NATIONAL CENTER FOR EDUCATION STATISTICS

Statistical Analysis Report April 2001

Postsecondary Education Descriptive Analysis Reports

Credits and Attainment:

Returns to Postsecondary Education

Ten Years After High School

Brian Zucker

Royal Dawson

Human Capital Research Corporation

1735 North Paulina, Suite 412

Chicago, IL 60622

C. Dennis Carroll

Project Officer

National Center for Education Statistics

U.S. Department of Education

Office of Educational Research and Improvement NCES 2001–168
U.S. Department of Education

Rod Paige

Secretary

National Center for Education Statistics

Gary W. Phillips

Acting Commissioner

The National Center for Education Statistics (NCES) is the primary federal entity for collecting, analyzing,

and reporting data related to education in the United States and other nations. It fulfills a congressional

mandate to collect, collate, analyze, and report full and complete statistics on the condition of education in

the United States; conduct and publish reports and specialized analyses of the meaning and significance

of such statistics; assist state and local education agencies in improving their statistical systems; and review and report on education activities in foreign countries.

NCES activities are designed to address high priority education data needs; provide consistent, reliable,

complete, and accurate indicators of education status and trends; and report timely, useful, and high

quality data to the U.S. Department of Education, the Congress, the states, other education policymakers,

practitioners, data users, and the general public.

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variety of audiences. You, as our customer, are the best judge of our success in communicating information effectively. If you have any comments or suggestions about this or any other NCES product or report,

we would like to hear from you. Please direct your comments to:

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April 2001

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Suggested Citation

U.S. Department of Education. National Center for Education Statistics. Credits and Attainment: Returns

to Postsecondary Education Ten Years After High School, NCES 2001–168, by Brian Zucker and Royal

Dawson. Project Officer: C. Dennis Carroll. Washington, DC: 2001.

For ordering information on this report, write:

U.S. Department of Education

ED Pubs

P.O. Box 1398

Jessup, MD 20794-1398

or call toll free 1-877-4ED-PUBS or go to the Internet: http://www.ed.gov/pubs/edpubs.html

Contact:

Aurora D’Amico

(202) 502-7334
iii

Executive Summary

While the advantages of earning a postsecondary education degree—particularly a bachelor’s

degree—are well documented, the literature is less

conclusive about the economic and social impact

of postsecondary education credits apart from degree completion. Different conclusions about the

economic return of a college education reflect different populations and time periods of analysis

with variations in how a student’s background,

education, and labor force experience were defined and measured.

Although there is in general a pronounced

earnings differential for those with and without a

bachelor’s degree, not all non-college bound students or students with some college but no credential fare poorly in the labor market or fail to

acquire highly marketable skills.

Clarifying the economic outcomes of those

with a high school education but no college, and

those with some college but no degree, and understanding the relationship of factors that potentially

affect individual earnings may help to clarify the

alternatives and risks of either not pursuing a postsecondary education, or completing some college

credits in lieu of a degree. In turn, this information

can help guide the strategies and investment decisions of students, educators, and employers.

This analysis examines 16 student characteristics and their association with earnings 10 years

after high school. To facilitate the analysis, these

characteristics are organized around four broad

aspects of experience and background (referred to

as the earnings framework) as shown below.

Demographic and family background

• Race/ethnicity

• Gender

• Family income in 1980

• Parent education attainment in 1980

High school preparation

• Academic preparation

• Extra-curricular involvement

Postsecondary experience

• College aspirations

• Initial type of institution attended

• College GPA

• Vocational versus liberal arts focus

• Depth versus breadth of curriculum

• Timing of entry

• Undergraduate major

• Education attainment

Early work experience

• Employment while in high school

• Early work experience (1983–86)

Attainment and Background

As of 1992, just under 63 percent of all students from the sophomore class of 1980 had at

least some college, and 42 percent (about twothirds of those who attended college) completed a

program leading to a degree or certificate. In other

words, about one in five students (22 percent)

from this cohort attended college but did not complete a program leading to a degree or certificate.

Students with some college were almost evenly

divided into those who completed 15 or fewer
Executive Summary

iv

college credits, those who completed 16 to 40

credits, and those with more than 40 credits.

Students with some college who fall into these

three categories of attainment, varied not only

with respect to credit production, but across a

range of other characteristics as well. In broad

terms, as discussed in this report, students with

some college, particularly those who completed

more than 40 credits, were most similar to students with a bachelor’s degree, while students

who completed 16 to 40 credits were closer in profile to those with an associate’s degree. By contrast, students who completed 15 or fewer credits

resembled those with no college in some instances

and those with an associate’s degree or vocational

certificate in others.

Student attainment was closely related to several aspects of social-demographic background

including, race, gender, family income and parent

attainment. Females, for example, were more

likely than males to attend college, while black,

Hispanic, and American Indian students were less

likely than either white or Asian students to attend

college or complete a bachelor’s degree. In addition, students with a 1980 family income of

$40,000 and above were more than three times as

likely to have completed a bachelor’s degree and

more than four times as likely to have completed a

graduate degree than a student with a family income under $15,000. Similarly, students with a

bachelor’s degree were more than twice as likely

to have come from families where one or both

parents completed a bachelor’s degree while those

with only a high school diploma were more than

six times as likely to come from a family where

neither parent attended college.

Attainment and Earnings

After controlling for academic and labor force

experiences and background characteristics, a

baccalaureate or associate’s degree was shown to

contribute significantly to earnings and the results

were generally consistent with what others have

estimated.1 Based on the ratio of “adjusted mean”

earnings—which take into account the covariance

of other confounding factors—students with a

bachelor’s degree, on average, earned about 23

percent more than students with no college. For

students with an associate’s degree, there was

about a nine percent earnings differential compared with high school graduates. For students

with some college, there appeared to be about a

six to nine percent mean earnings differential over

those with no college (depending on the number of

credits completed), but there was not enough statistical evidence to draw this conclusion. In other

words, after controlling for multiple aspects of

student experience and background, the economic

returns of some college credits apart from degree

completion were negligible—irrespective of the

number of credits completed. The lack of a return

for students with some college (but no degree),

who in particular completed 40 or more credits

suggests that credit production in the absence of a

meaningful integration of courses contributes little

to individual earnings and/or that there are considerable economic gains that can be attributed to the

degree credential itself.

Postsecondary Education Experience

While students with some college, on average,

showed the same level of earnings as students with

no college, there were numerous instances in

which specific aspects of a postsecondary education experience were associated with higher earnings. These include students whose course work

was vocationally (as opposed to general education) focused, students with undergraduate majors

in computer science, health technology, business

 

1See, for example, Kane and Rouse (1993).
Executive Summary

v

and engineering, students who achieved a balance

of breadth versus depth of study in their curriculum, and students who attained a cumulative GPA

of 3.0 or higher. Differences in earnings were also

observed by type of institution first attended, with

students who attended private not-for-profit fouryear institutions compared with those who attended a two-year public. By contrast, there was

no difference in earnings for students who attended a public four-year institutions compared

with those who attended a public two-year institution, controlling for other factors.

In broader terms, the earnings gain associated

with these various characteristics suggest that

postsecondary education curriculum and academic

performance, along with other aspects of the postsecondary education experience, may figure

prominently in the economic returns to a postsecondary education.

Early Work Experience

Apart from attainment and selected aspects of

the college experience, the findings from this

analysis suggest that labor force experience constitutes an important component of the earnings

equation. Based on the findings of the multiple

regression analysis, workforce experience during

high school and during the four years immediately

following high school can contribute significantly

to individual earnings. While this association potentially reflects differences in motivation as well

as experience, the findings nonetheless suggest

that an enriching early work experience may provide students with an important channel for such

motivation, and in effect mitigate some of the

economic disadvantages of not having a college

degree.

As with questions concerning college access,

however, higher rates of unemployment and a

greater likelihood of falling into the bottom third

of the high school job index or the early work index suggest that some students, such as black and

American Indian students (who are less likely to

complete college), may have less access to enriching employment opportunities as well.

In broader terms, the association between education attainment, early employment and earnings

suggest that the greatest gains in individual earnings are most likely to accrue through a combination of work and postsecondary education. And,

while the responsibilities of employment may

compete with educational activities, work experiences in some instances can be mutually facilitating and mutually reinforcing.

Background and Social Mobility

The last set of observations concerns the influences of socioeconomic background and economic

mobility. In combination, several elements of students’ background, including family income and

high school academic preparation were associated

with earnings both directly and indirectly through

an association with higher attainment.

 While the findings from this analysis reaffirm

the central role of education (at both the high

school and postsecondary level) as a vehicle of

social mobility, in actuality, for the sophomore

class of 1980, the earnings distribution of students

10 years after high school remains closely associated with socioeconomic status during high

school. In other words, while education is positively related to individual earnings—irrespective

of socioeconomic background—the direct and indirect effects of family income still constitute a

dominant factor in the formation of an individual’s

earning capacity.
Executive Summary

vi

Nowhere is this impact more clearly illustrated

than with the racial/ethnic background of students.

After controlling for all other characteristics in the

earnings framework, there was no difference in

student earnings by race/ethnicity. While at one

level this finding suggests that something of an

economic parity with respect to race/ethnicity exists in the labor market, it is crucial to recognize

the extent to which this balance is offset by the

overall disparity in attainment for blacks, Hispanics, and American Indians compared with whites

or Asians.2

While observed differences in earnings by

race/ethnicity are more directly attributable to differences in attainment than other factors, the same

cannot be said with respect to gender. Indeed, for

the sophomore class of 1980, females were more

likely to attend college than males and had

equivalent baccalaureate and advanced degree

rates of attainment. At the same time, after con-

 

2For the sophomore class of 1980, blacks, Hispanics, and

American Indians were less than half as likely as white students and less than one-third as likely as Asians to attain a

bachelor’s degree.

trolling for all factors in the model, there remains

a pronounced earnings differential by gender with

an adjusted mean earnings for females that is approximately 18 percent less than for males.

While this disparity may in part be accounted

for by differences in occupational employment—

which was not considered in the earnings framework—this finding nonetheless brings with it a

number of implications including questions about

comparative differences in a college education’s

economic return on investment, and in the level of

college debt that students may ultimately be able

to assume. At the same time, the positive association between attainment and earnings remains,

regardless of gender. Therefore, while economic

parity, by definition, cannot be achieved through

offsets in attainment for those who are otherwise

disadvantaged, attainment nonetheless serves to

mitigate those disparities.
vii

Foreword

This report analyzes the economic returns to a college education for the sophomore class of

1980 10 years after their senior year of high school. The analysis focuses on students with some

postsecondary education credits but no degree and compares the experiences and outcomes of

this group with students with no postsecondary education as well as those with a degree or vocational certificate. The analysis examines 12 characteristics of student background and their association with education attainment and earnings 10 years after high school.

The report uses data from the High School and Beyond Longitudinal Study and the HS&B

Postsecondary Education Transcript (PETS) File. The information provided through these files

was gathered through a nationally representative survey of high school sophomores in 1980 with

several follow-up surveys administered approximately every two years; the last one took place in

1992.

The estimates presented in this report were produced using the NCES Data Analysis System (DAS) for the HS&B: 80/92 survey. The DAS is a microcomputer application that allows

users to specify and generate their own tables and summary statistics. The DAS produces design

adjusted standard errors necessary for testing the statistical significance of differences shown in

the tables. For more information regarding the DAS, readers should consult appendix C of this

report.
viii

Acknowledgments

The authors wish to thank Laura Horn at MPR Associates for her sustained guidance, insightful comments and infinite patience. We are also grateful to a number of other individuals at

MPR Associates for their ongoing assistance in this effort including Robert Fitzgerald, Vicky

Dingler and Shirley He.

The authors also gratefully acknowledge the careful reviews and thoughtful comments provided by the following individuals: Dennis Carroll, Lisa Hudson and Paula Knepper, Andrew

Kolstad and Roslyn Korb of NCES; Elaine Gilby from PES, Kent Phillippe from the American

Association of Community Colleges, Jeff Owings from ESLSD. Finally, we’d like to thank Clifford Adelman for his guidance at the early stages of this report’s development.
ix

Table of Contents

Page

Executive Summary .................................................................................................................. iii

Foreword.................................................................................................................................... vii

Acknowledgments...................................................................................................................... viii

List of Tables ............................................................................................................................. xi

List of Figures............................................................................................................................ xiv

Introduction............................................................................................................................... 1

Report Organization .............................................................................................................. 1

Data and Definitions ................................................................................................................. 5

Subject Population ................................................................................................................ 5

Measuring Student Earnings and Returns to Education........................................................ 6

Student Background ................................................................................................................. 9

Demographic–Social Background and Education Attainment.............................................. 9

Comparative Earnings by Background and Education Attainment....................................... 11

High School Experience............................................................................................................ 13

High School Academic Preparation: Academic Resources Index ........................................ 13

Comparative Earnings by High School Academic Performance........................................... 14

Postsecondary Education Experience...................................................................................... 15

Educational Aspirations ........................................................................................................ 15

Comparative Earnings by Educational Aspirations............................................................... 16

First Institution Attended ...................................................................................................... 16

Comparative Earnings by Initial Institution Attended........................................................... 17

Academic Focus: Vocational Versus General Education or Incidental Courses................... 18

Comparative Earnings by Academic Focus .......................................................................... 20

Program Concentration: Depth Versus Breadth of Curriculum ............................................ 21

Comparative Earnings by Program Concentration................................................................ 23

Grades in College .................................................................................................................. 24

Comparative Earnings by College GPA................................................................................ 24
Table of Contents

x

Page

Early Work Experiences........................................................................................................... 27

Employment While in High School: The High School Job Index ........................................ 27

Comparative Earnings by High School Job Experience........................................................ 28

Early Work Experience: The Early Work Index ................................................................... 28

Comparative Earnings by Early Work Experience................................................................ 29

Controlling for Related Variables ........................................................................................... 33

Summary and Conclusions....................................................................................................... 43

Bibliography .............................................................................................................................. 47

Appendix A—Regression Analysis Control Variables .......................................................... 49

Appendix B—Variable Glossary ............................................................................................. 59

Appendix C—Technical Notes and Methodology .................................................................. 65
xi

List of Tables

Table Page

A Selected 1991 earnings centiles and average earnings of 1980 sophomores who

graduated from high school in 1982, by level of education attainment in 1992, and

gender .............................................................................................................................. 8

1 Percent distribution of 1980 sophomores who graduated from high school in 1982, by

level of education attainment in 1992, by gender, by race/ethnicity, by family income

in 1980, and by parent’s education attainment................................................................ 10

2 Percentage distribution of 1980 sophomores who graduated from high school in 1982,

by parent’s education attainment and by level of education attainment in 1992 ............ 10

3 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982,

by level of education attainment in 1992, by race/ethnicity, by family income in 1980,

by parent’s education attainment, and by gender. ........................................................... 12

4 Percentage distribution of high school academic preparation of 1980 sophomores who

graduated from high school in 1982, by level of education attainment in 1992. ............ 13

5 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982,

by high school academic preparation, by level of education attainment in 1992, and by

gender .............................................................................................................................. 14

6 Percentage distribution of 1980 sophomores who graduated from high school in 1982,

by educational aspirations in 1982, and by level of education attainment in 1992......... 15

7 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982,

by educational aspirations in 1982, by level of education attainment in 1992, and by

gender .............................................................................................................................. 16

8 Percentage distribution of 1980 sophomores who graduated from high school in 1982

and enrolled in postsecondary education, by type and control of first institution

attended, and by level of education attainment in 1992. ................................................. 17

9 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982

and enrolled in postsecondary education, by type and control of first institution

attended, by level of education attainment in 1992, and by gender ................................ 18
List of Tables

xii

Table Page

10 Percentage distribution of 1980 sophomores who graduated from high school in 1982,

by academic focus, and by undergraduate major............................................................. 19

11 Percentage distribution of 1980 sophomores who graduated from high school in 1982

and enrolled in postsecondary education, by undergraduate academic focus and by

level of education attainment in 1992 ............................................................................. 20

12 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982

and enrolled in postsecondary education, by undergraduate academic focus, by level

of education attainment in 1992, and by gender.............................................................. 21

13 Percentage distribution of 1980 sophomores who graduated from high school in

1982 and enrolled in postsecondary education, by breadth of subjects index, by

undergraduate academic focus, and by level of education attainment in 1992 ............... 22

14 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982

and enrolled in postsecondary education, by breadth of subjects index, by level of

education attainment in 1992, and by gender.................................................................. 23

