Male white-black wage gaps, 1979-1994: a distributional analysis.
Rodgers, William M., III
1. Introduction
Numerous studies show that during the 1980s the mean white-black
wage gap among new entrant (0-10 years of potential experience) males
expanded. (1) Juhn, Murphy, and Pierce (1991; JMP) attribute the mean
gap's expansion to a widening of the overall U.S. wage distribution
caused by a host of economy-wide race-neutral changes that led to labor
demand shifts toward better-educated and better-skilled workers
regardless of race. Because African Americans tend to be at lower levels
of the overall skill distribution, the shifts adversely impacted African
American men more than white men, leading to an expansion in the mean
wage gap.
To arrive at this conclusion, JMP decompose the expansion in the
mean new entrant wage gap into four components. The first two components
measure the wage gap's increase because of a widening in observable racial differences in measured characteristics and their prices--for
example, educational attainment and the returns to education. The third
component captures the contribution of growing racial discrimination and
widening differences in unmeasured skills to the wage gap's
expansion. This term's contribution is measured by the drop in the
mean percentile rank of blacks in the white residual wage distribution.
The fourth component identifies the role of increases in the prices of
unmeasured skills and is measured by the increase in the variance of the
white residual wage distribution.
When applied to the March Annual Demographic files of the Current
Population Survey, JMP find that from 1979 to 1987 increases in the
price of unmeasured skills explain all of the new entrant mean wage
gap's expansion, indicating that factors that adversely impacted
less-skilled workers regardless of race are the primary cause of the
wage gap's expansion.
In related work, Reardon (1997) uses a national sample of white and
African American men from the 1980 and 1990 decennial censuses and shows
that the mean racial wage gap's expansion is caused by increased
variance in the distribution of residual wages, generated by labor
demand shifts toward high-skilled whites and away from medium-skilled
whites and high-skilled African American men. The wage gap expands
because high-skilled African American men earn wages that are similar to
those of whites in the middle and upper third of their wage
distribution. The labor demand shifts led to a stretching or increased
variance in the wage distribution that favored high-skilled whites
relative to high-skilled African Americans and medium-skilled whites.
This paper makes several contributions to the literature on racial
wage gaps and the technical literature on wage decompositions. First, I
examine whether JMP's (1991) results hold up when the analysis is
disaggregated by experience and educational attainment. This is an
important extension for two reasons. Bound and Freeman (1992), Rodgers
(1997a), and others have found that the racial wage gap among high
school graduates, and particularly among college graduates, expanded
significantly after the late 1970s. Over the same time period, the
variance of wages within these educational categories increased. Second,
it is important to determine the extent to which racial inequality that
was generated while a cohort was a new entrant persists as it ages.
The paper's technical innovation is the development of a
distribution or skill-specific decomposition that identifies whether the
stretching of the white wage distribution uniformly contributes to an
expansion in racial inequality at all skill levels or quantiles of the
wage distribution, or whether the contribution of the wage
distribution's stretching is specific to a skill level. For
example, does the increase in the price of unmeasured skills explain a
greater portion of the increase in the racial wage gap between
high-skilled African Americans and whites than it does between
medium-skilled African Americans and whites?
An additional benefit of the skill-specific decomposition is its
ability to address the concerns outlined in Seun (1997). If the fall in
the position of the average black in the white distribution is
correlated with a stretching of the white wage distribution, the JMP
decomposition overstates the importance of the prices of unmeasured
skills in explaining the mean white-black wage gap's expansion. It
understates the role of unobservable skills. The bias is because of the
fact that when wage inequality expands, "the mean percentile rank
of low-wage groups will rise simply because more dispersed distributions
have thicker tails" (Seun 1997, p. 560). Decomposing the change in
the wage gap at specific skill levels or quantiles, for example, the
median, should weaken this relationship and yield unbiased estimates of
each component's contribution to changes in racial wage inequality.
The third contribution of this paper is to explore whether
JMP's results generalize to another data source. Instead of using
the Current Population Survey (CPS) March Annual Demographic files as
JMP do, I use the CPS Outgoing Rotation Group (ORG) files. The benefit
of using the ORG files is that they contain three times the number of
individuals as do the CPS March Annual Demographic files, thus allowing
for more precise within-group, for example, categories of educational
attainment or wage gap estimates. Further, the ORG files contain direct
measures of hourly and weekly wages and of usual hours worked per week.
This lessens the measurement error that may be present in hourly and
weekly wages constructed from the March files' data on annual
earnings and on hours and weeks worked. The ORG is not without
disadvantages. The data are first available for 1979. However, this
presents no problem because prior to 1979, JMP find that the wage gap
narrowed. (2) My primary focus is on the period of the wage gap's
expansion, the first half of the 1980s.
The paper's findings can be summarized as follows. From 1979
to 1985, the mean white-black wage gap among new entrant men in the ORG
data expanded. A JMP decomposition of the wage gap's expansion
indicates that it is best explained by an increase in the prices of
unmeasured skills and a decline in the relative position of blacks in
the white wage distribution. From 1985 to 1994, the mean wage gap among
new entrants continued to expand. JMP decompositions indicate that the
expansion is best explained by a relative worsening in the observable
characteristics of African Americans and an increase in the prices of
unmeasured skills. These adverse changes more than offset the
improvement of the mean black in the white residual wage distribution.
For older men, the mean wage gap exhibits a different pattern. From
1979 to 1985, the mean wage gap remained the same. From 1985 to 1994,
the period during which new entrants moved into the older male category,
the gap expanded. This pattern suggests that the racial inequality that
emerged within the cohort of new entrants who entered the labor market in the early 1980s continued to expand as they aged.
The distributional decompositions yield similar findings to those
in Reardon. From 1979 to 1985, increased variance in new entrant wages
explains racial inequality's expansion among medium-and
higher-skilled new entrant blacks and whites. The decomposition of the
change in the median white-black wage gap probably provides the best
estimate of the contribution of increased variance in wages to the
white-black wage gap's expansion. Unlike the decompositions of the
changing gaps at the distribution's tails, the median decomposition
is less sensitive to the potential dependence of increases in the prices
of unmeasured skills and percentile ranks.
Among older men, the median decomposition indicates that increased
variance explains none of the wage gap's widening. The
decompositions of the gaps at the tails of the distribution indicate
that increased variance plays a role in the wage gap's expansion,
but are probably biased because of the dependence of increases in the
prices of unmeasured skills and percentile ranks of blacks in the white
residual wage distribution. For example, increased variance overpredicts
the actual wage gap's expansion among less-skilled older men.
Within categories of educational attainment, increased variance
plays a minor role in contributing to growing racial wage inequality,
especially among black and white college graduates.
The paper proceeds as follows. Section 2 describes the methodology.
Section 3 describes the data. Section 4 presents the results. Section 5
summarizes the main results and relates them to the literature on
white-black wage gaps.
2. Methodology
In this section, I first describe the regression specifications
used to estimate white-black wage gaps at the mean and quantiles, for
example, the median, in the distribution. Second, I summarize the JMP
mean-based wage decomposition technique and Seun's (1997) argument
as to why the meanbased decomposition leads to an upward bias in the
contribution of rising inequality to increases in the wage gap, and then
describe the distribution-based decomposition technique that I
developed.
