeup rates and average payments for males are, as

noted, considerably smaller than for females; for example,

male high school dropouts without a GED received some welfare in only 13 percent of the years, about the same as those

with a GED. Welfare payments over the entire 15-year period

were, on average, only about $7,000 for high school dropouts

regardless of GED status, and only 7 percent of dropouts without a GED received more in welfare benefits than they earned.

Labor force status (unemployment and hours worked). Male

high school dropouts without a GED were unemployed 72

weeks, and similar female dropouts were unemployed 53

weeks, cumulatively over the 15-year age period.8 These figures are slightly higher than for dropouts with a GED. Those

who graduated from high school or completed some college

had significantly fewer cumulative weeks of unemployment.

However, as with earnings and welfare, college graduates

were distinctly different than the other schooling groups; male

(female) college graduates spent only 11 (12) weeks unemployed over the 15 years. With respect to the amount of time

spent working, measured in full-time year equivalents (2,080

hours), on average male dropouts (those with and without a

GED) worked about 13 of the 15 years, while male college

graduates worked more than full-time, 16.6 years or about

2,300 hours per year. In contrast, female dropouts without a

GED worked less than one-half of the years, while college

graduates worked four-fifths of the years.

Financial asset accumulation. The NLSY79 began collecting

asset data in 1985. Table 2 presents statistics on the amount of

financial assets accumulated from the first report (when respondents were 20 to 28 years of age) to the 2000 report (when

respondents were 35 to 43).9 Differences in financial savings

by schooling are large, although the relationship is quite

skewed. Median financial savings are zero for high school

dropouts of both sexes, slightly negative at the 10th percentile, and less than $10,000 at the 90th percentile. Median savings is less than $2,000 for those with some college, but savings increase to $55,000 for males and $68,000 for females at

the 90th percentile. College graduates are again different than

other schooling groups in terms of their financial savings. Median financial savings of males is almost $20,000, but more

than $250,000 at the 90th percentile; for females, the median

is about $13,000 and the 90th percentile, $178,000.

Health. In each round of the NLSY79, respondents were

asked separately about whether their health limited the amount

or the kind of work they could perform. Table 2 presents data

on the distribution of the number of times between the ages of

25 and 39 that the respondent answered affirmatively to either question.10 The first row reports on the percent who gave

an affirmative response at least once, and the second row, on

the percent who gave an affirmative response in at least 50

percent of the years. High school dropouts without a GED are

the most prone to report a health limitation affecting work at

least once; more than a third of the men and more than half of

the women reported ever having a limitation. At the other

extreme, only 9 percent of male college graduates, and 21

percent of female college graduates, reported such an occurrence at least once. Chronic health conditions, as measured

by having reported a health limitation in at least half of the

years, are much less prevalent in all schooling groups, but

non-negligible for high school dropouts. Between 7 percent

and 8 percent of male high school dropouts, and about 10

percent of female high school dropouts, have a persistent

health condition, while this is true of only 1 percent of male

and 2 percent of female college graduates.

Obesity. The NLSY79 collected self-reported information on

a respondent’s height and weight in 1981, 1982, and 1985,
Monthly Labor Review February 2005 19

and on the respondent’s weight in all rounds since 1986, except 1987 and 1991. Body mass index (BMI) was calculated

in each year using the latest height information that was available.11 As with health limitations, table 2 reports the distribution of the number of times over the 15-year age period, 25–

39, that respondents have a BMI of 30 or more, indicating

obesity, again by schooling groups for each sex. Although

there is some prevalence of obesity among males with schooling below college completion, it is not large. Among males

with some college, 30 percent were obese in at least 1 year,

and 16 percent were obese in at least one-half of the years.

The same figures for high school dropouts are 36 percent

and 16 percent. Differences are larger for females, with 28

percent of those with some college, and 39 percent of high

school dropouts without a GED, being obese in at least 1 year.

College graduates again are substantially different from all

of the other groups. For both sexes, less than 20 percent were

obese in any year, and less than 10 percent in at least half of

the years.

Alcohol consumption. In several years (1982, 1983, 1984,

and 1994), the NLSY79 has included a section of questions,

funded by the National Institute of Alcohol Abuse and Alcoholism (NIAAA), on alcohol use. A common question in those

rounds has been the number of days in the last month that the

respondent consumed six or more drinks. Table 2 shows the

average number of days over all of the observations in those

years for two age intervals, 18–24 and 25–34, by schooling

and sex. In all of the schooling groups, for both males and

females, alcohol consumption measured in this way fell substantially with age. Male high school dropouts without a GED

averaged just less than 2 days a month between the ages of

18 and 24, but 30 percent less between 25 and 34. Females

within that schooling group averaged only .8 days at the earlier age, but that fell in half at the later age. College graduates are less of an outlier in terms of alcohol consumption at

the earlier age, although their consumption falls proportionately more at the later age.

