|
Items in cart [1] |
Questions? Call 888-624-8373 |
| Copyright © 2009. National Academy of Sciences. All rights reserved. Terms of Use and Privacy Statement |
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page R1
0N TI~E T0 THE DOCTORATE
A Study of the Increased Time
to Complete Doctorates
in Science and Engineering
Howard luckman
Susan Coyle
Span Bee
~0~ ACHES Pat
Washing10n, O.C. 1990
OCR for page R2
NOTICE: lbe project that is the subject of this report was approved by the Governing Board
of the National Research Council, whose members are drawn from the councils of the
National Academy of Sciences, the National Academy of Engineering, and the Institute of
Medicine. The survey project is part of the program of the Office of Scientific and
Engineering Personnel (OSEP).
This report has been reviewed by a group of persons other than the author according to
procedures approved bv a Report Review Committee consisting of members of the National
~ - r ~ ~ v
Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of
distinguished scholars engaged in scientific and engineering research, dedicated to the
furtherance of science and technology and to their use for the general welfare. Upon the
authority of the charter granted to it by the Congress in 1863, the Academy has a mandate
that requires it to advise the federal government on scientific and technical matters.
Dr. Frank Press is president of the National Academy of Sciences.
The National Academy of Engineering was established in 1964, under the chatter of the
National Academy of Sciences, as a parallel organization of outstanding engineers. It is
autonomous in its administration and in the selection of its members, sharing with the
National Academy of Sciences the responsibility for advising the federal govemment. The
National Academy of Engineering also sponsors engineering programs aimed at meeting
national needs, encourages education and research, and recognizes the superior achievements
of engineers. Dr. Robert M. White is the president of the National Academy of Engineering.
The Institute of Medicine was established in 1970 by the National Academy of Sciences
to secure the services of eminent members of appropriate professions in the examination of
policy matters pertaining to the health of the public. The Institute acts under the
responsibility given to the National Academy of Sciences by its congressional charter to be
an adviser to the federal government and, upon its own initiative, to identify issues of
medical care, research, and education. Dr. Samuel O. Thier is president of the Institute of
Medicine.
The National Research Council was organized by the National Academy of Sciences in
1916 to associate the broad community of science and technology with the Academy's
purposes of furthering knowledge and of advising the federal government. Functionin& in
accordance with general policies determined by the Academy, the Council has become the
principal operating agency of both the National Academy of Sciences and the National
Academy of Engineering in providing services to the government, the public, and the
scientific and engineering communities. The Council is administered jointly by both
Academies and the Institute of Medicine. Dr. Frank Press and Dr. Robert M. White are the
chairman and vice-chairman, respectively, of the National Research Council.
This report is based on research conducted by OSEP, with the support of the National
Science Foundation, under NSF Contract No. PRA-87 19855. Opinions, findings,
conclusions, or recommendations expressed in this publication are those of the authors and
do not necessarily reflect the view of the sponsoring agencies.
Library of Congress Catalog Card No. 89-62949
Intemational Standard Book Number 0-309-04085-X
Additional copies of this report are available from:
S010
Printed in the United States of America
National Academy Press
2101 Constitution Avenue, N.W.
Washington, D.C. 20418
OCR for page R3
PREFACE
A need exists for better models of what contributes to changes in the
time that students take to complete the doctorate. Although time to the
doctorate has been studied by Abedi and Benkin (1987), Berelson (1960), Prior
(1962), and Wilson (1965), none of these studies are based on a causal model of
student decisionmaking, and none consider the role of market forces in student
decisions. The data presented in Chapter 1 suggest that time to the doctorate in
science and engineering fields has been lengthening since 1967- in some fields,
by as much as two years. Furthermore, it is anticipated that the lengthening
mend will persist, at least into the near future, and have unfortunate consequences
because of the decline in the college-age population and the dramatic increase
expected in the number of job openings in the academic sector in the 1990s. In
response, public policy makers are likely to become increasingly concerned with
identifying and understanding ways to augment the supply of new doctorates.