To estimate the regression-adjusted mean white-black wage gap in
other words, the residual gap, researchers typically write the model for
the ith individual in year t as:
(1) E([y.sub.i]|[X.sub.i], [R.sub.i]) = [X'.sub.i][beta] +
[R.sub.i][gamma],
where [y.sub.i] is the ith individual's log wage, [X.sub.i] is
a k x 1 vector of predictor variables for the ith individual, [R.sub.i]
is a race indicator variable that equals 1 if the individual is white
and 0 if the individual is black, and [beta] and [gamma] give the
coefficients on these variables. The notation E(y|X, R) denotes the mean
of the conditional distribution of y given X and R.
To estimate the regression-adjusted white-black wage gap at various
quantiles, for example, the median, of the wage distribution in year t,
the basic quantile regression model introduced in Koenker and Bassett (1978, 1982), and further developed by Powell (1984, 1986) is used.
(3,4) More recently, Buchinsky (1998) provides a detailed discussion of
the practical issues related to estimating quantile regressions. The
model for the ith individual may be written as
(2) [Quant.sub.q]([y.sub.i]|[X.sub.i], [R.sub.i]) =
[X'.sub.i][[beta].sub.q] + [R.sub.i][[gamma].sub.q],
where [[beta].sub.q] and [[gamma].sub.q] give the coefficients on
the variables for the qth quantile. (5) The notation [Quant.sub.q](y|X,
R) denotes the qth quantile of the conditional distribution of y given X
and R. For example, if q equals 0.50, [[gamms].sub.q] measures the
white-black wage gap at the median and [Quant.sub.0.50](y|X, R) denotes
the median of the conditional distribution of y given X and R.
Equations 1 and 2 are used to estimate regression-adjusted mean and
median wage gaps for 1979 to 1994. The specification comes from Bound
and Freeman (1992). Education is linear until 7 completed years, and
then is unconstrained from 8 to 18. Specifically, [X.sub.i] contains an
education variable that takes the actual value of education if it is
less than 8, and 0 if education exceeds 7, and the following dummy
variables: [less than or equal to] 8, 9, 10, 11, 13, 14, 15, 16, 17, and
18. Respondents with 12 completed years of schooling are the excluded
group. Dummy variables for individual years of potential experience and
region of residence are included in [X.sub.i]. (6)
The specification used to estimate Equation 2 in the
distributional-specific decomposition of changes in the white-black wage
gap among subgroups (e.g., new entrant high school graduates) lets
[X.sub.i] contain dummy variables for high school graduate (years of
schooling = 12) and college graduate (years of schooling [greater than
or equal to] 16), with high school dropouts (years of schooling < 12)
as the excluded group. (7) For new entrants, I include a dummy variable
that equals 1 if potential experience is 1 to 10 years, and 0 if
potential experience is 11 to 20 years. I use this more parsimonious specification because these categories, particularly those with less
than 10 years of potential experience, are the typical subgroups that
JMP and others examine. I also use this specification because it reduces
slightly the computational costs associated with bootstrapping the
standard errors.
To decompose the residual gap into two components--changes in
discrimination and/or changes in racial differences in unobservable
skills, and changes in white wage inequality--JMP start by estimating
Equation 1 for whites in year t: (8)
(3) E([y.sub.iwt]|[X.sub.iwt]) = [X'.sub.iwt][[beta].sub.t].
The residual, which is assumed to have mean zero and variance one,
is rewritten as the product of a standardized normal [[theta].sub.it]
variate and the residual standard deviation of white male wages for the
regression [[sigma].sub.t]. The actual wage gap between white and
African American men in year t is then
(4) [D.sub.t] = [y.sub.wt] - [y.sub.t] =
[DELTA][X.sub.t][[beta].sub.t] + [[sigma].sub.t][DELTA][[theta].sub.t],
where [DELTA][[theta].sub.t] [equivalent to] [[theta].sub.wt] -
[[theta].sub.bt] [equivalent to] - [[theta].sub.bt] [equivalent to]
[[epsilon].sub.bt]/[[sigma].sub.t]. The term [DELTA][[theta].sub.t]
denotes the difference in the average standardized residuals of white
and black males. The decomposition can be repeated for a second year
t'. A narrowing or widening in the white-black wage gap from year t
to t', can be written as
(5) [D'.sub.t] - [D.sub.t] = ([DELTA][X.sub.t'] -
[DELTA][X.sub.t])[[beta].sub.t] +
[DELTA][X.sub.t']([[beta].sub.t'] - [[beta].sub.t]) +
([DELTA][[theta].sub.t'] -
[DELTA][[theta].sub.t'])[[sigma].sub.t] +
[DELTA][[theta].sub.t']([[sigma].sub.t'] - [[sigma].sub.t]).
Equation 5 decomposes the change in the actual wage gap into four
components:
(1) changes in measured characteristics holding the coefficients or
prices fixed, ([DELTA][X.sub.t'] - [DELTA][X.sub.t])[[beta].sub.t]
(2) changes in prices holding characteristics fixed,
[DELTA][X.sub.t']([[beta].sub.t] - [[beta].sub.t])
(3) the contribution of shifts in central tendency, or the movement
of the average black in the white distribution,
([DELTA][[theta].sub.t'] - [DELTA][[theta].sub.t])[[sigma].sub.t],
(4) the contribution of shifts in spread, or changes in the
variance of wages, [DELTA][[theta].sub.t'] ([[sigma].sub.t'] -
[[sigma].sub.t]). (9)
Reporting the third and fourth terms separately shows how much of
the change in the total residual gap (components 3 and 4) is caused by
"blacks moving up or down within the distribution of whites"
for any given set of observables (component 3) and how much is caused by
general changes in wage inequality that affect blacks because their
residual wages (constructed from the white coefficients) do not have the
same distribution as whites (component 4) (JMP, p. 126). Specifically,
JMP note that if the variance in the distribution of wages is increasing
within each observable skill category, as it was during the 1980s, this
will adversely affect African Americans even in the absence of other
changes because African Americans are already concentrated in the lower
part of the earnings distribution.
The decomposition in Equation 5 contains the familiar index number
problem. I could have derived similar decompositions using different
base years or by substituting the estimated white prices with the black
prices. I use the average across all years as the base to avoid possible
extremes within any given year. Thus, the year t' terms correspond
to mean quantity differences and "white prices" across the
16-year sample.
Seun (1997) demonstrates that the JMP mean procedure generates
biased results if wage inequality and the percentile ranks are not
independent of one another. As wage inequality expands, the term that
measures the contribution of unobservable prices will increase, and the
term capturing movements in the position of blacks will fall. Seun
asserts that this problem is greatest at the tails of the distribution.
As inequality rises, the tails become fatter, artificially moving blacks
up in the white distribution. The bias will be larger at the lowest
percentiles because of the skewed shape of wage distributions, but bias
could be present at segments of the distribution where mass points
exist, wages that are common to a significant portion of the population.