15 Percentage distribution of 1980 sophomores who graduated from high school in 1982

and enrolled in postsecondary education, by cumulative undergraduate GPA and mean

cumulative undergraduate GPA, by type and control of first institution attended, and

by level of education attainment in 1992 ........................................................................ 25

16 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982

and enrolled in postsecondary education, by cumulative undergraduate GPA, by level

of education attainment in 1992, and by gender.............................................................. 26

17 Percentage distribution of 1980 sophomores who graduated from high school in 1982,

by high school job index and by level of education attainment in 1992 ......................... 28

18 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982,

by high school job index, by level of education attainment in 1992 and by gender ....... 29

19 Percentage distribution of 1980 sophomores who graduated from high school in 1982,

by early work experience (1983–86), and by level of education attainment in 1992...... 30

20 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982,

by early work experience (1983–86), by level of education attainment in 1992, and by

gender .............................................................................................................................. 30

21 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982,

and the adjusted mean earnings after taking into account the covariation of the

variables listed in the regression model .......................................................................... 35
List of Tables

xiii

Table Page

22 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982,

and the adjusted mean earnings after taking into account the covariation of the

variables listed in the regression model .......................................................................... 39

Appendix Tables

A1 Percentage distribution of 1980 sophomores who graduated from high school in 1982,

by high school extracurricular experience, and by level of education attainment in

1992................................................................................................................................. 49

A2 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982,

by high school extracurricular experience, by level of education attainment in 1992,

and by gender .................................................................................................................. 50

A3 Percentage distribution of 1980 sophomores who graduated from high school in 1982

and enrolled in postsecondary education, by timing of entry into college, and by level

of education attainment in 1992...................................................................................... 51

A4 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982

and enrolled in postsecondary education, by timing of entry into college, by level of

education attainment in 1992, and by gender.................................................................. 52

A5 Percentage of 1980 sophomores who graduated from high school in 1982 not enrolled

in college in 1991, by level of education attainment in 1992.......................................... 53

A6 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982,

by level of education attainment in 1992, by enrollment in college in 1991, and by

gender .............................................................................................................................. 54

A7 Percentage of 1980 sophomores who graduated from high school in 1982 who worked

less than full-time full-year in 1991, by level of education attainment in 1992.............. 55

A8 Percentage distribution of 1980 sophomores who graduated from high school in 1982,

by level of education attainment in 1992, and by undergraduate major.......................... 56

A9 Average 1991 earnings of 1980 sophomores who graduated from high school in 1982,

by level of education attainment in 1992, and by undergraduate major.......................... 57

C1 Standard errors for table 1: Average 1991 earnings of 1980 sophomores who

graduated from high school in 1982, by level of education attainment in 1992, by

gender, by race/ethnicity, by family income in 1980, and by parent’s education

attainment........................................................................................................................ 67
xiv

List of Figures

Figure Page

1 Variables included in earnings framework...................................................................... 2

2 Summary of findings from regression analysis based on adjusted mean earnings.......... 38
1

Introduction

While the advantages of earning a postsecondary education degree—particularly a bachelor’s degree—are well documented, the literature is less conclusive about the economic and social impact of postsecondary education credits apart from degree completion.1 Different

conclusions regarding the economic return for students who have not completed college reflect

differences in research methodology, different populations and time periods of analysis, and different data sets, with variations in how specific aspects of student background, education, and

labor force experience were defined and measured.

Although there is in general a pronounced earnings differential for those with and without a

bachelor’s degree, not all non-college bound students or students with some college but no credential fare poorly in the labor market or fail to acquire highly marketable skills. Clarifying the

economic outcomes of those with a high school education but no college, and those with some

college but no degree, and understanding the relationship of factors that potentially affect individual earnings may help to clarify the alternatives, opportunities and risks of either not pursuing

a postsecondary education, or completing some college credits in lieu of a degree. In turn, this

information can help guide the strategies and investment decisions of students, educators, and

employers.

Report Organization

Recognizing that individual earnings are potentially associated with multiple factors, this

analysis compares the developmental experiences of the high school sophomore class of 1980

who graduated from high school in 1982. The analysis is based on 16 selected demographic, social, and economic characteristics, and explores the association between these factors and annual

earnings about 10 years after the senior year of high school (i.e., earnings in 1991). Imparted

 

1Kane and Rouse (1993), for example, have found that “returns to a credit at a two-year or four-year college are both positive

and similar: roughly four to seven percent for every 30 (two semesters of) completed credits, and that the certification value of a

degree appears to be small relative to the value of the coursework.” In contrast, Grubb (1995) has found that “short periods of

time in postsecondary education have uncertain effects.” For women, Grubb concludes that students must complete three or more

years of college to achieve significantly higher earnings, while for men, the effects of small amounts of college—less than one

year—are usually too small to be statistically significant and are essentially zero for younger cohorts. Different outcomes reflect

differing approaches by researchers to discern the marginal effects of a postsecondary education while controlling for other confounding factors. Notably, to the extent that certain potential influences have been excluded and those factors are associated with

other characteristics that have been considered, conclusions about the marginal effects may differ.
Introduction

2

through family, school, work, and community, these 16 characteristics represent the primary

ways through which individuals acquire skills, experience, and credentials that contribute to

earnings later in life. In broad terms, this framework is indicative of models of human capital investment and a body of research that began in the early 1960s with Gary Becker and Edward

Denison.2 Figure 1 summarizes these factors within four broad dimensions of student experience

and background.

Figure 1—Variables included in earnings framework*

Demographic and family

background

High school experience

and preparation

Postsecondary

experience

Early work

experience

• Race/ethnicity

• Gender

• Family income in 1980

• Parent education

attainment in 1980

• Academic preparation

• Extra-curricular

involvement

• College aspirations

• Initial type of institution

attended

• College GPA

• Vocational versus liberal

arts focus

• Depth versus breadth of

curriculum

• Timing of entry

• Undergraduate major

• Education attainment

• Employment while in

high school

• Early work experience

(1983–86)

*Definitions for all variables used in the analysis can be found in appendix B—Variable Glossary.

Using this framework, observations were made about the distributions of each characteristic by level of education attainment and its association with earnings. This stage of the analysis

relied primarily on descriptive statistics and serves to introduce each of the variables and the motivation for its inclusion. In the second stage, a series of multiple regression models were constructed to assess the marginal effect of each factor on earnings while controlling for all other

characteristics. In combination, these two methods of analysis were used to explore the following

questions.

Demographic and Family Background

• How do differences in family–demographic background relate to differences in college

participation and education attainment?

• Are certain aspects of family background, such as parent education attainment or family income, associated with comparatively higher student earnings 10 years after high

school?

 

2See, for example, Becker (1964) or Denison (1962).
Introduction

3

High School Experience and Preparation

• How do the high school experiences of students with some college compare with students who have completed an associate’s or bachelor’s degree, or with students who

did not attend college?

• Do students with different levels of high school academic preparation but comparable

levels of education attainment have significantly different earnings later in life?

Postsecondary Experience

• Do students with some college demonstrate substantially different postsecondary education experiences in terms of type of institution attended, grades, or academic focus,

compared with those who complete a bachelor’s or associate’s degree?

• How are various aspects of postsecondary experience such as grades, curriculum, or

type of institution associated with student earnings after college?

• After controlling for other differences in background such as early work experience,

high school preparation and social characteristics, what are the marginal effects of attainment on earnings?

Work Experience

• How do work experiences differ for students with some college, compared with students who completed an associate’s degree or with students who did not attend college?

• To what extent is work experience in the years immediately following high school associated with comparatively higher earnings later in life?
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5

Data and Definitions

The data used in this analysis was based on the High School and Beyond (HS&B) data set

including the Sophomore Fourth Follow-up and the Sophomore Postsecondary Education Transcript Study (PETS). In combination, these two files supported the construction of a series of

measures that were used to represent each of the characteristics considered in the analysis. The

HS&B data set was particularly valuable for capturing information regarding student’s demographic and family background, college aspirations, work experience and earnings. The PETS

data set provided detailed information on high school academic preparation, what postsecondary

courses the 1980 high school sophomores studied, the type of postsecondary institution students

attended, the number of credits and credential(s) earned, and the grades students received.

Subject Population

While this study examines the earnings of young adults at all levels of attainment, students

with some college credits but no degree are a focal point of this analysis. To put the experiences

of these students into perspective, this group is compared throughout with the sample of 1980

sophomores whose formal education ended with high school graduation in 1982, as well as those

students who completed a vocational certificate, associate’s or bachelor’s degree, or higher.

As of 1992, just under 63 percent of all young adults from the sophomore class of 1980 had

at least some postsecondary education, and 42 percent (about two-thirds of those who attended

college) completed a program leading to a degree or certificate (see table 1). In other words,

about one in five students (22 percent) from this cohort attended college but did not complete a

program leading to a degree or certificate.3

Students with some college were almost evenly divided into those who completed 15 or

fewer college credits, those who completed 16 to 40 credits, and those with more than 40 credits.

Nearly all students at the low end of this spectrum completed less than the equivalent of one full

semester of course work, and can generally be characterized as incidental students “whose records consist either of nothing but withdrawals, incompletes, and failures or who take two or three

 

3In this analysis, the student education attainment variable was derived using transcript data from the PETS file where available,

and self-reported education (Hdeg) for all other students.
Data and Definitions

6

courses and then disappear from education.”4 The other end of the spectrum (students who have

completed more than 40 credits) consists largely of students who completed the equivalent of

three or more semesters of course work.

Students with some college who fall into these three categories of attainment, varied not

only with respect to credit production, but across a range of other characteristics as well. In broad

terms, students with some college who completed more than 40 credits were most similar to students with a bachelor’s degree, while students who completed 16 to 40 credits were closer in profile to those with an associate’s degree. By contrast, students who completed 15 or fewer credits

resembled those with no college in some instances and those with an associate’s degree or vocational certificate in others.

Measuring Student Earnings and Returns to Education

While nearly all studies on the returns to a college degree have shown a positive relationship between individual earnings and attainment, they have often varied in their more detailed

findings.5 These differences raise questions, not only about methodology but about the dynamics

of income and how cyclical and structural changes in the economy can alter the economics of a

college education across time and space. Given the variation in conclusions drawn about education’s return on investment, it is particularly important to examine how earnings have been defined and the context in which earnings and attainment have been measured.

In this study, all comparisons of earnings were based on student self-reported annual earnings in 1991 (about 10 years after high school) as reported in the HS&B Fourth Follow-up. These

estimates excluded students with zero earnings, but otherwise represented students at all other

configurations of employment—regardless of type of employment (e.g., self-employed, military,

and civilian) or level of earnings.

Although the HS&B Fourth Follow-up did not include questions about hours of employment or number of weeks worked, students were asked about the total months they worked, in

addition to a series of questions regarding their primary activities in 1991 (e.g., school, work,

travel, etc.). In the absence of information about hours of employment, it is important to recognize that education attainment contributes to higher earnings not only because hourly compensa-

 

4Adelman (1995, 22) For the sophomore class of 1980, 6.7 percent of all students completed 10 or fewer credits or what Clifford

Adelman referred to as the incidental student. For a more complete discussion of the definition of an incidental student, see

Adelman (1995, 22).

5For review, see Boesel (1999).
Data and Definitions

7

tion tends to be higher, but because there is a greater likelihood of full-time/full-year employment.6

Because differences in earnings by level of education attainment tend to increase with a

person’s age, the length of time from high school until earnings were measured can also affect

conclusions about the returns of a college degree.7 While the HS&B Fourth Follow-up is the

most recent data available and provided a 10-year horizon, it is still more than a decade short of

when earnings differentials by level of education attainment tend to peak.

Conclusions about the returns to a college education for the sophomore class of 1980 also

reflect conditions in the labor market for the year in which earnings were examined. With the

first quarter of 1991 still in recession and the balance of the year considered a period of recovery,

individuals with lower levels of education attainment experienced comparatively sharper decreases in real earnings and prolonged spells of unemployment. As a result, the returns to education for students with some college and those with an associate’s degree may have been lower

than would otherwise be concluded if comparisons were made during a period of economic expansion when demand for less educated workers tends to be higher.8

In comparing differences in mean earnings across different populations, it is also important

to recognize that the distribution of earnings may be high skewed. For example, based on CPS

data, mean earnings for males and females employed full-time, year-round are consistently higher

than median earnings with differences that tend to increase with attainment.9 For the HS&B cohort, the distribution in earnings (table A) are moderately skewed as well. As a result, differences

 

6For example, based on March Current Population Survey data, employment population ratios and the percent working full time

year round increases with education attainment. Overall, about 85 percent of the sophomore class of 1980 were employed for all

12 months of 1991. In the multiple regression phase of this study, two control variables are included as surrogates for labor force

activity. These include a dummy variable for students who are concurrently enrolled in college while employed, and a dummy

variable indicating that a student had earnings below the 1991 minimum wage level, or worked less than full-time and/or less

than full year at minimum wage.

7Using the March 97 CPS data, the earnings differential by level of attainment may peak anywhere from age 40 to 44, when

comparing males with an associate’s degree versus no college, 54 to 59, when comparing males with a bachelor’s versus an associate’s degree, and 60 to 64, when comparing males with a master’s versus a bachelor’s degree. In no instance, in absolute or

relative terms, do earnings differentials peak for individuals in the mid-thirties or younger. Most comparisons using longitudinal

data have used a shorter horizon, in part, because longer term data is generally unavailable. Kane and Rouse (1993) and Grubb

(1995), among others, have used a 14 -year horizon (e.g., age 32) to measure economic returns. While extending the horizon may

help reveal the full economic return of a postsecondary education, it also brings with it the disadvantage of moving further from

the labor market conditions that current cohorts are likely to face.

8According to CPS data, from 1989 to 1991, constant dollar earnings fell by 6.1 percent for males age 25 and older with less than

four years of college and by 9.1 percent for females. In contrast, constant dollar earnings fell by 4.8 percent for males with a high

school diploma and 5.7 percent for females, while earnings for males and females with four years of college declined by 1.6 and

1.1 percent respectively—Table P-14 Historical Income Tables—People. Note: the definitions used by the Current Population

Survey to define education attainment (prior to 1992) are not directly comparable to those used in this study.

9See for example Money Income in the United States, 1999 Current Population Reports Consumer Income Series P-60, US Census Bureau.
Data and Definitions

8

Table A—Selected 1991 earnings centiles and average earnings of 1980 sophomores who graduated from high

school in 1982, by level of education attainment in 1992, and gender

High school

or less

Some

college

(0–15

credits)

Some

college

(16–40

credits)

Some

college

(above 40

credits)

Associate’s

degree or

certificate

Bachelor’s

degree

Advanced

degree

Males

Percent centile

 10th $13,624 $11,421 $12,010 $7,900 $11,327 $14,263 $9,691

 25th 18,574 14,870 15,482 14,307 17,413 21,031 18,558

 50th 27,305 22,255 22,010 22,216 23,931 28,582 28,937

 75th 34,871 30,750 27,712 29,180 31,132 37,000 40,272

 90th 42,405 38,918 36,636 39,865 38,386 44,330 45,526

Mean 27,445 24,782 23,835 24,247 24,992 29,728 29,934

Females

Percent centile

 10th 4,208 4,109 5,161 5,558 7,070 8,311 7,596

 25th 9,153 11,151 12,175 11,446 12,604 16,817 14,950

 50th 13,447 17,998 17,693 17,606 18,855 24,250 23,524

 75th 20,669 23,730 23,601 23,049 25,110 30,320 30,212

 90th 26,257 30,666 29,297 28,781 32,396 37,452 39,764

Mean 14,875 18,960 18,431 18,564 20,138 24,150 24,291

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

in mean earnings by level of attainment may in some instances be slightly higher than differences

at the median.

Finally, because the HS&B Fourth Follow-up does not contain geographic information, observed differences in earnings by level of attainment may also reflect differences in cost of living

and compensation from one region to the next. To the extent that a region with comparatively

lower attainment also had comparatively lower compensation (all other factors being equal), the

analysis may overstate the contribution that attainment makes to earnings by failing to control for

such geographic differences.
9

Student Background

Demographic–Social Background and Education Attainment

Demographic and social characteristics including gender, race/ethnicity, family income, and

parent education attainment reflect innumerable differences in a student’s home and community

environment with potential bearing on quality of schooling and access to peers, role models, and

networks of support.10, 11

For the sophomore class of 1980, demographic–social background figures prominently in

the education attainment of students (table 1). Females, for example, were more likely than males

to attend college. Black, Hispanic, and American Indian students were less likely than either

white or Asian students to attend college or complete a bachelor’s degree. Asian students demonstrated the highest overall attainment and were more likely than white students (who had the second highest levels of attainment) to attend college or earn a graduate degree.