While shortages of this type are not expected for a few years, it is useful now to
determine whether policies can be adopted that can limit or reverse the trend
toward longer completion times in the science and engineering fields. Existing
studies do not provide the information needed by policy makers to detains
whether public policy could, or should, alter completion times sufficiently to
slow or reverse the trends discussed in Chapter 1, or whether any policies can
have a major impact on supply in the impacted fields.
The purposes of the present study are to render an in-depth analysis of
what has happened to completion times since 1967, to provide a time-series data
base for the period 1967-1986, and to develop a model that explains some of the
factors that have caused an elongation to occur. This study looks at the effects
of changes in five types of variables: family background characteristics, student
attributes, financial aid, institutional environment, and market forces. Using
data from the Doctorate Records File and the Survey of Doctorate Recipients
maintained by the Office of Scientific and Engineering Personnel (OSEP) of the
National Research Council and from other data sources,* the study develops a
model to explain changes in both total time to the doctorate (TTD) and in the
* A more detailed description of the data from these sources is available on
request from the National Research Council, Office of Scientific and Engineering
Personnel.
iii
OCR for page R4
several components of time to the doctorate. The model is then applied to 11
scientific and engineering fields: chemistry; physics and astronomy; earn,
atmospheric, and marine sciences; mathematical sciences (including computer
and information sciences); engineering; agricultural sciences; biological sciences;
health sciences; psychology; economics; and all other social sciences.
This report is organized as follows. Chapter 1 begins with an
examination of how and when time to the doctorate has been lengthening,
illustrated by the rise in mean AD from 1967 to 1986 in each of the 11 fields.
Three components of AD are introduced, and the mean values for each are
presented and discussed. In addition, time coefficients allow one to contrast the
way in which time to the doctorate has changed during the period, and two
patterns of change are identified. Finally, quantitative estimates are provided of
the person-year losses that society has incurred from the lengthening of
completion time during this period. Chapter 2 reviews five avenues of inquiry
in the literature as they relate to time to the doctorate and models of student
decisionmaking. Chapter 3 introduces a causal model of the determinants of
T1D based on an opportunity-cost framework of student decisionmaking. The
role of financial aid and of market forces is explored in this context. Chapter 4
presents selected data on the zero-order correlations between the independent
variables in the model and lend (and its components). The correlations among
the salary variables and unemployment/employment plans variables are
discussed, and the contribution of each major vector (e.g., family background and
student attributes) is examined. Chapter 5 introduces the statistical model and
presents a summary of which regression coefficients are significant (and of their
signs) for alternative specifications of the model. Several variants of the model
are introduced to explore the effects of alternative measures of the key variables.
Chapter 6 presents the regression coefficients for the basic model and several
variants using registered time to the doctorate (RTD) as the dependent variable.
Finally, Chapter 7 discusses the findings in this study, their implications, and
research questions that warrant further study.
In addition, an extensive bibliography of readings on the determinants
of student decisionmaking is provided (pp. 107-111~. Appendix A (pp. 113-173)
provides additional tables about (1) the components of HID, (2) the person-year
losses resulting from a lengthening of Fold, (3) variables in the model, (4) zeros
order correlations among the independent variables, (5) several equations for
estimating HID, and (6) median total time to doctorate for the population as a
whole and for selected demographic groups. Finally, acronyms used throughout
this report are listed in Appendix B (pp. 175-177~.
Staff
Howard Tuckman, consultant
Susan Coyle, staff officer
1V
Yupin Bae, research associate
Linda S. Dix, editor
OCR for page R5
CONTENTS
EXECUTIVE SUMMARY
Findings
Conclusions
1 WHAT HAS BEEN HAPPENING TO TIME
TO THE DOCTORATE?