To construct an unbiased estimate of the increased variance's
contribution to the white-black wage gap's expansion, I construct
the actual change in the white-black wage gap between two periods and
the predicted change in the wage gap because of increases in the price
of unobservable skills. The predicted change is the growth in the wage
gap assuming that the percentile position of blacks remains constant
over time. I then create a ratio of the predicted and actual changes. A
value of 1 indicates that the predicted change equals the actual change,
implying that the stretching of the white wage distribution at that
quantile explains all of the gap's actual change at that quantile.
To assess whether the increased variance hypothesis explains expanding
wage gaps within sociodemographic groups (e.g., new entrant college
graduates), I utilize the quantile regression model in Equation 2 to
build conditional wage distributions.
At the median, the residual wage procedure starts with estimating a
log wage equation for year t using only whites with the specification in
Equation 1. I then use the estimated coefficients to construct white and
black residual distributions. With these distributions, I find the white
residual wage that equals the median black wage. This location is
denoted as the qth quantile. Now using the year t' white residual
distribution, I find the white residual that corresponds to the qth
quantile. This residual is interpreted as the predicted year t'
black wage residual, assuming that the median black's initial year
t position is preserved. The actual change, predicted change and the
ratio of the two are then constructed.
Analytically, we can think of the procedure as follows. In year t,
we have a log wage equation for the ith white individual:
(6) E([y.sub.iw]|[X.sub.iw] = [X'.sub.iw][[beta].sub.w],
where [X.sub.iw] is a k x 1 vector containing the observable
characteristics of the ith white male, and [[beta].sub.w] gives the
coefficients on these characteristics. The ith white residual is the
following:
(7) [[epsilon]'.sub.iw] = [y.sub.iw] -
[X'.sub.iw][[beta].sub.w],
and the ith black residual, if he is paid like a white, is:
(8) [[epsilon]'.sub.ib] = [y.sub.ib] -
[X'.sub.ib][[beta].sub.w].
The median African American residual wage, Med([[epsilon].sub.b]),
is found in the African American residual wage distribution. Let
[[epsilon].sup.t.sub.b,0.5] denote the value of the year t median
African American residual wage.
Now find the quantile, [q.sup.*], where [[epsilon].sup.t.sub.b,0.5]
is located in the white residual distribution. This is where
[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.].
Using the year t' data, estimate Equation 6 for whites.
Construct the white and black residuals in Equations 7 and 8. Now find
[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.]. This is the year
t' white residual wage at the quantile [q.sup.*], or the predicted
year t' black residual wage. Also calculate
[[epsilon].sup.t'.sub.w,0.5] and [[epsilon].sup.t'.sub.b,0.5],
the year t' white and black median residual wages, respectively.
The residuals [[epsilon].sup.t.sub.w,0.5], [[epsilon].sup.t.sub.b,0.5],
[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.],
[[epsilon].sup.t'.sub.w,0.5], and [[epsilon].sup.t'.sub.b,0.5]
are used to construct the year t and t' actual gaps and the year
t' predicted median gap. They are the following:
(9) AGA[P.sub.t] = [[epsilon].sup.t.sub.w,0.5] -
[[epsilon].sup.t.sub.b,0.5],
(10) AGA[P.sup.t'] = [[epsilon].sup.t'.sub.w,0.5] -
[[epsilon].sup.t'.sub.b,0.5]
(11) [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.].
To decompose the actual gap's change, I form the ratio of the
predicted and actual changes. The ratio determines the extent to which
the expansion in the median white-black wage gap is because of increased
variance in the distribution of wages as opposed to [q.sup.*]. I also
evaluate the ratio at the 10th, 25th, median, 75th, and 90th
percentiles. (10)
(12) RATIO = PDGAP/ADGAP = PGA[P.sub.t'] -
AGA[P.sub.t]/AGA[P.sub.t'] - AGA[P.sub.t]
To assign statistical meanings to RATIO, PDGAP and ADGAP, I use
bootstrap methods to construct standard errors. (11)
Because the variance of white wages increased within categories of
educational attainment and the relative positions of black men fell
within each category, thus contributing to within group increases in the
black-white wage gap, I construct estimates of RATIO, PDGAP and ADGAP
for high school and college graduates by experience. (12)
Along with being less sensitive to the statistical artifact shown
in Seun (1997), another key difference between the distribution-specific
and the JMP technique is the assumption of a fixed distribution. The
distribution-specific decompositions use 1979 and 1985 as the base
years, whereas the JMP decomposition uses the average distribution over
all years of the sample. An obvious disadvantage to using 1979 and 1985
as the end points (base years) is that the decompositions are
potentially sensitive to this choice. As a robustness check, I perform
the distribution-specific decomposition but locate blacks in a white
distribution that pools the 1979 and 1985 distributions. (13) I obtain
qualitatively similar results.
3. The Data
The data come from the 16 consecutive CPS ORG files from 1979 to
1994. The samples consist of full-time black and white males with 0-20
years of potential experience, (14) who fit the following criteria: (i)
at least 18 years of age, (ii) Monthly Labor Force Record is either
working or on layoff, (15) (iii) employed in either the public or
private sector (excludes the self-employed), and (iv) usual hours worked
per week is greater than or equal to 35, or less than or equal to 99.
It is important to note that from 1979 to 1994, the sample sizes of
new entrant men fall. In isolation, one might attribute the fall to
sample selection, and thus use decomposition techniques developed in
Reimers (1983) and Hoffman and Link (1984) to remove the potential bias.
However, if we examine the sample sizes of older men, we see that they
increased during this period. I attribute the shifts in samples to the
movement of the baby boom generation through the 0-10 years of potential
experience category to the 11-20 years of experience category. In 1979,
there are 29,629 new entrants and 19,372 older men. By 1985, the number
of new entrants falls to 26,646, whereas the number of older men
increases to 23,412. The shifts continue until 1987, after which they
level off. After 1990, the number of new entrants and older men both
decline. This is because of the Census Bureau's switch to the 1990
decennial census on which the CPS sample is based, as well as to changes
in collection methods. (16)
The empirical analysis focuses on decomposing changes in the
white-black log hourly wage gap. (17) My results will differ from those
of JMP for several reasons. JMP decompose the change in the log weekly
wage gap, which is constructed from annual wages and salary and weeks
worked. First, measurement error may be a greater problem in their
analysis. Second, even though they restrict their samples to year-round,
full-time men, their results may still have a weeks- and hours-worked
impact imbedded in them. (18) I find in the ORG files that full-time
African American men work on average two hours less than white men, and
the difference has grown since 1979. (19) If this trend exists in JMP,
then their estimates overstate the role that increased variance in the
distribution of wages play in explaining changes in the gap. (20)
4. Empirical Results
This section first describes the broad trends in white-black wage
gaps from 1979 to 1994. Table 1 displays regression-adjusted mean and
median log hourly wage gaps for men with 0-10 and 11-20 years of
potential experience. These figures are estimates of [gamma] in
Equations 1 and 2. The timing of the changes in each experience
group's gap suggests that African Americans who entered the labor
market early in the 1980s carried their losses with them as they aged,
and that their losses continued to grow even as the macroeconomy moved
toward its peak in 1989 and recession and recovery in the early 1990s.
(21) The typical pattern of the new entrant gaps is expansion from 1979
to 1985, and narrowing from 1985 to 1994. For older men, the pattern is
the reverse, with 1985 serving as the breakpoint for both experience
groups.