Fertility. Differences by schooling in the number of children ever born by age 35 are large. Female high school dropouts who have not earned a GED have had 2.6 children on

average by age 35, .3 more than their counterparts with a

GED, .7 more than those with a high school diploma, .9 more

than those with some college, and a full child more than those

with a college degree. Males at all schooling levels report

having had fewer children, and this is particularly pronounced

for high school dropouts. Even so, those male respondents

with some college report having fathered half a child less

than those who were high school dropouts.

Schooling differences in fertility are even more striking in

terms of the prevalence of teenage childbearing. More than

two-thirds of female high school dropouts without a GED, and

more than one-half of those with a GED, gave birth to a child

as a teen. This figure drops to one-quarter for high school

graduates, to about 10 percent for those with some college,

and to less than 1 percent for college graduates.

Birth weight of children. Starting with the 1982 survey

round, with funding from the National Institute of Child

Health and Human Development (NICHD), the NLSY79 collected information about the pregnancy outcomes of the female respondents.12 Table 2 compares mean birth weight of

first-born children across the schooling groups.13 The differences observed among the respondent’s own outcomes, such

as earnings and health, also emerge among the children of

the respondents. High school dropouts without a GED have

the lowest birth weight of children, almost 5 ounces less than

the first births of the college graduates.

Peabody Picture Vocabulary Test (PPVT) scores of children.

The Children of the NLSY79 survey was started in 1986 and

obtains information about the children born to the women of

the NLSY79, including cognitive test scores. Table 2 reports

the mean percentile scores (age adjusted) of first-born children by mother’s schooling. As seen repeatedly in the table,

the lowest and highest schooling groups, high school dropouts without a GED and college graduates, appear to be outliers. Children of the former group have mean scores that fall

in the 30th percentile, while those of the latter fall in the 63rd

percentile. The other three schooling groups fall in between

and differ only slightly from each other.

THIS OVERVIEW analyzes the contributions of the NLSY79 to

the study of issues related to education. Space limitations,

combined with the vastness of the literature, precluded a critical assessment of the scientific contributions of the research

based on NLSY79 schooling data. Instead, this article demonstrates why the schooling data has played such an important

role in making the NLSY79 one of the premiere research instruments in the social sciences.

Notes

1

 Education alone yields 1,600 matches, schooling alone 588, with

385 matches using both. A search for the words “earnings” or “wages”

yielded 1,437 matches, and for “income,” 1,027 matches. All of these figures are somewhat overstatements because of duplications that arise when

papers appear in multiple forms, for example, as a working paper and later

as a journal publication.

2

 When referring to the NLSY79, I include the Children of the NLSY79.

Recall also that the NLS consists of five additional cohorts, four begun

between 1966 and 1968, and the latest begun in 1997.

3

 I thank Terry Fahey at the Center for Human Resource Research

(CHRR) for performing the specialized search of the Bibliography’s data-
20

NLSY79 Education Data

Monthly Labor Review February 2005

base on which these figures are based.

4

 This is the only psychology journal publishing at least five such articles. There are about a dozen other psychology journals that have published fewer than five, though most have published only one article.

5

 In the NLSY97, on the other hand, the schooling section contained

several hundred questions in the first round. Schooling data in the 1997

survey are obtained as a dated event history similar to the employment

data.

6

 The Current Population Survey (CPS) counts both those with a GED

and those with a regular diploma as a high school graduate.

7

 The samples for the earnings and welfare statistics are both based on

respondent-years in which there is no missing information either on

earnings or on welfare benefits. In addition, the sample is restricted to

those who had at least one report in each 5-year age interval.

8

 As with earnings and welfare, the sample is restricted to those who

have a valid report in at least 1 year of each 5-year age interval.

9

 Financial assets consist of moneys in savings or checking accounts,

money market funds, credit unions, U.S. savings bonds, individual retirement accounts, 401K or pre-tax annuities, certificates of deposits, personal loans to others or mortgages held, stocks, bonds, mutual funds, and

rights to an estate or investment trust.

10 The sample is based on respondent-years in which there is no missing information on the health limitation question. The average numbers of

years over the 25–39 age range in which these data are reported for each

schooling category are: 10.3, 10.0, 10.5, 10.4, and 10.3 for males, and

10.9, 10.6, 10.7, 10.8, and 10.7 for females.

11 More specifically, the 1985 height report was used whenever available (about 90 percent of the cases). If that was missing, the 1982 height

report was used, and if both were missing, the 1981 height report was

used. Differences in reported height in the 3 years are small; mean reported height in 1981 is .17 inches less than in 1985 for those that report

both. The BMI is defined as weight in kilograms divided by the square of

height in meters. Obesity is defined as having a BMI of 30 or more.

12 Information was also collected on maternal behaviors during each

pregnancy, such as prenatal care, smoking, drug use, and drinking.

13 Looking at first-born children avoids differences that might arise if

birth weight is related to birth order, given that less educated women have

more children as shown above. A similar comment applies to the Peabody

Picture Vocabulary Test scores addressed in the following section.