Components of Time to the Doctorate and How They lIave Changed
Through Time
The Several Kinds of Time
Mean Total Time to the Doctorate
Mean Time Spent Prior to Graduate School Enhance
Mean Registered Time to the Doctorate
Mean Time Spent Away Tom the University
Summary
The Nature and Significance of the Time Trend
The Two Models
Patterns of Change
The Shape of Change
Manpower Loss from Lengthening Total Time to the Doctorate
2 MODELS OF THE FACTORS THAT AFFECT STUDENT
CHOICE AND TIME TO THE DOCTORATE: A
LITERATURE SURVEY
Literature on Persistence and Attntion
Literature on Educational Aspirations
Literature on Enrollments
Literature on Expected Returns
Literature on TTD
Summary
3 A MODEL OF THE DETERMINANTS OF TTD
The Model
The Critical Role of Opportunity Costs
v
1
4
7
8
8
9
12
12
12
13
13
13
14
19
19
25
25
28
29
31
32
33
35
35
36
OCR for page R6
Financial Aid and Its Impact on Completion Times
The Impact of Type of Aid
Effects on He Components of AD
Market Forces and Completion Times
Effects of Changes in Relative Salaries
Effects of Employment Opportunities
Effects on the Components of 1TD
The Variables Used to Develop He Model
THE RELATION BETWEEN THE FIVE VECTORS
OF VARIABLES AND TTD AND ITS COMPONENTS:
A COMPARISON OF ZERO-ORDER CORRELATIONS
The Importance of Disaggregation by Field
Changes in Family Background Characteristics
Changes in Student Attributes
Changes in Tuition and Financial Aid
Changes in Institutional Environment
Changes in Market Forces
Salary Variables
Employment Indicator Variables
The Stock Variable
The Zero-Order Correlation of the Vectors
Summary
5 CHANGES IN TTD
Common Variables Model
Log Linear Equations
Weaknesses of the Common Variables Model
Unique Variables Model
Summary of Findings
Limitations of the Analysis
What Can Be Learned from He Findings?
6 CHANGES IN REGISTERED TIME TO THE DOCTORATE
TIME PRIOR TO GRADUATE ENTRANCE,
AND TIME NOT ENROLLED IN THE UNIVERSITY
Registered Time to the Doctorate
RTD in the Common Variables Model Using Linear
and Log Linear Equations
RTD in the Unique Variables Model
Evaluation of the Results
Time Spent Prior to Graduate School Entrance (TPGE)
Time Not Enrolled in the University (TNEU)
Summary of the Findings
V1
38
38
39
41
41
42
43
43
45
45
46
46
51
51
56
56
60
60
65
67
69
69
71
71
71
71
73
77
79
79
79
79
81
85
87
89
OCR for page R7
7 PAST AS PROLOGUE
What Has Happened to Time to the Doctorate?
Total Time to the Doctorate
Registered Time to the Doctorate
Variation Around the Mean
Could Changes in I-POE and TNEU Have Been Large Enough
to Explain the Change in TTD?
Possible Explanations
Epistemic Explanations
Institutional Explanations
Student Preference-Based Explanations
Financial Need-Based Explanations
Demographic and Ability-Based Explanations
Mbrket-Based Explanations
Is There A Single Explanation for Increase in TTrL,?
Implications of a Continuing Rise in TTD
A More Resource-Intensive Doctoral Program
A Longer Gestation Period
Increased Attntion
Lower Returns for Graduate Study
Changes in the Attractiveness of Alternative Doctorate Careers
i~~ as a Policy Instrument
SELECTED BIBLIOGRAPHY
APPENDIXES
A Related Tables
B List of Acronyms
LIST OF TABLES
1.1 The Relationship Between the Several Time Measures
1.2 Estimated Time Trends in Mean Total Time to Doctorate
1.3 Estimated Time Trends in Mean Registered Time to Doctorate
1.4 Estimated Time Trends in Mean Time Prior to Graduate Entrance
1.5 Estimated Time Trends in Mean Time Not Enrolled in University
1.6 Difference Between Forecast and Actual TiDs, 1987
1.7 Maximum Potential Person-Years Loss Resulting from Lengthening
Total Time to the Doctorate, 1968-1986
93
93
93
94
95
96
97
97
97
98
99
100
101
101
102
102
103
104
105
105
105
107
113
115
175
9
15
16
17
18
22
22
3.1 Mean Time to the Doctorate, by Primary Source of Support,
1986 and 1987 40
4.1 Correlation for Percent Married, 1967-1986 47
4.2 Correlation for Average Number of Dependents, 1967-1986 47
4.3 Correlation for Percent Black, 1974-1986 48
4.4 Correlation for Percent Hispanic, 1974-1986 48
. .