Over the 16-year period of analysis, the new entrant mean and
median gaps exhibit the same pattern. From 1979 to 1985 the mean gap
expands from 10 to 15% and the median gap expands from 12 to 18%.
Although modest, both gaps narrow by 3 percentage points from 1985 to
1994. Table 1 shows that as this cohort began to comprise a larger share
of the more experienced group, the wage gaps among men with 11-20 years
of potential experience expanded. From 1979 to 1985, the mean gap
remained at 16.0%, whereas the median gap increased from 17.0 to 19.0%.
From 1985 to 1994, the gaps peaked at around 20%.
The table also displays the regression-adjusted mean and median
wage gaps by educational attainment and potential experience. The high
school dropout gaps show considerable variation from 1979 to 1994. The
gaps expand during the first half of the 1980s and narrow during the
second half of the 1980s. They continue to narrow during the early
1990s. The narrowing after 1990 is consistent with the selective
withdrawal hypothesis that a larger portion of less-skilled African
Americans lost their jobs during the 1990s recession and weak jobs
recovery. The gap's narrowing is also consistent with the increase
in the federal minimum wage having a greater impact on the relative
wages of blacks. The new entrant high school graduate gap follows the
same path as the "total" gap, expanding from 1979 to 1985 and
contracting from 1985 to 1994. The gaps among older high school graduate
men expanded slightly prior to 1985, but the growth accelerated after
1985.
The growth in the wage gap among college graduates shows the most
dramatic expansion. The gap starts out at zero in 1979 and finishes at
16.0% in 1994. During the first half of the 1980s, the mean and median
wage gaps among new entrants expanded by 3.0 and 1.0 percentage points,
respectively. From 1985 to 1994, the mean and median gap's
expansion accelerates, growing by 9.0 and 17.0 percentage points. For
older college graduate men, the gap starts the 1980s at around 10.0% and
exhibits little change through the decade's first half. It expands
by 13 percentage points from 1985 to 1994.
The important contribution of this section is the identification of
the growth in the new entrant wage gap from 1979 to 1985, the growth in
the older men's wage gap from 1985 to 1994, the dramatic expansion
of the college graduate black-white wage gap, and the suggestion that
the wage gap did not dissipate as the new entrants aged.
I now show that even when JMP's techniques are applied to the
ORG CPS files, similar results are obtained. Table 2 first presents the
positions of the 10th, 25th, median, 75th, and 90th percentile blacks in
the white residual hourly wage distribution. (22) These figures are used
to develop the third term in the JMP decomposition. The wage residuals
are constructed using education and potential experience coefficients
from the white regression line estimated in Equation 6. Each potential
experience group has its own regression line. To assign a statistical
interpretation to the positions, I use bootstrap methods to construct
standard errors. Even though this procedure and standard errors create
more information to analyze and interpret, it has the advantage of
showing whether changes in the relative positions of blacks were uniform
throughout the white wage distribution, or the movements were
concentrated in particular segments. (23)
The shifts in the positions of new entrant and older African
Americans coincide with the changes in the wage gaps that are shown in
Table 1. The changes in position are greatest at the median and 75th
percentile, with notable changes at the 25th and 90th percentiles. For
example, from 1979 to 1985, the new entrant median African American fell
from the 34th percentile of the white residual wage distribution to the
31st percentile. During this period, the median older male's
position fell slightly, from the 38th to the 36th percentile. The
reverse occurs from 1985 to 1994. The median new entrant African
American's position improved to the 36th percentile, whereas the
median older African American's position remained virtually
unchanged. The drop in the relative status is because of the 75th and
90th percentile blacks' falling in the wage distribution.
Instead of rising in the white residual wage distribution, the
position of blacks at the upper tail of the white distribution actually
worsens. According to the logic in Seun (1997), this means that the
erosion in the position at the upper tails is an underestimate of the
change in location. For example, instead of the 90th percentile older
black falling from the 85th to the 81st percentile, the drop may have
been to a percentile below the 81st percentile. The movement of the
median black in the white residual wage distribution provides a better
representation of the roles that worsening discrimination and the
relative decline in the unobservable skills of blacks play in causing
the wage gap to expand.
Table 2 also reports the positions of African American high school
dropouts, high school graduates, and college graduates in their
respective white residual wage distributions. These, too, are consistent
with the changes in the wage gaps in Table 1. African American high
school dropouts and graduates lost ground from 1979 to 1985. The reverse
occurs after 1985, particularly for new entrant high school dropouts and
graduates. Table 2 shows the large erosion in the relative status of
African American college graduates that started after 1985. New entrant
black college graduates fell from the 52nd percentile to the 38th
percentile.
Except for older black college graduates, the movement of older
black high school dropouts and graduates in the white residual
distribution is less pronounced. The experience of these older men
partially insulates them from the economic downturns that occurred in
the early 1980s and 1990s. The figures in Table 2 provide a mixed
message. The positions of black high school dropouts and graduates are
stable from 1979 to 1985, but after 1985, the positions of the 10th
percentile and median blacks improve, whereas the positions of the 75th
and 90th percentile blacks worsen. The relative position of black
college graduates exhibits a modest decline from 1979 to 1985 and a
dramatic decline from 1985 to 1994. For example, the median black
college graduate fell from the 51st percentile to the white median and
then to the 38th percentile by 1994.
To provide the distribution-specific decompositions developed in
Equations 6-12 with a point of comparison, I construct the JMP
decompositions for 1979 to 1994, with a breakpoint in 1985. The
motivation for setting the breakpoint in 1985 instead of 1987, which JMP
uses, comes from the evidence presented in Table 2. The decline in the
relative position of non-college graduate black men typically reaches a
maximum in 1985 and the decline in the relative position of black
college graduates starts in 1985.
Table 3 reports estimates of the average annual rates of change in
each component by estimating a linear spline with 1985 as the
breakpoint. (24) Changes in unobservable prices matter, but not to the
degree as found in JMP. I attribute this difference to my use of the CPS
ORG data and not the Annual Demographic files of the CPS that JMP use in
their analysis. Additionally, the trend analysis in this paper is done
for 1979 to 1994, with a breakpoint in 1985, whereas the JMP trend
analysis is done for 1963 to 1987, with breakpoints in 1970 and 1979.
From 1979 to 1985, the new entrant actual mean wage gap expanded at
0.25% per year. (25) Changes in unobservable prices account for only 40%
of the actual gap's increase. From 1985 to 1994, the new entrant
gap continued to expand at 0.60% per year. Changes in unobservable
prices lead to the gap's increasing by 0.18% per year. For older
men, during the first half of 1980, the actual wage gap expanded at
0.14% per year; however, the estimate is not measured with precision.
From 1985 to 1994, the gap grew by 1.18% per year. The role of
unobservable prices is modest, contributing an average annual increase
of 0.18%.
Table 3 reports the mean decompositions by educational attainment.
For new entrant and older male high school dropouts, the most notable
result is a narrowing in each gap from 1985 to 1994. The new entrant gap
narrowed by 0.87% per year and the wage gap among older men narrowed at
a rate of 0.66% per year. For new entrants, although relative
improvements in observable prices and unobservable skills/discrimination
helped to lessen the overall wage gap, changes in unobservable prices
still acted to increase the gap.