Student attainment was also associated with family income; students from moderate income ($15,000 to $24,999) families were more likely to complete a bachelor’s degree than those

from low income families (under $15,000) and students from middle income families ($25,000 to

$40,000) were more likely to complete a bachelor’s degree than those from moderate income

families. For the sophomore class of 1980, a student with a family income of $40,000 and above

was more than three times as likely to have completed a bachelor’s degree and more than four

times as likely to have completed a graduate degree than a student with a family income under

$15,000.

Student education attainment was also closely associated with the attainment of their parents (table 2). For instance, among students with a bachelor’s degree, about half came from

families where one or both parents completed a bachelor’s degree or higher compared with

 

10Numerous studies have examined socio-economic status and its relationship to attainment and earnings. For a capsule review,

see, for example, Pascarella and Terenzini (1991, 524–525).

11This analysis used three categories of parent attainment: (1) neither parent has attended college; (2) one or both parents have

attended college and have completed up to an associate’s degree or a vocational certificate but less than a bachelor’s degree; and

(3) one or both parents have earned at least a bachelor’s degree. A more complete discussion of the parent education attainment

variable is given in the appendix.
Student Background

10

Table 1Percent distribution of 1980 sophomores who graduated from high school in 1982, by level of education attainment in 1992, by gender, by race/ethnicity, by family income in 1980, and by parent’s

education attainment

High

school

or less

Some

college

(0–15

credits)

Some

college

(16–40

credits)

Some

college

(above

40 credits)

Associate’s

degree or

certificate

Bachelor’s

degree

Advanced

degree

 Total 37.1 7.0 7.9 6.6 14.3 19.0 8.2

Gender

 Male 40.6 6.1 7.8 6.4 12.2 18.7 8.1

 Female 33.6 7.9 7.9 6.9 16.2 19.3 8.2

Race/ethnicity

 White 34.2 6.9 7.5 6.2 14.5 21.4 9.3

 Black 45.3 7.6 9.5 9.7 13.6 10.6 3.7

 Hispanic 51.6 7.6 8.4 6.3 14.5 8.3 3.3

 Asian or Pacific Islander 17.6 4.6 6.3 10.5 10.9 30.2 19.9

 Native American 49.6 9.2 14.5 5.5 11.2 9.0 1.1

Family income in 1980

 $0–14,999 47.0 7.3 9.6 7.0 13.9 11.3 3.9

 $15,000–24,999 32.6 7.2 9.0 6.1 18.8 18.9 7.5

 $25,000–39,999 26.6 7.4 8.2 7.4 14.7 25.7 10.0

 $40,000 or more 18.4 6.1 6.6 10.0 11.7 30.2 17.0

Parent education attainment

 No college 51.4 6.5 6.2 4.5 19.4 9.5 2.6

 Some college/associate’s degree 29.6 6.7 7.4 7.8 22.4 18.9 6.9

 Bachelor’s degree or higher 14.2 4.6 5.3 7.9 15.1 35.7 17.2

NOTE: Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal Study of

1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

Table 2—Percentage distribution of 1980 sophomores who graduated from high school in 1982, by parent’s

education attainment and by level of education attainment in 1992

Neither parent

attended college

One or both parents have

an associate’s degree or

some college

One or both parents have

a bachelor’s

degree or higher

High school diploma only 65.7 24.2 10.1

Enrolled in any postsecondary education total 32.7 31.6 35.8

 Some college (0–15 credits) 47.1 32.8 20.1

 Some college (16–40 credits) 45.0 34.6 20.5

 Some college (above 40 credits) 32.3 35.2 32.5

 Students with some college total 41.6 34.2 24.2

 Associate’s degree or certificate 43.2 34.8 22.0

 Bachelor’s degree 22.5 28.4 49.1

 Advanced degree 15.5 26.8 57.8

NOTE: Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal Study of

1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Student Background

11

slightly more than one in five for students with parents who did not attend college (table 2). By

contrast, among students with no college, nearly two-thirds came from families where neither

parent attended college while one in ten came from families where one or both parents completed

a bachelor’s degree or higher.

Among students with some college, the likelihood of coming from a family where one or

both parents had a bachelor’s degree was greater for students with more than 40 credits. In general, parents of students with less than 40 credits had similar educational attainment to parents of

students with an associate’s degree. While parent attainment for students with more than 40

credits was higher than those with fewer credits or an associate’s degree, but still below the parental attainment of those students who completed a bachelor’s degree or higher.

Comparative Earnings by Background and Education Attainment

For the sophomore class of 1980, males and females with a bachelor’s degree had higher

earnings than students with lower levels of attainment (table 3).12 At the sub-baccalaureate level,

the returns to education were less conclusive. Males with some college, for example, had the

same earnings as males with no college—regardless of the number of credits completed, while

females with some college had higher earnings than those with no college. At the same time,

males and females with some college had the same earnings as students with an associate’s degree.

In certain instances, after considering education attainment, earnings also differed by

race/ethnicity. Black males with a graduate degree, for example, had lower earnings than their

Asian counterparts, while black males with no college had lower earnings than their white counterparts.

Apart from the indirect influence that family background brings to earnings through attainment, there is a direct association as well. For example, males and females from families with

incomes of $25,000 and above who did not attend college had higher earnings than students with

no college from families with incomes under $15,000. Similarly, males with a bachelor’s degree

from families with incomes of $40,000 and above had higher earnings than males with a bachelor’s from families with incomes under $15,000.

 

12There was no difference in earnings for males or females with a graduate degree compared with those who have earned a

bachelor’s degree (.17) (.15). In part, this similarity may be a function of time out from college. For students who have completed

a graduate degree, even under timely completion, the average master’s degree holder would have been “in the field” less than five

years.
Student Background

12

Table 3—Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, by level of

education attainment in 1992, by race/ethnicity, by family income in 1980, by parent’s education attainment, and by gender

High

school

or less

Some

college

(0–15

credits)

Some

college

(16–40

credits)

Some

college

(above 40

credits)

Associate’s

degree or

certificate

Bachelor’s

degree

Advanced

degree

Males

 Total $21,769 $24,782 $23,835 $24,247 $24,992 $29,728 $29,934

Race/ethnicity

 White 22,699 25,836 24,837 24,349 25,053 30,001 29,902

 Black 18,397 — 19,719 22,325 23,286 26,061 25,972

 Hispanic 20,362 23,401 23,521 21,772 27,758 29,831 26,352

 Asian or Pacific Islander ————— 31,542 38,555

 Native Americans ———————

Family income in 1980

 $0–14,999 19,147 19,294 21,773 23,374 23,217 27,893 21,205

 $15,000–24,999 21,941 23,458 22,111 20,062 24,493 29,353 29,839

 $25,000–39,999 23,865 24,869 25,986 22,674 24,352 29,020 27,308

 $40,000 or more 28,307 33,264 27,013 31,512 28,363 32,224 33,249

Parent’s education attainment

 No college 21,931 23,311 24,018 22,446 25,085 29,260 28,773

 Some college/associate’s degree 22,549 23,328 22,550 26,394 24,765 29,550 29,329

 Bachelor’s degree or higher 22,669 28,110 27,310 23,070 24,675 30,133 30,968

Females

 Total 14,256 18,960 18,431 18,564 20,138 24,150 24,291

Race/ethnicity

 White 14,357 18,353 18,193 18,879 20,539 23,864 24,126

 Black 14,850 21,435 22,201 16,877 18,130 22,743 23,001

 Hispanic 13,107 19,720 15,855 20,658 19,159 24,725 28,230

 Asian or Pacific Islander ————— 27,322 27,270

 Native American ———————

Family income in 1980

 $0–14,999 13,293 17,087 17,921 17,295 16,846 22,275 25,295

 $15,000–24,999 13,779 17,584 16,705 18,958 20,921 23,017 21,271

 $25,000–39,999 16,407 18,993 18,870 18,286 22,606 24,877 25,692

 $40,000 or more 17,184 — 21,424 17,386 20,545 25,654 23,835

Parent’s education attainment

 No college 13,578 17,616 16,360 18,402 19,989 22,465 25,735

 Some college/associate’s degree 15,799 19,989 20,257 18,312 18,894 24,692 22,783

 Bachelor’s degree or higher 16,796 19,524 18,393 16,287 22,929 25,093 24,526

—Sample size too small for reliable estimate.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
13

High School Experience

High School Academic Preparation: Academic Resources Index

To help understand the relationship between high school academic preparation and attainment and earnings later in life, this analysis employed a variable constructed by Adelman referred to as the Academic Resources Index. The index, (which is based on four criteria: intensity

of the high school academic curriculum, high school class rank, high school GPA, and students’

score on a composite aptitude test “that can be described as a mini, enhanced SAT”13) is indicative of type of rating systems many colleges employ to assess the desirability of admission candidates and to predict a student’s capacity to perform in college.

For the sophomore class of 1980, the academic resource index was strongly associated with

persistence (as measured by credit production) and attainment. Students who completed a

bachelor’s degree were more than four times as likely to fall in the top fifth of the index than students at lower levels of attainment (table 4), while students with no college were the most likely

to fall in the bottom fifth of the index.

Table 4Percentage distribution of high school academic preparation of 1980 sophomores who graduated

from high school in 1982, by level of education attainment in 1992

Bottom 20 percent of

academic resource index

Middle 60 percent of

academic resource index

Top 20 percent of

academic resource index

High school diploma only 42.6 55.6 1.8

Enrolled in any postsecondary education total 9.8 60.3 29.9

 Some college (0–15 credits) 24.2 70.5 5.3

 Some college (16–40 credits) 16.8 73.7 9.5

 Some college (above 40 credits) 9.5 69.9 20.6

 Students with some college total 16.7 71.5 11.9

 Associate’s degree or certificate 16.9 73.4 9.8

 Bachelor’s degree 1.5 49.8 48.7

 Advanced degree 0.3 35.9 63.8

NOTE: Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal Study of

1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

 

13Based on the distribution of index scores, students were grouped into one of three categories: the top 20 percent, the middle 60

percent, and the bottom 20 percent. For a full discussion concerning the development of the academic resource index see Adelman (1999).
High School Experience

14

Comparative Earnings by High School Academic Performance

High school academic preparation was associated with earnings for students at several different levels of attainment. Male and female students who completed a bachelor’s degree and fell

in the top fifth of the academic resource index had higher earnings than their male and female

counterparts who fell in the middle 60 percent of the index (table 5). Similarly, male students

with some college who completed 16 to 40 credits and fell in the middle 60 percent of the index

had higher earnings than students with the same attainment who fell in the bottom 20 percent of

the index.14

Table 5Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, by high school

academic preparation, by level of education attainment in 1992, and by gender

Bottom 20 percent of

academic resource index

Middle 60 percent of

academic resource index

Top 20 percent of

academic resource index

Males

High school diploma only $20,748 $22,868 —

Enrolled in any postsecondary education total 21,794 25,872 $30,287

 Some college (0–15 credits) 18,807 26,679 —

 Some college (16–40 credits) 20,329 24,883 23,284

 Some college (above 40 credits) — 26,266 21,290

 Associate’s degree or certificate 25,748 23,875 28,298

 Bachelor’s degree — 27,495 32,328

 Advanced degree — 26,278 30,941

Females

High school diploma only 14,814 14,360 —

Enrolled in any postsecondary education total 18,834 20,183 25,070

 Some college (0–15 credits) 18,428 17,834 —

 Some college (16–40 credits) 16,744 18,127 —

 Some college (above 40 credits) — 17,964 17,792

 Associate’s degree or certificate 17,947 20,661 20,601

 Bachelor’s degree — 22,317 26,204

 Advanced degree — 20,956 26,208

—Sample size too small for reliable estimate.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

 

14In most cases, it was not possible to compare differences in earnings for students in the top and bottom 20 percent of the academic resource index due to insufficient sample size.
15

Postsecondary Education Experience

In this section of the analysis, five aspects of postsecondary experience were considered for

their possible association with attainment and earnings including college aspirations, type of institution attended, academic focus (liberal arts versus vocational), depth versus breadth of curriculum and grades.15

Educational Aspirations

Educational aspirations are not only a measure of students’ motivation to attend college,

but potentially of career motivation as well. Aspirations may also reflect differences in academic

preparation, family background, or choice of institution as well as career interests. For the

sophomore class of 1980, educational attainment was closely associated with aspirations. Students with the highest attainment (i.e., graduate degrees) reported the highest aspirations, while

those with the lowest attainment (high school or less) reported the lowest aspirations (table 6).

Table 6Percentage distribution of 1980 sophomores who graduated from high school in 1982, by educational aspirations in 1982, and by level of education attainment in 1992

Educational aspirations in 1982

High school

graduate

or less

Two years

or less of

vocational

Less than

four years

of college

Bachelor’s

degree

Advanced

degree

High school diploma only 51.4 27.8 12.2 5.4 3.2

Enrolled in any postsecondary education total 10.4 13.9 19.7 29.8 26.1

 Some college (0–15 credits) 18.7 28.5 26.2 16.4 10.2

 Some college (16–40 credits) 7.9 21.2 29.2 25.4 16.3

 Some college (above 40 credits) 4.7 12.2 19.3 36.2 27.7

 Students with some college total 10.3 20.7 25.0 26.0 18.0

 Associate’s degree or certificate 10.4 30.4 31.3 15.8 12.2

 Bachelor’s degree 0.7 2.9 14.1 44.9 37.4

 Advanced degree 0.3 0.6 8.0 38.4 52.7

NOTE: Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

 

15Pascarella and Terenzini (1991) devote a chapter to the subject of economic returns with particular attention to so-called between- and within-college effects. For a more recent example of how institutional characteristics have been treated, see Hoxby

and Long (1999).
Postsecondary Education Experience

16

Comparative Earnings by Educational Aspirations

For students with comparable attainment, there was generally no association between

earnings and aspirations. (table 7). One difference of note, however, was found among males

with a bachelor’s who did not aspire to attend college—and had lower earnings than males with

the same attainment who aspired to a bachelor’s or graduate degree.

Table 7Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, by educational

aspirations in 1982, by level of education attainment in 1992, and by gender

Educational aspirations in 1982

High school

graduate

or less

Two years

or less of

vocational

Less than

four years

of college

Bachelor’s

degree

Advanced

degree

Males

High school diploma only $21,577 $21,140 $24,521 $21,882 $24,850

Enrolled in any postsecondary education total 23,025 24,337 25,309 28,275 29,704

 Some college (0–15 credits) 28,305 27,197 21,479 23,486 19,014

 Some college (16–40 credits) 22,488 21,670 23,802 26,075 27,019

 Some college (above 40 credits) 18,815 23,255 27,409 23,535 26,045

 Associate’s degree or certificate 23,018 25,084 25,461 26,973 23,993

 Bachelor’s degree 18,256 — 26,466 30,381 32,113

 Advanced degree ——— 30,172 30,912

Females

High school diploma only total 12,997 15,313 16,261 16,432 17,111

Enrolled in any postsecondary education total 18,131 18,431 21,035 22,315 23,501

 Some college (0–15 credits) 16,886 22,008 20,374 15,600 —

 Some college (16–40 credits) 16,443 16,902 16,331 22,047 19,826

 Some college (above 40 credits) — — 17,037 18,688 17,876

 Associate’s degree or certificate 21,700 17,538 21,717 20,071 21,233

 Bachelor’s degree — — 24,771 23,950 25,633

 Advanced degree — — 26,153 23,223 24,562

—Sample size too small for reliable estimate.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

First Institution Attended

The type of postsecondary institution (level of educational offerings and control) students

initially attend potentially reflect differences in curriculum as well as differences in the provision

of learning resources (such as instruction, advising, remedial support, or facilities) any or all of

which may contribute to attainment and earnings.
Postsecondary Education Experience

17

Type of institution is also relevant because certain institutional categories account for a disproportionate share of all non-completers (students who leave a postsecondary institution without

attaining a degree or certificate). For the sophomore class of 1980, public two-year colleges represented 40 percent of all students who attended college but nearly 60 percent of all students with

college credits but no degree (table 8).

