Empirical papers
written collaboratively with colleagues are listed here
in reverse chronological order and can be downloaded
by clicking on their titles. I have grouped them loosely, by substantive
area:
Using
a unique data set providing longitudinal achievement data
on a large sample of students who attended public or private
elementary schools in Bogotá, Colombia, we examine
the roles of teacher quality, class size, peer groups, and
governance structure in predicting why, net of family background
and prior achievement, the average achievement of children
in some classrooms is higher than that of children in other
classrooms.
Uses NLSY data
to examine whether measures of the skills of male teenagers
predict their wages at ages 27 and 28. The effects of three
types of skills are examined: academic skills, skill at completing
elementary mental tasks quickly and accurately, and self-esteem.
The results show that all three types of skills play roles
in predicting subsequent wages but the different skills are
of differing importance in explaining gaps between the average
wages of White males and those of Black and Hispanic males.
Uses two
longitudinal datasets from the mid-1980s and early 1990s
(NLS72 and HS&B) to investigate how
important teenagers' cognitive skills are in predicting subsequent
labor-market success. The paper shows that the same evidence
can be used to support the claim that cognitive skills are
important determinants of subsequent earnings, and that the
effect of cognitive skills is modest. It also shows that
while some evidence indicates that college pays off more
for students who enter with strong cognitive skills than
for students who enter with weaker skills, the bulk of the
evidence does not support this conclusion.
Uses NLSY data
to investigate the educational opportunities pursued by young
women who drop out of high school. All of the educational
investments enhance earned income markedly but, for the average
woman, the increase in earnings is not enough to lift a family
out of poverty.
Examines
the value of the GED credential and the conventional
high-school diploma in explaining the earnings of 27-year-old
males in the early 1990s, using the HS&B Sophomore
cohort. The findings of prior studies, which assume that
the labor market value of the GED credential does
not depend on the skills with which dropouts left school,
are replicated. However, these average effects are shown
to mask a more complicated pattern -- obtaining a GED is
associated with higher earnings at age 27 for those male
dropouts who had very weak cognitive skills as 10th graders,
but not for those who had stronger cognitive skills.
Explores
whether the labor market rewards cognitive skill differences
among high-school dropouts, using a dataset that provides
information on the universe of dropouts who last attempted
the GED examinations in Florida and New York in
1989 and 1990. Results indicate substantial earnings returns
to cognitive skills for all groups except White male dropouts.
This paper
tests the labor market signaling hypothesis for the General
Educational Development (GED) equivalency credential. Using
a unique data set containing GED test scores and Social Security
Administration (SSA) earnings data, we exploit variation
in GED status generated by differential state GED passing
standards to identify the signaling value of the GED, net
of human capital effects. Our results indicate that the GED
signal increases the earnings of young white dropouts by
10 to 19 percent. We find no statistically significant effects
for minority dropouts.
Uses longitudinal
data from the NLSY to investigate whether the wage
trajectories of male high school dropouts are affected by the
acquisition
of the GED, by postsecondary education and by training. We
find that acquisition of the GED results in wage increases
for dropouts who left school with weak skills, but not for
dropouts who left high school with stronger skills. College
and training provided by employers are assocatiated with higher
wages for male dropouts.
Uses longitudinal
data from the NLSY to investigate how school dropouts'
acquisition of a GED affected the probability that
they would obtain training, post-secondary education, or
military service. We use longitudinal data to estimate prototypical
training and education profiles, and find that the probability
that a dropout participated in post-secondary education or
non-company training was greater after GED receipt
than before, for both men and women. Still, less than half
of GED recipients received post-secondary education
or training by age-26.
Uses longitudinal NLSY data
to study whether male high-school dropouts' trajectories
of wages, annual number of hours worked, and annual earnings
are affected by acquisition of the GED credential.
We find that acquisition of the GED is associated
with an increase in the rate of wage growth. Our findings
are consistent with the hypothesis that some dropouts, after
obtaining a GED, search for a better paying job
or enter a training program.
Uses the
sophomore cohort of HS&B to investigate the
roles that race, ethnicity, and academic skills play in predicting
whether high-school students persist along each of the various
steps of the path into teaching. We show that the challenge
of creating a racially and ethnically diverse teaching force
is not primarily one of influencing the occupational decisions
of minority college graduates. Instead, the critical challenge
is to increase the high-school graduation, college enrollment
and college graduation rates of minority youth.
We use median-detrends
and schematic plots to detect and document an influence on
the duration of teacher employment which has heretofore eluded
empirical quantification -- the involuntary layoff. Using data
on the lengths of employment of about 14,000 teachers hired
between 1969 and 1981 in St. Louis, we show that over and above
the effects that previous researchers have identified, there
were certain years in which many more recently hired teachers
were likely to leave their districts thatn might have been
expected.
Investigation
of the career paths of White Teachers in North Carolina who
were first hired between 1976 and 1979. Using discrete-time
hazards-modeling, we explore the relationship between the risk
of leaving teaching and teacher salary and opportunity cost.
We discuss implications of the findings for policy and teacher
supply.
We use median-detrends
and schematic plots to detect and document an influence on
the duration of
teacher employment which has heretofore eluded empirical quantification
-- the involuntary layoff. Using data on the lengths of employment
of about 14,000 teachers hired between 1969 and 1981 in St.
Louis, we show that over and above the effects that previous
researchers have identified, there were certain years in which
many more recently hired teachers were likely to leave their
districts thatn might have been expected.
Attempts
to determine whether enough qualified teachers will be available
to staff the nation's schools in the coming years have been
hampered by methodological difficulties that are inherent in
the study of teacher career patterns, using proportional hazards
modeling. We find that teacher demographic characteristics
and subject specialty are important predictors of the length
of stay in teaching. The results call into question several
assumptions about teacher career persistence implicit in the
national teacher supply and demand model.
Analyzes
changes in teacher salary schedules of Michigan school districts
between 1970 and 1980. We find that starting salaries, expressed
in 1970 dollars, decreased by an average of 20% over the
decade. Real maximum salaries decreased by 15%. The between-district
variablity of starting salaries also increased markedly over
the decade, making the average starting salary a much poorer
estimate of the starting salary a particular teacher earned
in 1980 than in 1970. The between-district variability of
maximum salaries did not increase over the decade.
III.
Medicine and Psychology, Psychiatry (Back
to top)
Investigation
of stability and change in personality disorders from
an individual growth curve perspective. The PD features of 250
subjects were examined
at 3 different time points using the International
Personality Disorders Examination over a
4-year period. The study provides
compelling
evidence of change in PD features over time, and does
not support the assumption that PD features are traitlike,
enduring, and stable over time.