The new entrant high school graduate gap expanded by 0.66% per year
from 1979 to 1985 and contracted by 0.39% per year from 1985 to 1994.
One half of the widening was because of a decline in the relative
education and experience of black men. The other half was because of
changes in residual wage inequality, with unobservable prices
contributing 0.12 percentage points to the overall gap's expansion.
After 1985, albeit in a smaller role, changes in unobservable prices
still act to expand the gap. During the first half of the 1980s, the
trend among older men is similar to that for new entrants. After 1985,
the gap continues to expand at 0.20% per year. One half of the growth is
because of changes in unobservable prices.
Table 3's most startling results are for black college
graduates. The decompositions indicate that from 1979 to 1985 the new
entrant gap expands by 0.91% per year and that changes in unobservable
prices explain very little of this change. The major contributor to the
gap's expansion is the decline in the relative position of African
American college graduates in the white college graduate residual wage
distribution: a 0.82% annual increase in the gap. This was clearly seen
in Table 2. From 1985 to 1994, the new entrant gap continued to expand
at 0.56% per year and the mean position of blacks continued to fall in
the white distribution at 1.39% per year. A relative narrowing in the
observable skills of black and white college graduates of 0.79% per year
helped to offset the drop in the white distribution.
A similar pattern occurs among older college graduates. The wage
gap expands at 1.34% per year from 1979 to 1985. A decline in the
location of African Americans in the white distribution is the primary
source of the divergence in earnings. From 1985 to 1994, the gap
continued its expansion at an average annual rate of 0.73%. During this
subperiod, unobservable prices explain very little of the actual
gap's expansion. Although estimated with modest precision, the drop
in the relative position of African American college graduates explains
82% of the mean wage gap's expansion.
The mean decompositions in Table 3 confirm the importance of
decomposing changes in the overall wage gap into the contribution due to
changes in observable skills and prices, but also decomposing the
residual wage gap into the contribution of changes in unobservable
prices and skill. However, it is not possible to determine whether the
contribution of changes in unobservable prices to the mean wage
gap's expansion is greatest at the upper segments of the skill
distribution. Further, if the mean position of blacks in the white
residual wage distribution and white wage inequality are dependent, then
the estimates in Table 3 of the "Gap" and "Unobservable
Prices" terms are biased.
The "Gap" term is biased downward and the
"Unobservable Prices" term is biased upward. Growing
inequality artificially raises the position of blacks, particularly at
the tails of the distribution. To assess whether the contribution of
changes in unobservable prices to the mean wage gap's expansion is
greatest at the upper segments of the residual wage distributions and
the extent to which the JMP decompositions are biased, Table 4 presents
statistics from my distribution-specific residual log hourly wage
technique. The decompositions are for the white-black wage gaps at the
10th, 25th, median, 75th, and 90th percentiles.
The decompositions in Table 4 suggest that the JMP decompositions
of the residual wage gap are consistent with Reardon (1997). The
increased variance explanation is most important at the middle and upper
tails of the residual wage distribution (i.e., medium- and high-skilled
workers). For new entrants, the change in the mean actual wage gap from
1979 to 1985 is 5.3%, which corresponds to a 0.76% average annual
increase from 1979 to 1985, similar to the average annual increase of
0.47% in the JMP decomposition. (26) The average predicted change is
1.7%, generating a ratio of 32-34%. This ratio is slightly higher than
the 22% contribution of changes in unobservable prices found in Table 3
of the JMP decomposition. The median decomposition indicates that
growing inequality has a greater contribution to the wage gap's
expansion, but this is because the change in the median gap is smaller
than the change in the mean gap. The similar predicted change at the
median and mean indicates that growing wage inequality played a similar
role in causing the actual wage gap to grow.
Across the distribution, the Actual Changes in the Gaps (ADGAP)
that are calculated from the sample range from 5.7% at the 10th
percentile to 6.8% at the 75th percentile, correspond to average annual
increases in the wage gap of 0.81 to 0.90%. The predicted changes are
the expected signs at every percentile except the 10th percentile.
Although the ratios indicate that growing wage inequality plays a role
among highly skilled blacks and whites, estimates of the ratio of the
predicted and actual changes in the gap, RATIO, indicate that the
predicted change has its greatest explanatory power at the median.
Again, this is largely because of the fact that the actual change in the
median wage gap is smaller than the actual change in the wage gaps at
the 25th, 75th, and 90th percentiles.
Table 4 reports the distribution-specific decompositions of changes
in older male wage gaps from 1985 to 1994. Inequality growth matters at
the tails of the distribution; however, because the ratios at the 10th
and 25th percentiles exceed 1, these estimates probably represent an
upper bound on inequality growth's contribution to the wage
gap's expansion.
The bootstrapped predicted and actual changes are virtually
identical to the sample values, and the asymptotic standard deviations
indicate that the actual and predicted changes are measured with a high
degree of precision. (27) However, in several cases, the bootstrapped
RATIOs perform poorly. Either they have little precision or outliers
generate ratios that differ from creating the RATIO from the bootstrap
mean values of the actual and predicted changes.
Table 5 reports the distribution-specific decompositions by
educational attainment and potential experience. The actual change in
the high school graduate wage gap ranges from 6.4% at the 10th
percentile to 11.2% at the 90th percentile. The predicted changes are of
the hypothesized sign at the 10th, 75th, and 90th percentiles. Because
of this, the ratio is only positive at these segments of the
distribution. The contribution of growing wage inequality is greatest at
the 90th percentile. If the increased variance explanation contributes
to the widening of the high school graduate racial wage gap then it
occurs among the least- and highest-skilled high school graduates, with
both potentially subject to the bias associated with the dependence
between wage inequality growth and the position of blacks in the white
distribution.
The estimates for new entrant college graduates are consistent with
the prediction that if wage inequality growth plays a role in the wage
gap's expansion, its contribution is among the highest-skilled
blacks and whites. Increased variance in the distribution of wages
explains a portion of the gap's change at the 75th and 90th
percentiles. It explains one-half of the gap at the 75th percentile and
overpredicts the change in the gap at the 90th percentile. A portion of
the growth in the disadvantage of highly-skilled new entrant black
college graduates can be attributed to growing wage inequality among
highly-skilled college graduates.
Shifting to decomposing the actual change in the wage gap among
older men for the 1985-1994 period reveals that growing inequality is
most important in explaining the high school graduate wage gap's
change at the 90th percentile. For older male college graduates, the
contribution of increased variance in the distribution of wages occurs
at the 10th, 25th, and 75th percentiles. In summary, disaggregating by
educational attainment and skill reveals the limited ability to globally
conclude that the increased variance explanation is the major
contributor to the racial inequality that emerged after 1985. Inequality
growth plays a role in expanding wage gaps among the least-skilled
whites and blacks and the highest-skilled blacks and whites. Given the
work of Seun (1997), we must be cautious in how much weight we put on
inequality growth's contribution among the least-skilled.