Table 8Percentage distribution of 1980 sophomores who graduated from high school in 1982 and enrolled

in postsecondary education, by type and control of first institution attended, and by level of education attainment in 1992

Public

two-year

or less

Public

four-year

Private,

not-forprofit

less than

four-year

Private,

not-forprofit

four-year

Private

for-profit

two-year

or less

Private

for-profit

four-year

 Total 40.0 35.1 2.1 16.6 5.7 0.5

Education attainment

 Some college (0–15 credits) 74.8 15.8 1.9 4.6 3.0 0.1

 Some college (16–40 credits) 59.8 26.2 1.6 7.5 4.9 0.0

 Some college (above 40 credits) 36.5 42.8 2.6 14.9 1.8 1.2

 Students with some college total 57.6 27.9 2.0 8.8 3.3 0.4

 Associate’s degree or certificate 59.6 11.9 4.7 3.9 19.1 0.8

 Bachelor’s degree 18.0 52.9 0.9 27.2 0.7 0.3

 Advanced degree 10.4 53.6 0.5 34.9 0.2 0.4

NOTE: Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

At the same time the number of credits completed by students with some college varied by

type of initial institution. Students who earned 15 or fewer credits, were more likely to have attended a public two-year institution than students who completed more than 40 credits, and students with more than 40 credits were more likely to have attended a public four-year institution

or private, not-for-profit four-year institution than those with fewer credits.

Comparative Earnings by Initial Institution Attended

For students with comparable attainment, there was generally no association between

earnings and type of institution attended (table 9). While students with comparable attainment, in

general, had comparable earnings, males and females who began college at a public two-year

public college and subsequently completed a bachelor’s degree (e.g., students who transferred to

a four-year college) had lower earnings than students with a bachelor’s degree who began college

at a four-year institution.
Postsecondary Education Experience

18

Table 9Average 1991 earnings of 1980 sophomores who graduated from high school in 1982 and enrolled

in postsecondary education, by type and control of first institution attended, by level of education

attainment in 1992, and by gender

Public two-year

or less

Public

four-year

Private,

not-for-profit four-year

Males

 Total $24,717 $28,512 $29,702

Education attainment

 Some college (0–15 credits) 26,080 23,244 —

 Some college (16–40 credits) 22,455 26,345 —

 Some college (above 40 credits) 26,217 22,344 27,905

 Associate’s degree or certificate 24,211 27,419 —

 Bachelor’s degree 26,075 30,574 31,200

 Advanced degree 25,064 30,392 30,543

Females

 Total 19,795 22,809 23,754

Education attainment

 Some college (0–15 credits) 19,528 17,817 —

 Some college (16–40 credits) 19,596 17,841 14,303

 Some college (above 40 credits) 17,864 19,556 19,097

 Associate’s degree or certificate 20,142 22,321 17,753

 Bachelor’s degree 20,387 24,840 24,434

 Advanced degree 21,190 22,883 28,028

—Sample size too small for reliable estimate.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

Academic Focus: Vocational Versus General Education or Incidental Courses

To help understand the association between course content, attainment, and earnings, an

academic focus variable was constructed that classified students based on whether the majority of

credits they completed were vocational, general education, or recreational/incidental in nature.

Because this variable was constructed at the course level, it was possible for students to have

majored in a subject generally regarded as nonvocational (e.g., history) but still have completed a

majority of their credits in courses that were classified as vocational (e.g., computer programming). As a result, nearly all fields of study included students from all three classifications. To

illustrate, table 10 shows the distribution of students by academic major and academic focus.16

 

16A detailed discussion of the construction of the academic focus variable is given in appendix B (see “Acfocus”).
Postsecondary Education Experience

19

Table 10Percentage distribution of 1980 sophomores who graduated from high school in 1982, by academic

focus, and by undergraduate major

Vocational

focus

General education

focus

Incidental

focus

 Total 36.2 62.9 1.0

Undergraduate major

 Clerical and office administration 82.2 16.8 1.1

 Architecture or environmental design 24.5 75.5 0.0

 Film, fine and performing art 5.9 93.0 1.0

 Biological sciences 8.8 90.9 0.3

 Business administration and management 42.4 55.4 2.3

 Communications 18.1 81.3 0.6

 Communication technology ———

 Computer and information science 51.5 47.5 1.0

 Consumer services 79.9 15.6 4.5

 Graphic or industrial design 6.4 93.6 0.0

 Textiles/fashion ———

 Education 1.9 95.9 2.2

 English or American literature 2.7 95.9 1.4

 Engineering 61.7 37.8 0.5

 Allied health: general and other 34.5 63.0 2.5

 Dentistry, medicine and nursing 20.1 79.5 0.3

 Health related technicians 48.8 49.5 1.6

 Home economics 52.2 47.8 0.0

 Foreign language 1.2 98.3 0.5

 Law 9.2 90.8 0.0

 Liberal or general studies 12.9 86.2 1.0

 Library or archival science ———

 Mathematics 4.3 95.7 0.0

 Marketing and distribution 66.7 32.2 1.2

 Agriculture and resource management 54.4 45.7 0.0

 Philosophy 0.2 99.8 0.0

 Physical science 8.5 88.4 3.1

 Precision production 85.3 14.3 0.4

 Protective services 7.2 92.0 0.8

 Social work or social service 3.8 96.2 0.0

 Social science 0.8 98.0 1.3

—Sample size too small for reliable estimate.

NOTE: Academic focus was created for this study as a curriculum content variable based on which of the three course categories:

vocational (such as hotel management or plumbing), general education (such as biology, social sciences or literature); or incidental (such as Yoga or varsity athletics) accounted for the largest share of credits earned. For a more complete discussion of

academic focus see appendix B variable glossary.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Postsecondary Education Experience

20

There were some associations between education attainment and academic focus. For example, students with some college who completed 15 or fewer credits, and students with an associate’s degree were more likely than students at other levels of attainment to have had a

vocationally oriented curriculum (table 11). Students with some college who completed 40 or

more credits and students with a bachelor’s or graduate degree were more likely than those with

an associate’s degree or those with 15 or fewer credits to have had a general education focus.

Table 11Percentage distribution of 1980 sophomores who graduated from high school in 1982 and enrolled

in postsecondary education, by undergraduate academic focus and by level of education attainment in 1992

Vocational

focus*

General education

focus*

Incidental

focus*

 Total 36.2 62.9 1.0

Education attainment

 Some college (0–15 credits) 46.1 52.1 1.8

 Some college (16–40 credits) 27.0 70.5 2.6

 Some college (above 40 credits) 18.2 81.5 0.3

 Students with some college total 30.5 67.9 1.6

 Associate’s degree or certificate 66.9 32.7 0.4

 Bachelor’s degree 25.0 74.0 1.0

 Advanced degree 23.6 76.1 0.4

*Based on the dominant number of courses student completed.

NOTE: Academic focus was created for this study as a curriculum content variable based on which of the three course categories:

vocational (such as hotel management or plumbing), general education (such as biology, social sciences or literature); or incidental (such as Yoga or varsity athletics) accounted for the largest share of credits earned. For a more complete discussion of

academic focus see appendix B variable glossary. Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

Comparative Earnings by Academic Focus

While average earnings varied by academic focus, these differences were not consistent

across levels of attainment. Among students with some college who completed more than 40

credits, males with a general education focus had higher earnings than males with a vocational

focus (table 12). In contrast, among students with a bachelor’s or graduate degree, males with a

vocational focus had higher earnings than males with a general education focus. Finally, despite

the strong vocational orientation typically associated with two-year programs, there was no difference in earnings by academic focus for males or females with an associate’s degree.17

 

17For female students with comparable levels of education attainment, there was no significant difference in earnings by academic focus (1.64, .65, 1.08, .76, .11, 1.59).
Postsecondary Education Experience

21

Table 12Average 1991 earnings of 1980 sophomores who graduated from high school in 1982 and enrolled

in postsecondary education, by undergraduate academic focus, by level of education attainment in

1992, and by gender

Vocational focus General education focus

Males

 Total $27,979 $26,409

Education attainment

 Some college (0–15 credits) 28,295 21,743

 Some college (16–40 credits) 21,882 25,142

 Some college (above 40 credits) 19,911 25,085

 Associate’s degree or certificate 25,054 24,982

 Bachelor’s degree 31,664 28,844

 Advanced degree 36,657 26,877

Females

 Total 21,239 21,709

Education attainment

 Some college (0–15 credits) 21,145 16,863

 Some college (16–40 credits) 17,573 18,788

 Some college (above 40 credits) 16,934 19,097

 Associate’s degree or certificate 20,500 19,493

 Bachelor’s degree 24,120 24,243

 Advanced degree 26,961 23,706

NOTE: Academic focus was created for this study as a curriculum content variable based on which of the three course categories:

vocational (such as hotel management or plumbing), general education (such as biology, social sciences or literature); or incidental (such as Yoga or varsity athletics) accounted for the largest share of credits earned. For a more complete discussion of

academic focus see appendix B variable glossary.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

Program Concentration: Depth Versus Breadth of Curriculum

While undergraduate curricula are designed to achieve both breadth of knowledge and

mastery in a particular subject,18 students normally exercise considerable latitude in the selection

of individual courses (table 13). As a result, most students face a tradeoff concerning the “depth

versus breadth” of their curriculum with potential bearing on earnings later in life. On the one

hand, too much specialization may fail to prepare students with the capacity to adapt to labor

market demands outside their immediate knowledge. On the other hand, too much breadth may

come at the expense of acquiring the necessary skills and knowledge required for entry into a

specific field of employment.

 

18See, for example, An Overview of Accreditation on North Central Association Commission on Institutions of Higher Education’s website—www.ncacihe.org.
Postsecondary Education Experience

22

Table 13Percentage distribution of 1980 sophomores who graduated from high school in 1982 and enrolled

in postsecondary education, by breadth of subjects index, by undergraduate academic focus, and

by level of education attainment in 1992

Breadth of subjects index Mean index

Four or less Five to six Seven to eight Nine or more score

 Total 48.0 15.0 31.3 5.7 5.7

Vocational focus

Education attainment

 Some college (0–15 credits) 74.8 19.7 5.6 0.0 4.3

 Some college (16–40 credits) 51.7 37.9 7.9 2.5 5.0

 Some college (above 40 credits) 38.8 34.7 21.6 4.9 5.4

 Associate’s degree 49.9 29.9 16.6 3.6 5.1

 Bachelor’s degree 43.0 31.4 15.3 10.3 5.5

 Advanced degree 49.9 32.7 13.4 4.3 5.0

General education focus

Education attainment

 Some college (0–15 credits) 63.9 25.6 10.2 0.3 4.6

 Some college (16–40 credits) 28.9 34.9 27.4 8.8 6.0

 Some college (above 40 credits) 3.4 16.7 30.8 49.2 8.8

 Associate’s degree 13.1 21.7 25.0 40.2 7.7

 Bachelor’s degree 10.8 21.2 31.4 36.7 7.8

 Advanced degree 19.3 27.6 23.0 30.1 7.0

NOTE: Breadth of the subjects studied was based on the concentration of courses completed across the range of course offerings

by CIP code. Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

To help explore the relationship between depth versus breadth of curriculum and attainment

and earnings, a concentration index was constructed to measure the dispersal of courses students

completed by academic subject. The index was based on an algorithm known as the Hirschman–

Herfindahl concentration index, which has been used in numerous other applications from measuring racial segregation to industrial concentration.19

The values generated by this index represent an equivalency of the number of subjects

studied at the undergraduate level and range from an index score of 1, which would indicate that

all coursework was taken within a single subject area, to a score of N which would indicate a

breadth of coursework equivalent to the total number of subjects offered.

On average, students studied the equivalent of about six subjects as undergraduates. With

the exception of students who completed fifteen or fewer credits, students with a general educa-

 

19For a brief overview, see Bannock, Baxter, and Rees (1972).
Postsecondary Education Experience

23

tion focus studied a greater breadth of subjects than students with a vocational focus. In addition,

among students who had a general education focus, those with some college who completed

more than 40 credits studied a greater breadth of subjects than students who completed a bachelor’s or advanced degree.20

Comparative Earnings by Program Concentration

Although program concentration in several instances was associated with differences in

earnings, these differences were not consistent across levels of attainment or by gender (table

14). For instance, among students with a bachelor’s degree, males in the middle bands of the

Table 14Average 1991 earnings of 1980 sophomores who graduated from high school in 1982 and enrolled

in postsecondary education, by breadth of subjects index, by level of education attainment in 1992,

and by gender

Breadth of subjects index

Four or less Five to six Seven to eight Nine or more

Males

 Total $27,823 $27,368 $28,365 $26,170

Education attainment

 Some college (0–15 credits) 23,254 ———

 Some college (16–40 credits) 23,252 21,461 26,450 —

 Some college (above 40 credits) — 23,743 23,653 26,935

 Associate’s degree 25,836 21,791 27,298 25,055

 Bachelor’s degree 29,235 31,142 31,892 26,455

 Advanced degree 35,553 31,573 28,186 24,188

Females

 Total 21,140 23,666 23,270 20,325

Education attainment

 Some college (0–15 credits) 16,536 ———

 Some college (16–40 credits) 16,350 21,185 16,877 —

 Some college (above 40 credits) — 16,591 23,108 17,113

 Associate’s degree 19,650 22,662 21,402 18,643

 Bachelor’s degree 25,300 24,829 25,397 21,932

 Advanced degree 28,012 26,117 23,967 20,941

—Sample size too small for reliable estimate.

NOTE: Based on the concentration of courses completed across range of CIP course categories.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

 

20In part, this dispersal of courses may help explain why some students at this level of attainment may have failed to complete a

degree program despite a demonstrated capacity to perform academically.
Postsecondary Education Experience

24

index (the equivalent of five to eight subjects) had higher earnings than males in the top band

(nine or more subjects). By contrast, among students with an advanced degree, males in the bottom band (the equivalent of four or fewer subjects) had higher earnings than males who studied

the equivalent of seven or eight subjects while females in the bottom band had higher earnings

than females in the top band.

Grades in College

College GPAs represent a fundamental measure of academic performance, reflecting not

only cognitive gains but, more broadly a student’s integration into college life and capacity to

avail themselves of their learning environment. In addition to serving as an effective predictor of

retention and attainment, college grades also serve as an important screening mechanism for additional education or employment.21

For the sophomore class of 1980, students with a graduate or bachelor’s degree had higher

GPAs than did students at lower levels of attainment (table 15). Similarly, students from twoand four-year public institutions with an associate’s degree (on average) had higher GPAs than

students with some college but no degree.

At public four-year institutions, about one-third of all students with 15 or fewer credits had

GPAs of 2.0 or higher, compared with about 80 percent of all students with an associate’s degree

and more than 95 percent of all students with a bachelor’s degree. There appeared to be the same

pattern with private, not-for-profit four-year institutions, but the only significant difference was

between students with 15 or fewer credits and those with a bachelor’s degree.

Comparative Earnings by College GPA

With the exception of students with a bachelor’s degree, undergraduate GPAs were not associated with earnings (table 16). For students with a bachelor’s degree, however, males with a

GPA of less than 2.0 had lower earnings than males with a GPA of 2.0 or higher. Similarly females with a bachelor’s degree and a GPA of between 2.0 and 2.99 had lower earnings than females with a GPA of 3.0 or higher.