V11
OCR for page R8
Correlation for Percent Female, 1967-1986
Correlation for Average Age at Start of Doctoral Program,
1967-1986
4.7 Correlation for Percent From Selective Undergraduate Schools,
1967-1986
Correlation for Percent with Undergraduate Degree in Doctoral Field,
1974-1986
4.9 Correlation for Average Tuition Paid
4.10 Correlation for Percent with Primary Support from Federal
Government, 1967-1986
4.11 Correlation for Percent with Primary Support from Private
Foundations, 1967-1986
Correlation for Percent with Primary Support from Research
Assistantships, 1967-1986
Correlation for Percent with Primary Support from Teaching
Assistantships, 1967-1986
4.14 Correlation for Percent with Primary Support from Own Eamings,
1977-1986
4.15 Correlation for Percent with Baccalaureate from Foreign
Institutions, 1967-1986
4.16 Correlation for Number of Full-Time Equivalent Faculty
4.17 Correlation for Government R&D Spending
4.18 Correlation for Percent with Baccalaureate from Category I
- Research University, 1967-1986
4.19 Correlation for Percent with Baccalaureate from "Top 40" School,
1967-1986
Correlation for Percent with Graduate Degree from Category I
or Category II Research School, 1967-1986
Correlation for Percent with Graduate Degree from "Top 40"
School, 1967-19g6
Correlation for Average Salary of Recent Doctorate Recipients
Correlation Between SALRAT1 and rl~l L) and Its Components
Correlation for Salary Ratio of Doctorates 10 Years After Degree
Correlation Between SDR Salaries and Salaries Reported by Other
Sources, 1968-1986
Correlation for Percent Seeking Postgraduate Employment
Correlation for Percent with Dehlnite Employment
or Postdoctoral Appointment
Correlation for Overall U.S. Unemployment Rate
Correlation for Unemployment Rate of College-Educated
Population
. . .
vail
49
49
50
50
51
52
52
53
53
54
54
55
55
57
57
58
58
59
59
60
61
62
62
63
63
OCR for page R9
4.30 Correlation Between Percent Seeking Postgraduate Employment
and the Other Market Variables
4.31 Correlation for Per Capita Number of Doctorates in the
United States, 1967-1986
4.32 Amount of Adjusted Variation in TTD Explained by Each
of the Five Vectors
4.33 Number of Fields in Which Each Vanable Had a Statistically
Significant Correlation with TTD or RTD
5.1 Summary of Common Linear Model Regression Results
for TTD, by Variable
5.2 Summary of Common Log-Linear Model Regression Results
for TTD, by Variable
5.3 Summary of Unique Variables Model Regression Results
for TTD, by Field
5.4 Number of Fields in Which Variable Has Statistically
Significant Effect on I-l L,
6.1 Summary of Common Linear Model Regression Results
for RTD, by Field
6.2 Summary of Common Log-Linear Model Regression Results
for RTD, by Field
6.3 Summary of Unique Variables Model Regression Results
for RTD, by Field
6.4 Number of Fields in Which Variable Has Statistically
- Significant Effect of TTD
6.5 Summary of Common Linear Model Regression Results
for TPGE, by Variable
6.6 Summary of Common Log-Linear Model Regression Results
for TPGE, by Variable
6.7 Summary of Common Linear Model Regression Results
for TNEU, by Variable
6.8 Summary of Common Log-Linear Model Regression Results
for TNEU, by Field
7.1 Median Total Time to the Doctorate Over Time
LIST OF FIGURES
Median years to the doctorate, all fields combined including
humanities and education fields, 1958-1986
Components of mean total years to the doctorate, by field,
1967 and 1986
Mean total time to the doctorate, by field, 1967-1986
1X
64
64
65
66
70
72
74
76
80
81
82
84
86
88
89
90
94
7
10
20
OCR for page R10