5. Conclusions
Wage decompositions are useful techniques for describing racial
wage gaps in both levels and their changes over time. (28) Focusing on
explaining changes over time, JMP add to this literature by decomposing
changes in the residual wage gap into a portion that measures the impact
that changes in the position of blacks in the white distribution have on
changes in the mean wage gap, and a portion that measures changes in the
prices of unobservable skills. They find that the increased variance in
the distribution of wages is quite important for explaining the erosion
in the relative wages of new entrant blacks during the first half of the
1980s. In fact, their results suggest that the erosion had little to do
with growing racial discrimination and/or a widening of racial
differences in unmeasured skills, and more to do with general changes in
the wage structure that put lower-skilled men, regardless of race, at a
greater disadvantage.
Using different data and years, Reardon (1997) shows that the
general inequality story is most important in explaining racial
inequality growth among high-skilled blacks and whites. Further, Seun
(1997) shows, analytically, that JMP's decomposition technique
biases upward the contribution of changes in unobservable prices, and
biases downward the role of unobservable skills. As inequality widens,
the mean position of blacks in the white distribution improves.
This study builds on this past work by developing methods that
decompose changes in the wage gap by time period, level of experience,
and educational attainment. The disaggregation and technical innovation
are important for the following reasons. Applying the JMP and
distribution-specific decompositions to the disaggregated data and
segments of the skill distribution indicates that general inequality
growth cannot be used as a general explanation for the wage gap's
expansion, overall and within categories of educational attainment. The
skill-specific decompositions are unbiased as long as there is little
statistical dependence between increasing inequality and changes in the
position of blacks in the white wage distribution. For example, as long
as there is no link between movements in the position of the median
black and increasing white wage inequality growth in the 30th-40th
percentiles of the distribution, then the median decomposition provides
a useful representation of the contribution that general inequality
growth plays in explaining the median white-black wage gap's
expansion.
Much of the work on male racial inequality focuses on describing
and explaining the new entrant wage gap because this demographic is most
sensitive to macroeconomic and structural change. However, the inclusion
of decompositions of changes in the white-black wage gap among slightly
older men provides additional insight to understanding the 1980s
expansion. The decompositions presented in this paper indicate that the
mean wage gap among older men continued to expand after 1985. Its
expansion appears to be largely driven by the movement of new entrants
who joined the labor market in the early 1980s into the potential
experience category of 11-20 years of potential experience. One
interpretation of this pattern is that the adverse labor market
conditions of the 1980s recession that this cohort of African Americans
faced placed them on lower relative lifetime earnings paths than
observationally equivalent white men.
What are these adverse conditions? No one factor can receive all of
the blame. First, a well-developed literature finds that blacks,
especially those with the least education and potential experience, bear
the brunt of recessions. (29) Second, the evidence on industry shifts
and skill-biased technological change found in Bound and Freeman (1992),
Bound and Holzer (1996), and Reardon (1997) all play a role. All of
these more general factors placed African American men, even African
American college graduates who entered the labor market in the early
1980s, at an even greater initial disadvantage than white men.
As these men accumulated labor market experience, why did the
relative value of their skills continue to deteriorate after 1985? The
selective withdrawal of the least-skilled African Americans would cause
the gap to narrow, which is not the case. Thus, I speculate that the
early disadvantages had an impact on their abilities to receive
promotions, as well as to participate in and receive similar payoffs to
job training. (30) Longitudinal data must be used to rigorously verify this conclusion.
Data Appendix
Construction of Years of Schooling
Prior to 1992, respondents were asked, "What is the highest
grade or year of regular school ... has ever attended?" and
"Did ... complete the grade?" (31) In 1992, the CPS switched
to a credential-oriented measure of attainment. With this new
information, potential experience cannot be constructed. Information in
the February 1990 CPS provides a potential solution to this problem.
During this month, respondents were asked both questions. To predict
years of schooling and potential experience for respondents in the
1992-1994 files, I use the average years of schooling in the February
1990 CPS by education level.
The mean values that come from a regression of years of schooling
on a series of dummy variables are as follows: Education = 5-6, 2.642;
Education = 7-8, 6.732; Education = 9, 8.446; Education 10, 9.389;
Education = 11, 10.369; Education = 12, 11.042; High School Graduate,
11.480; Some College, 12.937; AA Degree-Vocational, 13.599; AA
Degree-Academic, 13.861; BA Degree, 15.646; MA Degree, 17.164;
Professional Degree, 17.203; Doctoral Degree, 17.288; Constant, 0.515.
To construct potential experience, I rounded the cell means to their
closest integer. Reardon (1997) uses this cell mean approach. I also
constructed predictions based on coefficients from a regression of years
of schooling on dummy variables for education category, race, sex,
region of residence, class of work, union membership, urban residence,
industry and occupation of affiliation, and marital status. The addition
of these sociodemographic variables had no impact on the constructed
years of schooling distributions. These additional results are available
upon request from the author.
Construction of Log Hourly Wages
From 1979 to 1988, weekly wages are topcoded at $999. In 1989, the
topcode is raised to $1923. If a smaller share of black men's wages
is topcoded, then the mean gap is biased downward. To adjust for this
potential bias, researchers typically impute wages for individuals at
the $999 topcode. For example, Bound and Freeman (1992) use their sample
of new entrants at the $999 cap in 1989 to calculate the geometric mean of weekly wages. The value was $1227. They assign this value to men in
all years, instead of using this adjustment, I use an alternative
measure of central tendency: the median. The advantage of the estimating
median gaps is that they are robust to topcoding and less sensitive to
the increased variance in wages. A disadvantage of using median gaps
will be their greater sensitivity to mass points or spikes in the data.
References
Armstrong, Ronald D., Edward L. Frome, and D. S. Kung. 1979.
Algorithm 79-01: A revised simplex algorithm for the absolute deviation curve fitting problem. In Communications in statistics, simulation, and
computation B8(2). New York: Marcel Dekker, pp. 175-90.
Blank, Rebecca M. 1989. Disaggregating the effect of the business
cycle on the distribution of income. Economica 56:141-63.
Bound, John, and Richard B. Freeman. 1989. Black economic progress:
Erosion of the past 1965 gains in the 1980s. In The question of
discrimination: Racial inequality in the U.S. labor market, edited by
William Darity and Steven Shulman. Middletown, CT: Wesleyan University
Press, pp. 32-49.
Bound, John, and Richard B. Freeman. 1992. What went wrong? The
erosion of relative earnings and employment among young black men in the
1980's. The Quarterly Journal of Economics 107:201-32.
Bound, John, and Harry J. Holzer. 1996. Demand shifts, population
adjustments, and labor market outcomes during the 1980s. NBER Working
Paper No. 5685.
Buchinsky, Moshe. 1991. Changes in the structure of wages in the
U.S. 1963-87: Application of quantile and censored quantile regressions.
Econometrica 62:405-58.
Buchinsky, Moshe. 1998. Recent advances in quantile regression
models: A practical guide for empirical research. The Journal of Human
Resources 33:88-126.
Butler, Richard, and James J. Heckman. 1977. The government's
impact on the labor market status of black Americans: A critical review.
In Equal rights and industrial relations, edited by Leonard J. Hausman and Farrell E. Bloch. (June 1977). NBER Working Paper No. 183.
Chamberlain, Gary. 1991. Quantile regression, censoring and the
structure of wages. Harvard Institute of Economic Research Discussion
Paper No. 15558.