 

21In this analysis, students were grouped into four categories of undergraduate GPAs for all students. To allow for potential differences in grading standards across different types of institutions, the distribution of GPA scores were tabulated separately by

educational sector of initial institution.
Postsecondary Education Experience

25

Table 15Percentage distribution of 1980 sophomores who graduated from high school in 1982 and enrolled

in postsecondary education, by cumulative undergraduate GPA and mean cumulative undergraduate GPA, by type and control of first institution attended, and by level of education attainment in 1992

GPA

less than 2.0

GPA

2.0 to 2.49

GPA

2.5 to 2.99

GPA

3.0 and above

Mean

GPA

 Total 16.2 19.7 28.8 35.3 2.62

Public 2-year

Education attainment

 Some college (0–15 credits) 36.5 17.0 14.4 32.1 2.27

 Some college (16–40 credits) 26.8 24.6 24.3 24.3 2.39

 Some college (above 40 credits) 22.5 26.9 29.9 20.7 2.47

 Associate’s degree 12.4 23.3 27.6 36.8 2.64

 Bachelor’s degree 2.1 20.1 37.3 40.5 2.83

 Advanced degree 0.0 6.5 37.1 56.4 3.04

Public 4-year

Education attainment

 Some college (0–15 credits) 63.9 18.2 3.7 14.2 1.63

 Some college (16–40 credits) 51.0 24.7 13.6 10.7 1.99

 Some college (above 40 credits) 37.0 34.9 20.6 7.5 2.16

 Associate’s degree 20.3 26.0 28.0 25.7 2.49

 Bachelor’s degree 3.0 19.2 40.2 37.6 2.80

 Advanced degree 0.8 6.8 38.5 53.9 3.01

Private, not-for-profit 4-year

Education attainment

 Some college (0–15 credits) 51.8 0.8 1.4 45.9 2.09

 Some college (16–40 credits) 45.3 17.6 19.0 18.1 2.25

 Some college (above 40 credits) 27.6 41.9 14.6 15.9 2.31

 Associate’s degree 19.7 26.3 34.3 19.7 2.46

 Bachelor’s degree 3.6 19.6 38.9 37.9 2.82

 Advanced degree 0.4 2.6 29.5 67.4 3.14

NOTE: Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Postsecondary Education Experience

26

Table 16Average 1991 earnings of 1980 sophomores who graduated from high school in 1982 and enrolled

in postsecondary education, by cumulative undergraduate GPA, by level of education attainment

in 1992, and by gender

GPA

less than 2.0

GPA

2.0 to 2.49

GPA

2.5 to 2.99

GPA

3.0 and above

Males

 Total $24,031 $25,696 $27,765 $28,613

Education attainment

 Some college (0–15 credits) 21,350 25,932 — 29,725

 Some college (16–40 credits) 24,711 24,357 22,525 23,164

 Some college (above 40 credits) 27,371 23,174 23,657 20,184

 Associate’s degree 24,163 23,646 25,433 25,823

 Bachelor’s degree 22,099 28,622 30,019 31,243

 Advanced degree — 24,193 29,844 30,568

Females

 Total 18,384 19,279 22,773 22,605

Education attainment

 Some college (0–15 credits) 20,372 18,562 14,907 19,015

 Some college (16–40 credits) 18,109 16,907 20,640 18,752

 Some college (above 40 credits) 17,779 18,337 20,953 16,994

 Associate’s degree 16,243 18,929 22,940 19,946

 Bachelor’s degree — 21,159 24,846 24,846

 Advanced degree — 22,283 21,331 26,210

—Sample size too small for reliable estimate.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
27

Early Work Experiences

Early work experiences are potentially associated with later life career development and

earnings in a number of ways. Such experiences may contribute to the acquisition of foundational

skills and may also reflect differences in student motivation in general or interest in employment

in particular. Early work experiences may also play an important role in the formation of careerrelated goals and aspirations. For most students, early work experiences accrue concurrently with

education and often serve to enrich aspects of the academic experience. For students who do not

attend college, the environment of work in many cases constitutes the primary mechanism

through which new skills and knowledge are acquired. In other words, for students who do not

attend college, work may be pursued not only for economic reasons, but also for learning new

skills (i.e., as an alternative to postsecondary education).

Employment While in High School: The High School Job Index

To help explore the relationship between high school employment, attainment, and earnings, a high school job index was constructed. The index was based on the incidence of employment and average weekly hours worked during the sophomore and senior school year and during

the summers after the sophomore and senior year. Students were then grouped into thirds based

on the overall distribution of index scores.22

As measured by the high school job index, work experiences did not vary by level of attainment, with the exception of students with no college, who were more likely to fall in the

bottom third of the High School Job Index than students at all higher levels of attainment (table

17). In part, this observation may reflect differences in student access to work opportunities as

well as differences in student motivation.23

 

22See appendix C for a more detailed discussion of the high school job index “Schjobgp.”

23While the association between academic preparation and high school work experiences suggests that student motivation is

likely to be a contributing factor behind student employment, differences in work experience by social and demographic background also suggest that access to employment opportunities is likely to be a contributing factor as well. Consider, for example,

that national youth unemployment rates through out most of the 1980s were nearly three times higher for black students as for

white students.
Early Work Experiences

28

Table 17Percentage distribution of 1980 sophomores who graduated from high school in 1982, by high

school job index and by level of education attainment in 1992

High school job index

Low

job experience

Middle

job experience

High

job experience

High school diploma only 43.9 21.0 35.1

Enrolled in any postsecondary education total 28.2 30.2 41.6

 Some college (0–15 credits) 32.6 22.3 45.1

 Some college (16–40 credits) 28.5 28.3 43.2

 Some college (above 40 credits) 29.5 28.8 41.7

 Students with some college total 30.1 26.5 43.4

 Associate’s degree 30.7 28.0 41.3

 Bachelor’s degree 25.7 33.4 40.9

 Advanced degree 24.3 36.6 39.1

NOTE: Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal Study of

1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

Comparative Earnings by High School Job Experience

For males with no college, students in the top third of the high school job index had higher

earnings than students in the bottom third (table 18). In certain instances, after considering high

school job experiences, students at different levels of attainment had the same earnings. For example, among students in the top third of the high school job index, males with an associate’s

degree had earnings similar to those of males at all lower levels of attainment. Likewise, among

students in the bottom third of the index, females with a bachelor’s degree had earnings similar

to those of females with some college who completed more than 40 credits.

Early Work Experience: The Early Work Index

To help explore the relationship between early work involvement and attainment and earnings, an early work index was constructed to reflect the intensity and continuity of work experiences from 1983 to 1986.24 The index was based on the cumulative months of employment over

the four-year period, average annual job tenure (defined as total number of months divided by the

number of employers per year) and average annual earnings.25

 

24In considering the early work index, it is important to recognize that this variable does not distinguish between work experience acquired while still in school from work experience acquired after leaving school. While this distinction may have bearing

on students’ earnings later in life, a later work index (e.g. 1987–1990) will in many instances be based on information concerning

the same position students had in 1991—the year used in this analysis to compare earnings.

25Following construction of the index, males and females were grouped into thirds based on the overall distribution of scores for

their respective gender. A more detailed discussion of the early work index is given in appendix C (“LFIA”).
Early Work Experiences

29

Table 18Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, by high

school job index, by level of education attainment in 1992 and by gender

High school job index

Low job

experience Middle job experience

High job

experience

Males

High school diploma only $19,852 $19,538 $24,396

Enrolled in any postsecondary education total 24,175 26,470 27,478

 Some college (0–15 credits) 21,513 27,758 25,329

 Some college (16–40 credits) 20,658 22,386 26,159

 Some college (above 40 credits) 22,241 21,235 26,137

 Associate’s degree or certificate 24,636 23,113 25,995

 Bachelor’s degree 29,023 30,304 29,708

 Advanced degree 28,723 30,600 30,041

Females

High school diploma total 13,525 13,819 15,665

Enrolled in any postsecondary education total 18,601 21,385 22,231

 Some college (0–15 credits) 18,978 17,303 20,236

 Some college (16–40 credits) 17,955 17,968 19,161

 Some college (above 40 credits) 19,938 17,064 18,567

 Associate’s degree or certificate 17,253 20,528 21,791

 Bachelor’s degree 22,433 23,853 25,880

 Advanced degree 22,401 24,934 24,770

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

In general, work involvement (as measured by the index) decreased with attainment, in

large part reflecting the time tradeoff that students face to pursue both academic and work activities. In the four years after high school (1983 to 1986), students who did not attend college and

students who completed 40 or fewer credits were more likely to fall in the top third of the early

work index than students with a bachelor’s or graduate degree (table 19). Conversely, students

with a bachelor’s or graduate degree were the most likely to fall in the bottom third of the index.

Comparative Earnings by Early Work Experience

Among students with comparable attainment, there were several instances in which students in the top third of the early work index had higher earnings than their counterparts in the

bottom third (table 20). These included males with a graduate degree, males with some college

who completed 15 or fewer credits, males with no college and females with no college.
Early Work Experiences

30

Table 19Percentage distribution of 1980 sophomores who graduated from high school in 1982, by early

work experience (1983–86), and by level of education attainment in 1992

Early work index

Low work

experience

Middle work

experience

High work

experience

High school diploma only 22.6 35.3 42.1

Enrolled in any postsecondary education total 41.1 32.9 26.0

 Some college (0–15 credits) 20.8 37.7 41.5

 Some college (16–40 credits) 22.5 35.9 41.6

 Some college (above 40 credits) 33.2 38.3 28.6

 Students with some college total 25.2 37.2 37.6

 Associate’s degree or certificate 38.5 35.2 26.3

 Bachelor’s degree 54.9 27.6 17.5

 Advanced degree 55.1 29.8 15.1

NOTE: Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

Table 20Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, by early

work experience (1983–86), by level of education attainment in 1992, and by gender

Early work index

Low work

 experience

Middle work

 experience

High work

 experience

Males

High school diploma only $15,509 $20,612 $25,332

Enrolled in any postsecondary education 24,843 26,597 28,950

 Some college (0–15 credits) 15,854 22,585 30,980

 Some college (16–40 credits) 23,043 23,222 24,822

 Some college (above 40 credits) 21,292 22,848 30,701

 Associate’s degree or certificate 23,382 24,953 27,042

 Bachelor’s degree 28,647 31,064 30,893

 Advanced degree 28,131 28,578 36,249

Females

High school diploma total 12,968 13,582 15,916

Enrolled in any postsecondary education 21,450 20,447 20,508

 Some college (0–15 credits) 16,870 20,342 18,374

 Some college (16–40 credits) 15,372 19,735 19,080

 Some college (above 40 credits) 19,499 18,678 17,030

 Associate’s degree or certificate 18,732 20,794 21,886

 Bachelor’s degree 24,290 23,660 24,942

 Advanced degree 24,373 23,940 24,926

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Early Work Experiences

31

At the same time, in certain instances, after considering early work experiences, students at

different levels of attainment had the same earnings. For example, among students in the top

third of the early work index, males or females with an associate’s degree had similar earnings

compared with males or females with bachelor’s degrees; and males who did not attend or complete college had similar earnings as males with an associate’s degree. In addition, males with no

college in the top third of the index had higher earnings than males in the bottom third who completed 15 or fewer credits.
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33

Controlling for Related Variables

Each of the variables discussed in this report illustrates how factors other than education

attainment are potentially associated with student earnings. Thus far, each variable has been considered separately. However, several of the variables may be related to one another and to other

background characteristics as well. For example, parent education attainment may not only play a

role in a student’s high school academic preparation but may be associated with college aspirations or early work experiences as well. To determine the influence of each variable on student

earnings while controlling for the interrelationship among variables, this analysis makes use of

linear regression analysis (see appendix C for details about the methods used) to produce adjusted means.

The regression analysis included students at all levels of attainment and uses annual earnings in 1991 as the dependent variable.26 Each of the model’s independent variables were entered

as dummy variables derived from the student characteristics discussed in this analysis including:

Gender

Ethnic/racial group

Family income in 1980

Parent education attainment

High school academic preparation

Educational aspirations

Type of initial institution attended

Academic focus

Depth versus breadth of curriculum

Undergraduate GPA

Employment experience while in high school

Early work experience 1983–1986

 

26As with all of the descriptive tables on mean earnings, the regression models excluded students with zero earnings. In addition,

a single record reporting annual earnings of $1.5 million was also excluded.
Controlling for Related Variables

34

In addition to the parameters listed above, dummy variables were included for high school

extra-curricular involvement and timing of entry into college,27 along with two control variables

to help account for variance in earnings that might otherwise be attributed to education attainment. These control variables included a dummy variable indicating that a student was not enrolled in college while employed during 1991; and a dummy variable indicating that a student

either had earnings below the 1991 minimum wage level, or worked less than full-time and/or

less than full year at minimum wage.28

The results of the regression analysis are shown in table 21. The first column of the table

shows the unadjusted average earnings for each variable—which represents the average earnings

of all students with that characteristic before controlling for other variables in the model. The

second column displays the corresponding adjusted average, for which the variation of all other

variables has been controlled. The italicized row is the comparison group for significance testing

and asterisks indicate instances where the average earnings for a specific row is significantly different from the comparison group within the row category.

To illustrate, the average earnings for students from families where neither parent had attended college was $20,426, compared with $24,978 for students from families where one or

both parents completed at least a bachelor’s degree. In part, the lower earnings of this group may

be directly associated with differences in parental education attainment (through, for example,

their capacity to help students secure employment), but lower earnings may also reflect differences in high school academic preparation, college participation or early work experiences as

well, which may also be associated with parent education attainment. After controlling for the

covariance among all the variables, the adjusted mean earnings for students from families where

neither parent attended college increased (to $21,868), while the adjusted earnings of students

whose parents had a bachelor’s degree or higher decreased (to $21,760). As a result, when the

adjusted means for both groups of students were compared, there was no longer an association

between parent attainment and earnings. In other words, the differences in unadjusted means

were the result of other associated factors.

 

27High school extra-curricular involvement was included an independent variable because of the potential role of such activities

in the acquisition of skills, knowledge and experiences that may contribute directly or indirectly to attainment and

earnings. Timing of entry into college was similarly considered—particularly with respect to attainment. Delayed entry, for example, may indicate a lack of interest in college, insufficient academic preparation, inadequate financial resources or other competing responsibilities such as parenthood, employment or military service. Definitions for each of the variables are given in

appendix B and summary statistics can be found in appendix tables A1–A4.

28In the absence of information about average weekly hours of employment or number of weeks worked annually, these two

variables represent potentially important surrogates of labor force involvement. Summary statistics showing the incidence of

students not enrolled in college and the average earnings of those enrolled and not enrolled in college are presented in appendix

tables A5 and A6. Summary statistics showing the incidence of students with earnings below the 1991 minimum wage level, or

who worked less than full-time and/or less than full year at minimum wage are given in appendix table A7.
Controlling for Related Variables

35

Table 21—Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, and the

adjusted mean earnings after taking into account the covariation of the variables listed in the

regression model

Unadjusted

average1

Adjusted

average2

Least squares

coefficient3

Standard

error4

 Total $22,033 $22,033 $17,057 $1,636

Gender

 Female 19,018* 19,836* -4,104 511

 Male 24,650 23,940 † †

Race/ethnicity

 White 22,581 21,937 † †

 Black 19,278* 21,798 -139 813

 Hispanic 20,422* 22,880 943 938

 Asian or Pacific Islander 26,719* 24,742 2,804 2,333

 Native American 20,038 22,798 861 2,365

Family income in 1980

 $0–14,999 18,926 20,803 † †

 $15,000–$25,999 21,587* 21,047 244 712

 $25,000–$39,999 23,784* 22,444* 1,641 716

 $40,000 or more 26,366* 24,173* 3,370 835

Parent educational attainment

 High school or less 20,426 21,882 † †

 Two-year degree or some college 22,457* 22,522 640 603

 Four-year degrees or higher 24,978* 21,760 -122 703

High school academic preparation5

 Lowest 18,653 21,133 † †

 Middle 21,512* 21,677 544 684

 Highest 27,856* 23,901* 2,768 984

Postsecondary aspirations in 1982

 No postsecondary aspirations 18,997 20,970 † †

 Vocational degree 19,908 20,869 -101 786

 Associate’s degree 21,949* 22,759* 1,789 858

 Bachelor’s degree 24,719* 22,537 1,566 926

 Advanced degree 26,592* 23,710* 2,739 1,019

Sector of postsecondary institution

 Public two-year or less $21,960 $21,407 † †

 Public four-year 21,614 21,998 $592 $703

 Private, not-for-profit less than four-year 25,431 22,298 891 1,740

 Private, not-for-profit four-year 26,871* 23,389* 1,982 886

 Private for-profit two-year or less 21,816 22,843 1,436 1,249

 Private for-profit four-year — 25,127 3,721 4,002
Controlling for Related Variables

36

Table 21—Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, and the adjusted mean earnings after taking into account the covariation of the variables listed in the regression model—Continued

Unadjusted

average1

Adjusted

average2

Least squares

coefficient3

Standard

error4

Undergraduate GPA

 Less than 2.00 20,994 20,945 † †

 2.00–2.49 22,999* 21,487 541 852

 2.49–2.99 24,822* 22,212 1,266 842

 3.00 or higher 25,172* 22,700* 1,754 843

Academic focus

 Vocational education focus 24,769 23,329 † †

 General education focus 23,411* 21,317* -2,012 610

 Incidental focus 20,290* 20,195 -3,134 2,346

Breadth of subjects index

 Equivalent of 12 subjects 23,029 21,296 † †

 Equivalent of eight subjects 25,481* 22,871* 1,575 705

 Equivalent of six subjects 25,230* 22,216 920 717

 Equivalent of four subjects 24,446 21,784 488 766

Educational attainment

 High school or less 18,848 20,125 † †

 Some college (0–15 credits) 20,654* 22,086 1,961 1,225

 Some college (15–40 credits) 20,816* 21,348 1,224 1,181

 Some college (above 40 credits) 21,381* 21,998 1,873 1,182

 Associate’s degree or certificate 21,473* 21,958* 1,833 848

 Bachelor’s degree 27,029* 24,751* 4,626 965

 Above a bachelor’s degree 27,087* 24,094* 3,969 1,259

High school work index

 Lowest involvement 19,315 21,382 † †

 Middle involvement 21,711* 21,498 115 692

 Highest involvement 24,161* 22,831* 1,448 640

Early work index

 Low 21,282 20,225 † †

 Medium 21,204 21,917* 1,692 597

 High 23,932* 24,425* 4,200 649

Enrolled in school in fall of 1991

 Not enrolled $22,245 $22,115 † †

 Enrolled 19,825* 19,703 $-2,412 $1,357

Full-time full-year at minimum wage

 Less than full-time full-year 3,848* 6,445* -17,353 824

 Full-time full-year 24,093 23,798 † †

High school extracurricular involvement

 Lowest 19,067 21,719 -422 756

 Middle 21,915* 22,104 -37 598

 Highest 23,542* 22,141 † †
Controlling for Related Variables

37

Table 21—Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, and the adjusted mean earnings after taking into account the covariation of the variables listed in the regression model—Continued

Unadjusted

average1

Adjusted

average2

Least squares

coefficient3

Standard

error4

Delay of college entry

 Enter college within 12 months 24,444 22,160 † †

 Enter college after 12 months 20,834* 21,617 -543 641

—Sample size too small for reliable estimate.