Chandra, Amitabh. 2000. Labor market dropouts and the racial wage
gap. American Economic Review 90:333-8.
Chandra, Amitabh. 2003. Is the convergence in the racial wage gap
illusory? NBER Working Paper No. 9476.
Corcoran, Mary, and Greg J. Duncan. 1979. Work history, labor force
attachment, and earnings differences between the races and sexes. The
Journal of Human Resources 14:1-20.
Cotton, Jeremiah. 1988. On the decomposition of wage differentials.
The Review of Economics and Statistics 70:236-324.
Duncan, Greg J., and Saul Hoffman. 1979. On-the-job training and
earnings differences by race and sex. Review of Economics and Statistics
61:594-603.
Duncan, Kevin C. 1992. The vintage schooling hypothesis and racial
differences in earnings mid on-the-job training: A longitudinal
analysis. The Review of Black Political Economy, 20:99-117.
Flanagan, Robert J. 1973. Labor force experience, job turnover, and
racial wage differentials. The Review of Economics and Statistics
55:521-9.
Hoffman, Saul, and Charles R. Link. 1984. Selectivity bias in male
wage equations: Black-white comparisons. The Review of Economics and
Statistics 66:320-4.
Juhn, Chinhui. 2003. Labor market dropouts and trends in the wages
of black and white men. Industrial and Labor Relations Review 56:643-62.
Juhn, Chinhui, Kevin M. Murphy, and Brooks Pierce. 1991. Accounting
for the slowdown in black-white convergence. In Workers and their wages:
Changing patterns in the U.S., edited by Marvin Kosters. Washington, DC:
The AEI Press, pp. 107-43.
Koenker, Roger W., and Gilbert W. Bassett. 1978. Regression
quantiles. Econometrica 46:33-50.
Koenker, Roger W., and Gilbert W. Bassett. 1982. Robust test for
heteroscedasticity based on regression quantiles. Econometrica 50:43-61.
Kominski, Robert, and Paul M. Siegel. 1993. Research summaries:
Measuring education in the current population survey. Monthly Labor
Review (September) 116(9):34-8.
Neal, Derek A., and William R. Johnson. 1996. The role of premarket
factors in black-white wage differences. Journal of Political Economy
104:869-95.
Oaxaca, Ronald L., and Michael R. Ransom. 1994. On the
discrimination and the decomposition of wage differential. Journal of
Econometrics 61:5-21.
Polivka, Anne. 1996. Data watch: The redesigned current population
survey. Journal of Economic Perspectives 10(3):169-80.
Powell, James. 1984. Least absolute deviations estimation lot the
censored regression model. Journal of Econometrics 25:303-25.
Powell, James. 1986. Censored regression quantiles. Journal of
Econometrics 32:143-55.
Reardon, Elaine. 1997. Demand-side changes and the relative
economic progress of black men: 1940-90. Journal of Human Resources
32:69-97.
Reich, Michael. 1981. Racial inequality: A political-economic
analysis. Princeton, NJ: Princeton University Press.
Reimers, Cordelia. 1983. Labor market discrimination against
Hispanic mid black men. The Review of Economics and Statistics 65:570-9.
Rodgers, William M., III. 1997a. Male sub-metropolitan black-white
wage gaps: New evidence for the 1980s. Urban Studies 34:1201-13.
Rodgers, William M., III. 1997b. Measuring wage discrimination
during periods of growing overall wage inequality. In Race, markets and
social outcomes, edited by Patrick L. Mason and Rhonda M. Williams.
Boston, MA: Kluwer Academic Publishers, pp. 67-90.
Rodgers, William M., III, and Richard B. Freeman. 2005. The
fragility of the 1990s gains. Washington, DC: Center for American
Progress.
Seun, Wing. 1997. Decomposing wage residuals: Unmeasured skill or
statistical artifact? Journal of Labor Economics 15: 555-66.
Sexton, Edwin A., and Reed N. Olsen. 1994. The returns to
on-the-job training: Are they the same for blacks and whites? Southern
Economic Journal 61:328-42.
Smith, James, and Finis Welch. 1989. Black economic progress after
Myrdal. Journal of Economic Literature 27:519-64.
Zveglich, Joseph E. Jr., Yana van der Meulen Rodgers, and William
M. Rodgers, III. 1997. The persistence of gender earnings inequality in
Taiwan, 1978 1992. Industrial and Labor Relations Review 50:594-609.
(1) See, for example, Bound and Freeman (1992) and Rodgers (1997a,
b).
(2) Convergence in racial differences in observable characteristics
and relative improvements in the mean position of blacks in the white
residual distribution swamped the influence of unobservable prices.
(3) Buchinsky (1991) and Chamberlain (1991) utilize quantile
regression techniques to examine the union relative wage effect, and how
the returns to schooling have changed since 1964. The Chamberlain and
Buchinsky studies provide a more detailed description of the conditional
distribution of wages than standard mean regression, because the wage
effect and returns are allowed to vary across the wage distribution.
(4) JMP do not estimate quantile regression models, but for a given
percentile, calculate the difference in real wage growth between high
school and college graduates who have 1 to i0 years of potential
experience (figure 4-4, p. 116). A quantile regression of the logarithm of real wage growth on a constant and an educational dummy (coded 1 if
the individual is a college graduate and 0 if the individual is a high
school graduate) yields their difference.
(5) Values for [[beta].sub.q] and [[gamma].sub.q] are obtained from
the following minimization problem:
(A1) [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.]
where [h.sub.i] = q if ([y.sub.i] - [X'.sub.i][beta] -
[R.sub.i][gamma]) > 0, and [h.sub.i] (1 - q) if ([y.sub.i] -
[X'.sub.i][beta] - [R.sub.i][gamma]) < 0. Equation A1 is
minimized with STATA, Version 5.0, which uses linear program techniques
developed in Armstrong, Frome, and Kung (1979). Homoscedastic standard
errors are estimated as suggested in Koenker and Bassett (1982).
(6) The divisions are New England, Mid-Atlantic, East North
Central, West North Central, South Atlantic, East South Central, West
South Central, and Pacific. The Mountain divisional identifier is
excluded.
(7) Note that I exclude individuals with some college from the
analysis.
(8) The exposition borrows heavily from Rodgers (1997a) and
Zveglich, Rodgers, and Rodgers (1997).
(9) See JMP for a detailed description of how these components are
constructed.
(10) Rodgers (1997b) conducts the procedure for each quartile of
the wage distribution. For example, at the lowest quartile (5th 25th
percentiles), I locate the positions of the 5th and 25th percentile
African Americans in the year t white residual wage distribution and
then find year t' white residuals that correspond to these
percentiles. The mean of these residuals is the year t' average
predicted wage for African Americans at the lowest quintile, assuming
that their year t positions in the wage distribution are preserved. I
then compute the year t and year t' averages of the white 5th-25th
percentile residual wages. The ratio is the difference between the
predicted year t' mean gap and the actual year t mean gap divided
by the change in the actual year t' and year t mean black-white
wage gaps.