*p < .05.

†Not applicable for the reference group

1

HSB: 80/94 Data Analysis System. The italicized group in each category is the reference group for comparisons 2

Adjusted for differences associated with other variables in the table (see appendix C).

3

Least squares regression coefficient (see appendix C).

4

Standard error of LS coefficient, adjusted for design effect (see appendix C).

5

Academic resources index.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.

After taking into account all of the factors considered in this analysis, students’ education

attainment remains as a significant variable with differences in earnings observed across several

levels of attainment (see page two of table). Students with a bachelor’s or graduate degree, for

example, had higher earnings than students with no college, as did students with an associate’s

degree. For students with some college, however, there was no difference in earnings compared

with students with no college.

Additionally, after controlling for other factors, there were no differences in student earnings associated with race/ethnicity, high school extracurricular involvement, or timing of entry

into college. On the other hand, the remaining variables in the model were all associated with

higher earnings. Figure 2 summarizes the principal findings from the multivariate analysis.

In a second regression model (table 22), a series of dummy variables were included to represent the 10 largest undergraduate academic majors.29 While the inclusion of these variables

slightly improved the total explained variance in earnings, conclusions drawn from the results of

the first regression remain generally unchanged with the exception of academic focus, which is

no longer significant. Additionally, four of the 10 categories of academic major were significant

and all were associated with higher earnings than the “other” group. These majors included business, computer science, engineering, and health technologies.

 

29A student’s academic major not only reflects curricular aspects of a college education, such as areas of learning emphasis and academic rigor, but is potentially associated with a student’s aptitude and interest in certain fields of study and employment as well. For

example, just under half (47.5 percent) of all students from the sophomore class of 1980 who became physicians majored in the biological sciences as an undergraduate. Summary statistics for field of study are presented in appendix tables A8–A9.
Controlling for Related Variables

38

Figure 2—Summary of findings from regression analysis based on adjusted mean earnings

Demographic and

family background

High school

experience and

preparation

Postsecondary

experience

Early work

experience

Race— no difference in

earnings by race

Gender—females had

lower earnings than

males after controlling

for all other factors in

the model

Family income in

1980—students from

families with 1980 incomes of $25,000 and

above had higher earnings than students from

families with incomes

under $15,000.

Parent education attainment— no difference in earnings for

students from families

where one or both parents had a bachelor’s

degree or higher compared with students

whose parents had an

associate’s degree,

some college or no

college.

Academic preparation— students in the

top quintile of the academic resource index

had higher earnings

than students in the

bottom quintile.

Extra-curricular involvement—no difference in earnings by

student’s level of extracurricular involvement

College aspirations—students

who aspired to an associate’s

or advanced degree had higher

earnings than students with no

postsecondary aspirations.

Timing of entry —no difference in earnings for students

who entered college directly

after high school compared

with students who waited

twelve or more months

Initial type of institution attended—students who attended a 4-year private, notfor-profit college or university

higher earnings than students

who attended a public 2-year.

Degree (and credits) completed—students with an associate’s, bachelor’s or graduate

degree had higher earnings

than students with a high

school diploma or less.

College GPA—students with

at least a 3.0 had higher earnings than students with less

than a 2.0.

Academic focus—students

with a vocational focus had

higher earnings than students

with a general education focus.

Program Concentration—

students with breadth of

curriculum equivalent to seven

or eight subjects had higher

earnings than students with

breadth equivalent to nine or

more subjects.

Employment while in high

school—higher earnings

for students in the top

third of the high school

job index compared to

lowest.

Early work experience

(1983–86)—higher earnings for students in the

middle or top third of the

early work index compared to lowest third.
Controlling for Related Variables

39

Table 22—Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, and the

adjusted mean earnings after taking into account the covariation of the variables listed in the

regression model

Unadjusted

average1

Adjusted

average2

Least squares

coefficient3

Standard

error4

 Total $24,086 $22,033 $15,434 $1,704

High school academic preparation5

 Lowest 20,237 21,304 † †

 Middle 22,774* 21,775 471 682

 Highest 27,727* 23,460* 2,156 992

Academic focus

 Vocational 24,651 22,811 † †

 General 23,864* 21,616 -1,194 655

 Incidental 19,121* 20,228 -2,583 2,349

High school extracurricular involvement

 Lowest 22,779 21,599 -606 756

 Middle 23,842* 22,095 -110 596

 Highest 24,571* 22,205 † †

Postsecondary aspirations in 1982

 No postsecondary aspirations 20,291 21,010 † †

 Vocational degree 21,264 20,988 -21 787

 Associate’s degree 22,722* 22,728* 1,718 859

 Bachelor’s degree 25,086* 22,536 1,526 927

 Advanced degree 26,598* 23,545* 2,535 1,020

Enrolled in any postsecondary education

 High school or less 21,134 19,982 † †

 Some college (0–15 credits) 21,675* 22,204 2,222 1,226

 Some college (15–40 credits) 21,281* 21,319 1,337 1,179

 Some college (above 40 credits) 21,544* 21,774 1,792 1,182

 Associate’s degree or certificate 22,267* 21,980* 1,998 872

 Bachelor’s degree 26,905* 24,850* 4,868 968

 Above a bachelor’s degree 27,012* 24,512* 4,530 1,267

Family income in 1980

 $0–14,999 20,939 20,907 † †

 $15,000–25,999 23,037* 21,004 97 711

 $25,000–39,999 24,559* 22,416* 1,509 714

 $40,000 or more 27,598* 24,165* 3,259 833

College GPA

 Less than 2.00 21,375 20,894 † †

 2.00–2.49 22,752* 21,476 582 850

 2.49–2.99 25,196* 22,219 1,325 841

 3.00 or higher 25,180* 22,724* 1,829 843
Controlling for Related Variables

40

Table 22—Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, and the adjusted mean earnings after taking into account the covariation of the variables listed in the regression model—Continued

Unadjusted

average1

Adjusted

average2

Least squares

coefficient3

Standard

error4

Early labor force index

 Low $23,610 $20,310 † †

 Medium 23,482 21,843* $1,533 $597

 High 25,930* 24,405* 4,095 648

Delay of college entry

 Enter college within 12 months 24,784 22,174 † †

 Enter college after 12 months 22,060* 21,573 -601 641

Parent educational attainment

 High school or less 22,636 21,868 † †

 Two-year degree or some college 23,449* 22,509 640 601

 Four-year degree or higher 25,968* 21,800 -68 701

Enrolled in school in fall of 1991

 Not enrolled 24,651 22,120 † †

 Enrolled 19,726* 19,566 -2,554 1,354

Race/ethnicity

 White 24,379 21,977 † †

 Black 21,254* 21,549 -428 813

 Hispanic 23,498* 22,871 893 935

 Asian or Pacific Islander 28,037* 24,686 2,708 2,326

 Native American 22,829 22,779 801 2,357

High school work index

 Did not work in high school 22,244 21,422 † †

 Worked—sophomore/senior years 23,813* 21,533 112 690

 Worked extensively—sophomore/senior years 25,407* 22,781* 1,359 638

Gender

 Female 21,385* 19,885* -4,013 561

 Male 26,966 23,898 † †

Sector of postsecondary institution

 Public two-year or less 22,104 21,324 † †

 Public four-year 22,090 22,035 711 716

 Private, not-for-profit less than four-year 25,661 21,965 640 1,736

 Private, not-for-profit four-year 26,662* 23,501* 2,176 898

 Private for-profit two-year or less 21,306 23,068 1,744 1,252

 Private for-profit four-year — 24,728 3,403 3,993
Controlling for Related Variables

41

Table 22—Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, and the adjusted mean earnings after taking into account the covariation of the variables listed in the regression model—Continued

Unadjusted

average1

Adjusted

average2

Least squares

coefficient3

Standard

error4

Breadth of subjects index

 Equivalent of 12 subjects $22,949 $21,365 † †

 Equivalent of eight subjects 25,782* 22,914* $1,548 $707

 Equivalent of six subjects 25,432* 22,194 829 723

 Equivalent of four subjects 24,243 21,700 335 775

Full-time full-year at minimum wage

 Less than full time, full year 4,137* 6,588* -17,194 823

 Full time, full year 25,918 23,782 † †

Undergraduate major

 All other majors 23,537 20,653 † †

 Clerical and office administration 18,749* 22,492 1,839 1,234

 Business 25,350* 22,909* 2,256 762

 Computer science 25,733* 23,247* 2,594 1,028

 Education 18,659* 19,133 -1,520 1,201

 Engineering 28,010* 23,604* 2,952 1,006

 Dentistry, medicine, nursing 22,394 23,126 2,473 1,335

 Health technicians 22,434 23,858* 3,205 1,207

 Liberal, general studies 20,143* 21,049 396 1,180

 Precision production 24,118* 22,299 1,647 1,198

 Social science 15,796* 22,343 1,690 1,055

—Sample size too small for reliable estimate.

*p < .05.

†Not applicable for the reference group

1

The italicized group in each category is the reference group for comparisons. 2

Adjusted for differences associated with other variables in the table (see appendix C).

3

Least squares regression coefficient (see appendix C).

4

Standard error of LS coefficient, adjusted for design effect (see appendix C).

5

Academic resources index.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
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43

Summary and Conclusions

After adjusting for confounding factors associated with education attainment, the two regression models and resultant adjusted mean earnings support a number of conclusions. To begin, students with a graduate, bachelor’s, or associate’s degree had higher earnings than those

with no college. In contrast with other studies, however, there was no difference in earnings for

students with some college credits apart from degree completion after controlling for other aspects of student background.

Based on the ratio of the adjusted means, students with a bachelor’s degree earned about 23

percent more than those with no college. For students with an associate’s degree, the ratio of adjusted means represented about a nine percent differential compared to those with no college.

While students with some college, on average, had the same earnings as students with a

high school diploma, it is possible to define configurations of experience in which students with

some college achieved higher earnings than those with no college. For example, students whose

college coursework could be characterized as vocational or students with cumulative GPAs of

3.0 or higher had adjusted mean earnings that were $1,754 and $2,012 above their counterparts

after controlling for attainment and other related variables.

More generally, the association between students’ earnings and such “within-college effects” as type of institution, grades, undergraduate major, academic focus, and breadth versus

depth of subjects studied illustrate that college curriculum and specific aspects of the college experience figure prominently in the economic returns to a college education. In addition, the lack

of a return for students with some college who completed 40 or more credits (but no degree) suggests that credit production in the absence of a meaningful integration of courses contributes little

to individual earnings and/or that there are considerable economic gains that can be attributed to

the degree credential itself.30

Apart from attainment and selected aspects of the college experience, the findings from this

analysis suggest that labor force experience constitutes an important component of the earnings

 

30To assess whether students who had completed substantially more than 40 credits had the same earnings as those at lower levels of attainment, a third regression was conducted using a revised credit variable that incrementally expanded credit bands with a

top band of 120 or more credits. As with the prior models, the results of this regression failed to show a significant difference in

earnings for students with less than an associate’s degree, regardless of credit production.
Summary and Conclusions

44

equation. Based on the adjusted mean earnings, workforce experience during high school and

during the four years immediately following high school can contribute significantly to individual earnings. While this association potentially reflects differences in motivation as well as experience, the findings nonetheless suggest that an enriching early work experience may provide

students with an important channel for such motivation, and in effect mitigate some of the economic disadvantages of not having a college degree.

As with questions concerning college access, however, higher rates of unemployment and a

greater likelihood of falling into the bottom third of the high school job index or the early work

index suggest that some students, such as black and American Indian students (who are less

likely to complete college), may have less access to enriching employment opportunities as well.

In broader terms, the association between education attainment, early employment and

earnings suggest that the greatest gains in individual earnings are most likely to accrue through a

combination of work and postsecondary education. And, while the responsibilities of employment may compete with educational activities, work experiences in some instances can be mutually facilitating and mutually reinforcing.

The last set of observations concerns the influences of socioeconomic background and economic mobility. In combination, several elements of students’ background, including family income and high school academic preparation were associated with earnings both directly and

indirectly through an association with higher attainment.

 While the findings from this analysis reaffirm the central role of education (at both the

high school and postsecondary level) as a vehicle of social mobility, in actuality, for the sophomore class of 1980, the earnings distribution of students 10 years after high school remains

closely associated with socioeconomic status during high school. In other words, while education

is positively related to individual earnings—irrespective of socioeconomic background—the direct and indirect effects of family income still constitute a dominant factor in the formation of an

individual’s earning capacity.

Nowhere is this impact more clearly illustrated than with the racial/ethnic background of

students. After controlling for all other characteristics in the framework, there was no difference

in student earnings by race/ethnicity. While at one level this finding suggests that something of

an economic parity with respect to race/ethnicity exists in the labor market, it is crucial to recog-
Summary and Conclusions

45

nize the extent to which this balance is offset by the overall disparity in attainment for blacks,

Hispanics, and American Indians compared with whites or Asians.31

While observed differences in earnings by race/ethnicity are more directly attributable to

differences in attainment than other factors, the same cannot be said with respect to gender. Indeed, for the sophomore class of 1980, females were more likely to attend college than males and

had equivalent baccalaureate and advanced degree rates of attainment. At the same time, after

controlling for all factors in the model, there remains a pronounced earnings differential by gender with an adjusted mean earnings for females that is approximately 18 percent less than for

males.

While this disparity may in part be accounted for by differences in occupational employment—which was not considered in the earnings framework—this finding nonetheless brings

with it a number of implications including questions about comparative differences in a college

education’s economic return on investment, and in the level of college debt that students may

ultimately be able to assume. At the same time, the positive association between attainment and

earnings remains, regardless of gender. Therefore, while economic parity, by definition, cannot

be achieved through offsets in attainment for those who are otherwise disadvantaged, attainment

nonetheless serves to mitigate those disparities.

 

31For the sophomore class of 1980, blacks, Hispanics, and American Indians were less than half as likely as white students and

less than one-third as likely as Asians to attain a bachelor’s degree.
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47

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49

Appendix A—Regression Analysis Control Variables

Table A1Percentage distribution of 1980 sophomores who graduated from high school in 1982, by high

school extracurricular experience, and by level of education attainment in 1992

Low

extracurricular

involvement

Middle

extracurricular

involvement

High

extracurricular

involvement

High school diploma only 42.1 30.1 27.8

Enrolled in any postsecondary education total 16.1 27.0 56.9

 Some college (0–15 credits) 27.3 32.0 40.7

 Some college (16–40 credits) 18.9 31.9 49.2

 Some college (above 40 credits) 13.0 32.0 54.9

 Associate’s degree 22.4 29.3 48.4

 Bachelor’s degree 10.5 22.3 67.1

 Master’s degree 7.9 20.9 71.2

NOTE: Based on student’s ranking in the bottom, middle and top third of the extracurricular index. Row percentages may not

add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Appendix A—Regression Analysis Control Variables

50

Table A2Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, by high

school extracurricular experience, by level of education attainment in 1992, and by gender

Low extracurricular

involvement

Middle extracurricular

involvement

High extracurricular

involvement

Males

High school diploma only $20,426 $22,518 $23,084

Enrolled in any postsecondary education total 24,671 26,893 27,736

 Some college (0–15 credits) 24,742 26,825 23,193

 Some college (16–40 credits) 25,170 24,856 22,661

 Some college (above 40 credits) 21,590 24,441 24,926

 Associate’s degree or certificate 23,826 23,936 26,612

 Bachelor’s degree 26,304 28,937 30,678

 Advanced degree 26,093 33,236 29,299

Females

High school diploma only 13,459 14,314 15,041

Enrolled in any postsecondary education total 20,858 20,564 22,048

 Some college (0–15 credits) 17,615 19,672 19,243

 Some college (16–40 credits) 21,208 16,985 18,367

 Some college (above 40 credits) 25,593 17,064 17,705

 Associate’s degree or certificate 21,142 19,705 20,032

 Bachelor’s degree 20,828 24,859 24,414

 Advanced degree — 22,114 24,832

—Sample size too small for reliable estimate.

NOTE: Based on student’s ranking in the bottom, middle and top third of the extracurricular index.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Study,

Sophomore Cohort, Fourth Follow-up Survey 1992, Data Analysis System.
Appendix A—Regression Analysis Control Variables

51

Table A3Percentage distribution of 1980 sophomores who graduated from high school in 1982 and enrolled

in postsecondary education, by timing of entry into college, and by level of education attainment in

1992

Direct entry

(12 or fewer months)

Delayed entry

(more than 12 months)

 Total 80.6 19.4

Education attainment

 Some college (0–15 credits) 50.2 49.8

 Some college (16–40 credits) 72.9 27.1

 Some college (above 40 credits) 82.6 17.5

 Associate’s degree or certificate 72.2 27.8

 Bachelor’s degree 93.1 6.9

 Advanced degree 94.7 5.4

NOTE: Row percentages may not add to 100 due to rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Appendix A—Regression Analysis Control Variables

52

Table A4Average 1991 earnings of 1980 sophomores who graduated from high school in 1982 and enrolled

in postsecondary education, by timing of entry into college, by level of education attainment in

1992, and by gender

Direct entry

(12 or fewer months)

Delayed entry

(more than 12 months)

Males

 Total $27,996 $24,135

Education attainment

 Some college (0–15 credits) 23,056 26,444

 Some college (16–40 credits) 23,893 26,056

 Some college (above 40 credits) 26,206 19,096

 Associate’s degree or certificate 25,625 22,913

 Bachelor’s degree 30,408 24,496

 Advanced degree 30,180 —

Females

 Total 21,956 20,121

Education attainment

 Some college (0–15 credits) 19,363 19,088

 Some college (16–40 credits) 19,295 15,015

 Some college (above 40 credits) 17,902 24,452

 Associate’s degree or certificate 19,906 20,623

 Bachelor’s degree 24,415 20,922

 Advanced degree 24,313 —

—Sample size too small for reliable estimate.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Appendix A—Regression Analysis Control Variables

53

Table A5—Percentage of 1980 sophomores who graduated from high school in 1982 not enrolled in college in

1991, by level of education attainment in 1992

Not enrolled in college

High school diploma only 99.1

Enrolled in any postsecondary education

 Some college (0–15 credits) 96.0

 Some college (16–40 credits) 94.9

 Some college (above 40 credits) 93.4

 Associate’s degree or certificate 95.4

 Bachelor’s degree 97.4

 Advanced degree 87.1

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Appendix A—Regression Analysis Control Variables

54

Table A6—Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, by level of

education attainment in 1992, by enrollment in college in 1991, and by gender

Not enrolled in college Enrolled in college

Males

High school diploma or less total $21,928 —

Enrolled in any postsecondary education

 Some college (0–15 credits) 25,143 —

 Some college (16–40 credits) 24,237 —

 Some college (above 40 credits) 26,098 —

 Associate’s degree or certificate 25,793 —

 Bachelor’s degree 30,686 $20,619

 Advanced degree 32,415 26,501

Females

High school diploma or less total 14,338 —

Enrolled in any postsecondary education

 Some college (0–15 credits) 19,116 —

 Some college (16–40 credits) 18,358 —

 Some college (above 40 credits) 17,254 —

 Associate’s degree or certificate 19,547 18,467

 Bachelor’s degree 24,960 —

 Advanced degree 25,653 19,887

—Sample size too small for reliable estimate.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Appendix A—Regression Analysis Control Variables

55

Table A7—Percentage of 1980 sophomores who graduated from high school in 1982 who worked less than

full-time full-year in 1991, by level of education attainment in 1992

Less than full-time full-year

employed earning above

minimum wage

High school diploma or less total 7.0

Enrolled in any postsecondary education total

 Some college (0–15 credits) 6.0

 Some college (16–40 credits) 4.0

 Some college (above 40 credits) 3.9

 Associate’s degree or certificate 3.7

 Bachelor’s degree 2.2

 Advanced degree 2.5

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Appendix A—Regression Analysis Control Variables

56

Table A8Percentage distribution of 1980 sophomores who graduated from high school in 1982, by level of

education attainment in 1992, and by undergraduate major

Some

college

Associate’s

degree

Bachelor’s

degree or higher

 Total 100.0 100.0 100.0

Undergraduate major

 Business administration and management 23.6 8.9 20.6

 Engineering 8.4 7.8 7.8

 Social science 5.2 2.2 14.7

 Computer and information science 10.2 4.6 6.2

 Clerical and office administration 6.0 13.8 0.4

 Liberal or general studies 7.2 7.0 4.6

 Precision production 4.3 13.2 0.4

 Health related technicians 2.0 10.6 3.8

 Education 7.5 1.1 5.9

 Dentistry, medicine and nursing 6.0 4.1 2.7

 Communications 2.6 0.7 5.5

 Consumer services 0.7 7.5 0.1

 Marketing and distribution 1.1 3.8 2.8

 Film, fine and performing art 3.1 0.6 3.6

 Biological sciences 1.1 0.4 4.9

 Protective services 2.4 3.0 1.0

 Agriculture and resource management 2.3 1.9 1.3

 Home economics 0.3 2.6 0.6

 English or American literature 0.4 0.0 3.1

 Physical science 0.7 0.1 2.5

 Allied health: general and other 0.9 1.8 0.4

 Law 0.7 1.7 0.1

 Social work or social service 0.5 1.0 1.0

 Mathematics 0.6 0.2 1.4

 Philosophy 0.6 0.4 1.1

 Architecture or environmental design 0.5 0.4 0.6

 Graphic or industrial design 0.4 0.2 0.8

 Transportation 0.6 0.3 0.3

 Foreign language 0.0 0.0 1.1

 Textiles/fashion 0.0 0.2 0.4

 Communication technology 0.1 0.2 0.1

 Other public administration 0.1 0.0 0.1

 Military science and technology 0.0 0.0 0.1

 Library or archival science 0.0 0.0 0.0

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Appendix A—Regression Analysis Control Variables

57

Table A9Average 1991 earnings of 1980 sophomores who graduated from high school in 1982, by level of

education attainment in 1992, and by undergraduate major

Some college

Associate’s

degree

Bachelor’s

degree or higher

All

students

 Total $21,766 $22,343 $27,066 $24,376

Undergraduate major

 Clerical and office administration 16,690 20,611 — 18,927

 Architecture or environmental design ——— 20,719

 Film, fine and performing art 20,316 — 22,034 21,183

 Biological sciences — — 22,864 22,658

 Business administration and management 23,734 23,555 28,771 26,226

 Communications 21,038 — 24,071 23,654

 Communication technology ——— 22,445

 Computer and information science 20,306 22,009 33,251 25,865

 Consumer services — 14,515 — 14,948

 Graphic or industrial design ——— 22,758

 Textiles/fashion ——— 23,202

 Education 17,448 — 19,551 18,684

 English or American literature — — 24,998 24,693

 Engineering 23,279 25,812 34,837 29,090

 Allied health: general and other ——— 23,692

 Dentistry, medicine and nursing 18,794 23,530 31,177 23,938

 Health related technicians 23,805 23,123 27,335 24,604

 Home economics ——— 17,948

 Foreign language ——— 21,160

 Law ——— 20,177

 Liberal or general studies 20,183 21,404 21,470 20,965

 Library or archival science ————

 Mathematics — — 29,417 26,963

 Military science and technology ————

 Marketing and distribution — 23,067 29,598 25,728

 Agriculture and resource management 24,699 — 29,735 27,700

 Philosophy — — 21,321 18,654

 Physical science — — 28,052 27,538

 Precision production 22,649 24,501 — 23,832

 Protective services 27,695 25,957 21,162 25,239

 Social work or social service ——— 16,798

 Other public administration ——— 25,161

 Social science 26,053 — 27,929 27,206

 Transportation ——— 30,498

—Sample size too small for reliable estimate.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
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59

Appendix B—Variable Glossary

The variables used in this study are listed below. These items were either taken directly from the High School and

Beyond Study Data Analysis System (see appendix C for a description of the DAS) or derived by combining one or

more items in the survey. An asterisk indicates that the variable was derived.

Glossary Index

FAMILY–DEMOGRAPHIC

Gender ................................................................. SEX

Ethnic/racial background .................................. RACE

Family income ............................................. FAMINC

Parent education attainment..........................PARED2

HIGH SCHOOL EXPERIENCE

Academic resource index.......................... ACREDEX

Extracurricular index ............................ COCRINDX*

POSTSECONDARY EXPERIENCE

Education attainment ..................................EDATT4*

Total credits completed...................................TCRED

Type of institution first attended................TRUSECT

Educational aspirations ............................... EDASP82

Timing of college entry.............................MONSTRT

Academic focus........................................ACFOCUS*

Program concentration index ..................HERSIDX2*

Undergraduate major field of study ........... UGMAJ2*

Undergraduate GPA.............................................GPA

WORK EXPERIENCE

Early work index............................................... LFIA*

High school work index .........................SCHJOBGP*

OUTCOME VARIABLES

1991 earnings.............................................Y4301B9Z

POPULATION SAMPLE WEIGHTS

HS&B general population weight ...........PANEL5WT

Postsecondary education population

 weight .........................................................PSEWT3

*Variables created for this analysis derived from other

variables in the HS&B and PETS data file.
Appendix B—Variable Glossary

60

Academic focus ACFOCUS

Represents the preponderance of type of classes students completed as undergraduates. Academic focus was created

for this study as a curriculum content variable based on the following approach: Using the PETS file, individual

courses were coded as either vocational (indicating occupation specific training), general education (indicating liberal arts and general postsecondary preparation) or incidental (indicating leisure, entertainment or recreational

classes). The coding of courses was based, in large part, on the content descriptions as published in “The New College Course Map and Transcript Files: Changes in Course-Taking and Achievement, 1972–1993” by Clifford Adelmen, Office of Educational Research and Improvement, U.S. Department of Education, 1995. Selected examples of

vocational courses include agriculture and animal production, hotel management, radio/TV news broadcasting and

writing, computer programming, metallurgical engineering, drafting, dental hygiene, speech-language pathology,

hematology, fire protection, pipefitting and plumbing. Examples of general education include: East Asian studies,

American Literature, biology, calculus, anthropology, economics, geography, history, political science and dance.

Examples of incidental courses include aerobics, First Aid and Safety, Water Recreation, Yoga, Scuba/Skin Diving,

coping skills, varsity athletics, games, sex and birth related health practices. A student’s designation was based on

which of the three categories accounted for the largest share of total credits earned. The academic focus variable was

constructed to explore whether an emphasis on vocational versus liberal arts courses studied is associated with differences in student earnings after college.

Academic resource index ACREDEX

Based on a composite weighting of four criteria: intensity of the high school academic curriculum (e.g. the number of

academic units completed by subject area), the high school percentile class rank, and high school GPA, and students’

score on a standardized composite. The Acres variable grouped students by quintile. For this analysis, students were

aggregated into three categories: the top 20 percent, the middle 60 percent, and the bottom 20 percent.

Extracurricular index COCRINDX

Reflects student depth (e.g. participant versus leadership role) and breath (e.g. number of different activities) of involvement in extracurricular activities while in high school. The extracurricular index was created for this study

based on the total number of extracurricular activities (up to 16) and level of involvement (did not participate, active

participant, leader) as reported in the second follow-up. Extracurricular experiences may help students acquire skills,

knowledge, and experiences that can contribute to their effectiveness and position in the labor market later in life.

Extracurricular involvement also potentially indicates a greater level of engagement in high school and reinforcement

of classroom learning through outside experiences.

Education aspirations EDASP82

Potentially reflect student’s interest and motivation concerning postsecondary education, training, and credentialing,

as well as high school academic preparation and occupational/career aspirations.

Education attainment EDATT4

This variable represents a student’s highest educational experience or education attained. This variable was derived

using the transcript variable education attainment (HighDeg) for those with transcript information. For those without

reported transcript information, the self-reported education attainment variable (HighDeg) was used to determine the

highest level of education attained. Both variables were collapsed into seven categories: 1) high school or less; 2)

some college (0–15 credits); 3) some college (16–40 credits); 4) some college (more than 40 credits); 5) Associate’s

Degree or Certificate; 6) Bachelor’s degree; and 7) above a bachelor’s degree.
Appendix B—Variable Glossary

61

Family income FAMINC

Student’s family income in 1980 which has be grouped into four broad categories, under $15,000, $15,000 to

$24,999, $25,000 to $39,999 and $40,000 and above. In 1998 dollars (based on the CPI-U) the bands would roughly

be equivalent to under $30,000, $30,000–$49,999, $50,000 to $79,999 and $80,000 and above.

Undergraduate GPA GPA

Represents the cumulative undergraduate grade point average for credits completed. GPA scores were banded into

quartiles based on the distribution of grades for all undergraduate students. To allow for potential differences in academic performance across sectors, the distribution of GPA scores are shown separately by sector. College GPA potentially reflects student’s academic performance and mastery of subject matter as well as motivation, and potentially

contributes to an individual’s credentialing and labor market position.

Program concentration index HERSIDX2

Measures the depth versus breadth or dispersal of courses students completed across a possible 116 subjects. The

index was created for this study and is based on an algorithm known as the Hirschman–Herfindahl concentration

index32 (that has been used to measure racial segregation in urban communities as well as industrial concentration).

The index first calculates the percent share of courses completed in each academic program (Crscode) category.

Each percent value is squared and all values are summed. The summed score is then inverted, resulting in a concentration score with a potential numeric range from 1 (indicating that all courses were within a single subject) to 1/N,

with N representing the total number of program categories (indicating that all courses were evenly distributed across

the equivalent of N subjects). The concentration index was constructed to explore whether differences in depth versus breadth of subjects studied is associated with differences in student earnings after college.

Early work index LFIA

Reflects the depth and breadth of students’ labor force involvement in the first four years after high school (1983 to

1986). The early work index was created for this study. The index is a summary measure based on three criteria—

cumulative months of employment over the four years, average annual job tenure (defined as total number of months

divided by the number of employers), and average annual earnings. The index assigned up to 10 points for each criteria based on decile rankings. Total points were then summed resulting in a range from three to 30. For students

who were missing values for one of the three criteria, summed scores were divided by two-thirds. Students who were

missing values for two or three of the criteria were coded as missing. Students were then grouped into the top, middle, and bottom third based on their summary score. The index reflects the level of experience students have acquired in the work and potentially reflects gains in skill acquisition, work-related credentials, job tenure, and job

content, all of which may contribute to higher earnings later in life.

Timing of college entry MONSTRT

Delay in college enrollment potentially reflects competing responsibilities, lack of interest or motivation, insufficient

preparation or financial resources, or lack of planning. Students were classified into one of two groups based on time

of entry into college: 12 or fewer months after high school (with a majority of this group entering in the fall following their senior year); and more than 12 months after high school (with a majority of this group entering college

within two years after graduation from high school).

 

32For a brief overview see Bannock, Baxter, and Rees (1972).
Appendix B—Variable Glossary

62

HS&B general population weight PANEL5WT

General population weight used for the multivariate analysis and for tabulation of all students with no college. Covers all follow-ups of the sophomore class of 1980 (80–82–84–86–92).

Parent education attainment PARED2

Adjusted level of parents’ highest education, taking into account parents’ occupation. Conflicts between studentreported occupation and highest level of education for their parents were resolved only in those cases involving occupations that required at least some college, e.g., school teacher, lawyer. Conflicts were first resolved for father and

mother separately. This variable takes the highest level of education of either parents. For this analysis, parent education attainment was grouped into three categories; no college, some college/associate’s, and bachelor’s or higher.

Postsecondary education population weight PSEWT3

This population weight is the most restrictive of the three new weights offered for analyses of postsecondary attendance phenomena. It was established in the same manner with the same components as PSEWT2 except that the divisor consisted for the RAWWTS only for those HSBSTAT=1 students with complete or probably complete

undergraduate records (COMPLETE=1 or COMPLETE=2), then multiplied by the factors from the 29 stratification

cells. This is an expansion weight for the people who continued their education after high school at a true postsecondary level and whose undergraduate transcripts present a full course-taking record. Analysts are advised to use

this weight for all topics derived from course-taking, e.g. credits, grades, course participation, etc. Analysts who wish

to include those students for whom COMPLETE=3 but who had earned bachelor’s degrees must modify PSEWT3.

Ethnic/racial background RACE

Reflects a students ethnic/racial background including six possible categories. White, Black, Hispanic, Asian or Pacific Islander, Native American or Alaskan native and Missing. This information is a recode of variables from CATI,

earlier follow-ups, and other (Adelman) information that moved 26 cases from missing to known status based on the

PETS Student file

High school job index SCHJOBGP

The student job index was created for this study and represents the extent to which students were employed (the average weekly number of hours worked and approximate duration of employment) during the high school sophomore

(using variable FY24), summer after sophomore (using variable FY36) and senior year (using variable FY37). The

student job index potentially reflects early interest in career and labor force activities as well as the acquisition of

basic job skills and potentially reflects motivation and positive early experiences that can influence labor market

position later in life.

Gender SEX

Indicates a student’s sex. Gender variable was used for comparisons of student earnings and in the multivariate

analysis.
Appendix B—Variable Glossary

63

Total credits completed TCRED

Represents a count of the total number of postsecondary credits earned at the undergraduate. The source variable for

this information comes from the transcript file.

Type of institution first attended TRUSECT

Reflects the type (Carnegie classification and control) of postsecondary institution students first attended. Sector

attended is broadly associated with institutional selectivity and potentially may influence after college earnings directly or indirectly through the educational services and resources provided including instruction and student services, institutional prestige and organizational and alumni networks.

Undergraduate major field of study UGMAJ2

Categorical variable showing the undergraduate major both for degree and non-degree holders with a total of 34

categories. For students who completed a bachelor’s or associate’s degree the variable was derived from MAJCOD5.

For non-degree holders the variable was derived from Y4203N01- major at first institution with a recoding of the

response categories to conform with the categories as reported by MAJCOD5.
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65

Appendix C—Technical Notes and Methodology

The High School and Beyond Fourth Follow-up Study

High School and Beyond (HS&B) is a longitudinal study that followed two cohorts of students. It began with a nationally representative sample of over 58,000 students who were high

school sophomores and seniors in 1980. An extensive survey was administered in the base year

along with a battery of cognitive tests. Both cohorts were followed up at two-year intervals

through 1986, and the sophomore cohort was followed up a fourth time in 1992. Cognitive tests

were administered to the sophomore cohort during the first follow-up survey, when most were

high school seniors. In addition, high school transcripts were collected and coded. The fourth

follow-up included a collection of postsecondary transcripts for members of the sophomore cohort who had continued their education beyond high school. The HS&B Postsecondary Education Transcript Study (PETS) includes transcript information to September 1993.

Sample weights. All analyses in this report are weighted to compensate for unequal probability of selection into the HS&B sample and to adjust for nonresponse. Because this report relies extensively on PETS data and requires complete information on postsecondary course taking,

all analyses of students with at least some postsecondary education were weighted based on those

students for whom complete transcript information was available (weight variable PSEWT3). For

students with no college, the analysis used the general population weight from the fourth followup (Panel5). Because students with and without a college education required separate weights,

population totals or summary statistics representing all students have not been provided. All of

the regression models used in this analysis relied on the Panel5 weight. The selection of this

weight was necessary to have sufficient representation of students at all levels of attainment.33

Accuracy of Estimates

The statistics in this report are estimates derived from a sample. Two broad categories of

error occur in such estimates: sampling and nonsampling errors. Sampling errors occur because

observations are made only on samples of students, not on entire populations. Nonsampling er-

 

33An alternative series of regression models were run, which “spliced” the row and column values for the dummy variable no

college from the correlation matrix using the Panel5 weight into the correlation matrix using the PSEWT3. The resultant regression outputs, however, yielded substantially different (and often illogical) results, compared with the regression outputs based on

either weight alone.
Appendix C—Technical Notes and Methodology

66

rors occur not only in sample surveys but also in complete censuses of entire populations. Nonsampling errors can be attributed to a number of sources: inability to obtain complete information

about all students in all institutions in the sample (some students or institutions refused to participate, or students participated but answered only certain items); ambiguous definitions; differences in interpreting questions; inability or unwillingness to give correct information; mistakes in

recording or coding data; and other errors of collecting, processing, sampling, and imputing

missing data.

Data Analysis System

The estimates presented in this report were produced using the HS&B: 80/92 Data Analysis

System (DAS). The DAS software makes it possible for users to specify and generate their own

tables from the HS&B: 80/92 data. With the DAS, users can replicate or expand upon the tables

presented in this report. In addition to the table estimates, the DAS calculates proper standard

errors and weighted sample sizes for these estimates. For example, table C1 contains standard

errors that correspond to table 1 in the text, and was generated by the DAS. If the number of

valid cases is too small to produce a reliable estimate (fewer than 30 cases), the DAS prints the

message “low N” instead of the estimate.

All variables in the DAS are integers. To preserve decimal precision for certain variables,

values in the DAS have been multiplied by a factor of 10. For example, grade point averages

range from 0–400 in the DAS. When averages for such variables appear in this report, estimates

and standard errors were divided by the appropriate factor of 10 to restore the original scale.

In addition to tables, the DAS will also produce a correlation matrix of selected variables to

be used for linear regression models. Included in the output with the correlation matrix are the

design effects (DEFTs) for each variable in the matrix. Since statistical procedures generally

compute standard errors based on an assumption of simple random sampling, the standard errors

must be adjusted with the design effects to take into account HS&B’s complex sample design.

(See discussion under “Statistical Procedures” below for the adjustment procedure.)

For more information about the HS&B: 80/92 and other Data Analysis Systems, consult the

NCES DAS website (www.nces.ed.gov/das) or its West coast mirror site (www.pedar-das.org), or

contact:

Aurora D’Amico

NCES Data Development and Longitudinal Studies Group

1910 K St. NW

Washington, DC 20006

(202) 502-7334

Internet address: aurora_d’amico@ed.gov
Appendix C—Technical Notes and Methodology

67

Table C1—Standard errors for table 1: Average 1991 earnings of 1980 sophomores who graduated from high

school in 1982, by level of education attainment in 1992, by gender, by race/ethnicity, by family income in 1980, and by parent’s education attainment

High school

or less

Some

college

(0–15

credits)

Some

college

(15–40

credits)

Some

college

(above 40

credits)

Associate’s

degree or

certificate

Bachelor’s

degree

Advanced

degree

Males

 Total $406 $1,690 $1,015 $1,259 $721 $567 $1,043

Race/ethnicity

 White 477 2,030 1,243 1,533 763 625 1,128

 Black 1,064 — 1,963 2,669 2,610 2,002 3,235

 Hispanic 1,094 1,785 3,085 3,178 3,845 2,137 5,320

 Asian or Pacific Islander ————— 1,969 6,509

Family income in 1980

 $0–14,999 930 2,413 2,150 1,842 2,571 1,452 3,303

 $15,000–24,999 864 1,728 1,070 1,423 1,118 1,259 1,981

 $25,000–39,999 784 1,464 1,626 1,374 1,095 808 1,532

 $40,000 or more 1,658 8,201 4,775 4,288 2,321 1,308 1,627

Parent’s education attainment

 No college 523 1,256 997 1,611 1,284 1,031 2,485

 Some college/associate’s 765 1,197 1,246 2,759 948 1,133 1,718

 Bachelor’s degree or higher 1,287 7,426 3,977 1,888 1,573 907 1,370

Females

 Total 362 1,296 919 1,146 734 526 783

Race/ethnicity

 White 415 1,600 944 1,611 808 535 877

 Black 1,078 2,231 3,498 1,164 2,588 1,030 2,460

 Hispanic 979 1,906 1,776 1,886 1,766 1,344 3,833

 Asian or Pacific Islander ————— 1,855 2,057

Family income in 1980

 $0–14,999 828 1,578 1,507 1,486 986 2,908 2,244

 $15,000–24,999 562 1,348 1,331 1,525 1,923 906 1,393

 $25,000–39,999 1,045 1,600 1,664 1,106 1,307 861 1,194

 $40,000 or more 1,035 — 1,902 1,257 1,520 940 1,588

Parent’s education attainment

 No college 436 2,237 956 999 1,166 892 1,861

 Some college/associate’s 713 1,957 1,751 3,015 820 1,167 1,217

 Bachelor’s degree or higher 1,251 2,339 1,778 1,037 2,496 681 1,218

—Sample size too small for reliable estimate.

NOTE: Native Americans were not included due to low Ns.

SOURCE: U.S. Department of Education, National Center for Education Statistics, 1980 High School and Beyond Longitudinal

Study of 1980, Sophomores (HS&B: So 1980/92), Data Analysis System.
Appendix C—Technical Notes and Methodology

68

Statistical Procedures

Two types of statistical procedures were employed in this report: testing differences between means (or proportions), testing for linear trends, and adjustment of means after controlling

for covariation among several variables. Each procedure is described below.

Differences Between Means

The descriptive comparisons were tested in this report using Student’s t statistic. Differences between estimates are tested against the probability of a Type I error,34 or significance

level. The significance levels were determined by calculating the Student’s t values for the differences between each pair of means or proportions and comparing these with published tables of

significance levels for two-tailed hypothesis testing.

Student’s t values may be computed to test the difference between estimates with the following formula:

2

2

2

1

1 2

se se

E E

t

+

− = (1)

Where E1 and E2 are the estimates to be compared and se1 and se2 are their corresponding standard errors. This formula is valid only for independent estimates. When estimates are not independent, a covariance term must be added to the formula:

E -E

se + se - 2(r)se se

1 2

1

2

2

2

1 2

 (2)

Where r is the correlation between the two estimates.35 This formula is used when comparing

two percentages from a distribution that adds to 100. If the comparison is between the mean of a

subgroup and the mean of the total group, the following formula is used:

E E

se se p se

sub tot

sub tot sub

−

+ − 22 2 2 

(3)

 

34A Type I error occurs when one concludes that a difference observed in a sample reflects a true difference in the population

from which the sample was drawn, when no such difference is present.

35U.S. Department of Education, National Center for Education Statistics, A Note from the Chief Statistician, no. 2, 1993.
Appendix C—Technical Notes and Methodology

69

Where p is the proportion of the total group contained in the subgroup.36 The estimates, standard

errors, and correlations can all be obtained from the DAS.

There are hazards in reporting statistical tests for each comparison. First, comparisons

based on large t statistics may appear to merit special attention. This can be misleading, since the

magnitude of the t statistic is related not only to the observed differences in means or percentages

but also to the number of students in the specific categories used for comparison. Hence, a small

difference compared across a large number of students would produce a large t statistic.

A second hazard in reporting statistical tests for each comparison occurs when making

multiple comparisons among categories of an independent variable. For example, when making

paired comparisons among different levels of income, the probability of a Type I error for these

comparisons taken as a group is larger than the probability for a single comparison. When more

than one difference between groups of related characteristics or “families” are tested for statistical significance, one must apply a standard that assures a level of significance for all of those

comparisons taken together.

Comparisons were made in this report only when p<.05/k for a particular pairwise comparison, where that comparison was one of k tests within a family. This guarantees both that the individual comparison would have p<.05 and that for k comparisons within a family of possible

comparisons, the significance level for all the comparisons will sum to p<.05.

For example, when comparing males and females only one comparison is possible. In this

family, k=1, and there is no need to adjust the significance level. When students are divided into

five racial/ethnic groups and all possible comparisons are made, then k=10 and the significance

level for each test within this family of comparisons must be p<.05/10, or p<.005. The formula

for calculating family size (k) is as follows:

k = j j ( ) −1

2 (3)

Where j is the number of categories for the variable being tested. For example, in the case of a

variable with five categories such as race/ethnicity, one substitutes 5 for j in equation 3:

k = 5 5( ) −1

2 =10

 

36Ibid.
Appendix C—Technical Notes and Methodology

70

Adjustment of Means to Control for Covariation Among Several Variables

Tabular results are limited by sample size when attempting to control for the multiplicity of

factors that may account for the variation observed between two variables. For example, when

examining the average number of credits completed, it is impossible to know to what extent the

observed variation is due to socioeconomic status (SES) differences and to what extent it is due

to differences in other factors related to SES, such as type of institution attended, intensity of enrollment, and so on. However, if a nested table were produced showing SES within type of institution attended, within enrollment intensity, the cell sizes would be too small to identify the

patterns. When the sample size becomes too small to support controls for another level of variation, one must use other methods to take such variation into account.

To overcome this difficulty, multiple linear regression was used to obtain means that were

adjusted for covariation among a list of control variables.37 Adjusted means for subgroups were

obtained by regressing the dependent variable on a set of student and enrollment characteristics.

Substituting ones or zeros for the subgroup characteristic(s) of interest and the mean proportions

for the other variables results in an estimate of the adjusted mean for the specified subgroup,

holding all other variables constant. For example, consider a hypothetical case in which two variables, race/ethnicity and SES, are used to describe an outcome, Y (such as the number of credits

completed). The variables race/ethnicity and SES are recoded into dummy variables:

Race/ethnicity R

Black, non-Hispanic 1

All others 0

and

SES S

Low SES 1

All others 0

The following regression equation is then estimated from the correlation matrix output from the

DAS:

∧

Y = a + b1R + b2S (4)

 

37For more information about weighted least squares regression, see Michael S. Lewis-Beck, Applied Regression: An Introduction, Vol. 22 (Beverly Hills, CA: Sage Publications, Inc, 1980); William D. Berry and Stanley Feldman, Multiple Regression in

Practice, Vol. 50 (Beverly Hills, CA: Sage Publications, Inc., 1987)
Appendix C—Technical Notes and Methodology

71

To estimate the adjusted mean for any subgroup evaluated at the mean of all other variables, one

substitutes the appropriate values for that subgroup’s dummy variables (1 or 0) and the mean for

the dummy variable(s) representing all other subgroups. For example, suppose we had a case

where Y was being described by race/ethnicity (R) and SES (S), coded as shown above, and the

means for R and S are as follows:

Variable Mean

R 0.109

S 0.282

Suppose the regression equation results in:

∧

Y = 51.07 + (17.63)R + (-22.46)S

To estimate the adjusted value for black students, one substitutes the appropriate parameter values into equation 4.

Variable Parameter Value

a 51.07 —

R 17.63 1.000

S -22.46 0.282

This results in:

∧

Y = 51.07 + (17.63)(1) + (-22.46)(0.282) = 62.37

In this case, the estimated mean number of credits is 62.37 and represents the expected outcome

for non-Hispanic black students who resemble the average student with respect to the other variables in the model (in this example, SES).

It is relatively straightforward to produce a multivariate model using the DAS, since one of

the DAS output options is a correlation matrix, computed using pairwise missing values and

properly weighted to account for the complex sample design and for nonresponse.38 This matrix

can be used by most statistical software packages as the input data for least-squares regression.

That is the approach used for this report, with an additional adjustment to incorporate the com-

 

38Although the DAS simplifies the process of making regression models, it also limits the range of models. Analysts who wish to

use other than pairwise treatment of missing values or to estimate probit/logit models (the most appropriate for models with categorical dependent variables) can apply for a restricted data license from NCES. See John H. Aldrich and Forrest D. Nelson, Linear Probability, Logit and Probit Models (Quantitative Applications in the Social Sciences, Vol. 45) (Beverly Hills, CA: Sage

University Press, 1984).
Appendix C—Technical Notes and Methodology

72

plex sample design into the statistical significance tests of the parameter estimates (described

below).

Most statistical software packages assume simple random sampling when computing standard errors of parameter estimates. Because of HS&B’s complex sample design, this assumption

is incorrect. A better approximation of the standard errors is to multiply each standard error by

the average design effect of the dependent variable (DEFT), where the DEFT is the ratio of the

true standard error to the standard error computed under the assumption of simple random sampling. It is calculated by the DAS and produced with the correlation matrix.