(11) To assess the estimates' level of precision, I calculated
the asymptotic standard deviations. I also constructed the implied
standard deviations based on 95, 90, and 80% confidence intervals using
the percentile method. For example, to construct a 95% confidence
interval based on a bootstrap sample of 500, I found the 13th smallest
and 488th largest values in the sample. The values of 13 and 488 come
from multiplying 500 by 0.025 and 0.975. To compute the standard
deviation, I took the difference between these two values and divided by
2.564, which is 2 x 1.645, the critical value for a 95% level of
significance. I define precision as the relative size of the bootstrap
sample mean to its standard deviation.
(12) For example, the procedure at the median starts with the
estimation of separate year t median black and white regressions. I
construct the predicted black and white median wages for a reference set
of characteristics ([X.sup.*]). I, then, perform a search over the white
quantile regressions to find the [q.sup.*]th quantile, in which the
white predicted wage equals the predicted black median wage. This
[q.sup.*] denotes the location of the median black in the year t white
distribution. Using year t' data, I estimate the white quantile
regression at quantile [q.sup.*]. These coefficients, along with
[X.sup.*], are used to construct the predicted year t' [q.sup.*]th
quantile white wage. which I interpret as the predicted year t'
black median wage conditional on characteristics equal to [X.sup.*]. The
predicted year t' gap equals the difference between the conditional
white median wage and the predicted black wage (conditional [q.sup.*]th
quantile of the white wage distribution). The actual gap equals the
difference between the conditional white and black median wages. I use
these gaps to calculate the ratio of the predicted and actual changes.
To allow for a statistical interpretation of the changes in the actual
and predicted gaps, and the ratio, I performed the procedure 100 times.
The smaller sample size reflects the greater computational costs of the
quantile regression procedure.
(13) I constructed the composite distribution by pooling all of the
years from 1979 to 1985. Results from these models are available from
the author upon request.
(14) Potential Experience = Min(Age - 18, Age - Education - 6).
(15) Prior to 1994, the variable is "major activity last
week." In 1994, the CPS switched to the "mlr" variable to
determine an individual's labor force status. The Unicon Research
Corporation files that we use contain a variable that is comparable
across time.
(16) Polivka (1996) focuses exclusively on describing the redesign of the questionnaire and its impact; however, in footnote 3, Polivka
(1996) mentions that the switch to the 1990 decennial census occurred at
approximately the same time that the new questionnaire began to be used.
(17) An individual's hourly wage corresponds to his usual
earnings. For workers who are paid an hourly rate, their wage equals
their usual hourly wage. For workers paid a weekly rate, their hourly
wage equals the ratio of their usual weekly wage and usual hours worked.
(18) JMP's samples consist of black and white males who meet
the following criteria: (i) less than 10 years of potential experience,
(ii) worked at least one week during the calendar year. (iii) usually
full-time, and (iv) participated in the labor force for at least
thirty-nine weeks.
(19) For new entrants, full-time white men worked on average 1.9
hours more per week in 1979, 2.1 hours more in 1989, and 2.6 hours more
in 1994.
(20) Descriptive statistics for all other years are available from
the author upon request.
(21) From 1985 to 1989, the U.S. unemployment rate fell from 7.2 to
5.3%. White unemployment rates fell from 6.2 to 4.5%, and black
unemployment rates fell from 13.7 to 10%.
(22) The complete series are available from the author upon
request.
(23) Another interpretation of the results is as follows. A growing
body of literature finds that the greater selective withdrawal of
African Americans from the labor force as developed in Butler and
Heckman (1977) could explain the expansion in the gap. Neal and Johnson
(i996), Chandra (2000, 2003) and Juhn (2003) find evidence to the
contrary of Hoffman and Link (1984) and Smith and Welch (1989).
(24) In the interest of space, I report only the relevant findings.
As a robustness check and to allow for a direct comparison with
JMP's results for the 1979-1987 subperiod, I set the breakpoint at
1987. The results are quite similar. Detailed tables are available from
the author upon request.
(25) From 1979 to 1987, the gap expanded at 0.75% per year, and
unobservable prices account for 5.5% of the actual gap's increase.
(26) These calculations are not exactly equal to the total change
shown in Table 3 because they are computed using the endpoints (e.g.,
1979 and 1985), whereas the total changes in Table 3 also use
intervening years.
(27) The precision (e.g., the size of the bootstrap mean relative
to its standard deviation) improves when we switch to the implied
standard deviations based on confidence intervals from the percentile
method. These standard errors are available from the author upon
request.
(28) See, for example, Flanagan (1973), Corcoran and Duncan (1979),
Hoffman and Link (1984), Cotton (i988), Smith and Welch (1989), and
Oaxaca and Ransom (1994).
(29) See, for example, Reich (1981), Blank (1989). Bound and
Freeman (1989), and Rodgers and Freeman (2005).
(30) Studies by Duncan and Hoffman (1979), Duncan (1992), and
Sexton and Olsen (1994) that use data prior to 1985 find that racial
differences in training lead to a divergence in the age-earnings
profiles of black and white workers. Future research should focus on
updating this literature.
(31) Kominski and Siegel (1993) provide an excellent discussion of
the pros and cons associated with changing the educational attainment
question.
William M. Rodgers III, Rutgers, The State University of New
Jersey, John J. Heldrich Center for Workforce Development, Bloustein
School of Planning and Public Policy, 33 Livingston Avenue, 5th Floor,
New Brunswick, NJ 08901, USA and the National Poverty Center, University
of Michigan, Gerald R. Ford School of Public Policy; E-mail
wrodgers@rci. rutgers.edu.
I am indebted to two anonymous referees, Berhanu Abegaz, John
Bound, Gary Chamberlain, Richard Freeman, Jinyong Hahn, Harry Holzer,
Lawrence Katz, Patrick Mason, Michael McCarthy, Elaine Reardon, Yana
Rodgers, William Spriggs, and Joseph Zveglich for their helpful comments
and suggestions. I also thank Jared Bernstein for sharing his copy of
the February 1990 CPS file, and thank seminar participants of the
Harvard Econometrics and Labor Lunches, Amherst College, Wesleyan
College, Stanford University Graduate School of Business, University of
California at Berkeley, Georgia State University, The College of William
and Mary, University of Michigan, Abt Associates, Mathematica Policy
Research, University of Maryland, John F. Kennedy School of Government,
and Vanderbilt University for helpful comments, and the Harvard
University Graduate School of Arts and Sciences, the National Bureau of
Economic Research, the W.E.B. DuBois Institute for Afro-American
Research, and the National Science Foundation for funding. This paper
draws heavily from my Ph.D. dissertation, "Employment and Earnings
of Young Males: 1979 1991." Alison Pastemak provided excellent
research assistance.
Received April 2001; accepted August 2005.
Table 1. Estimated Log Hourly Black-White Wage Gaps,
1979-1994, by Potential Experience and Educational Attainment
High School
All Dropout
Year Mean Median Mean Median
New entrants
1979 0.102 0.124 0.127 0.176
1980 0.130 0.163 0.158 0.173
1981 0.119 0.136 0.136 0.156
1982 0.122 0.137 0.146 0.139
1983 0.106 0.134 0.123 0.123
1984 0.115 0.140 0.147 0.198
1985 0.157 0.178 0.180 0.213
1986 0.132 0.159 0.159 0.174
1987 0.138 0.169 0.153 0.143
1988 0.120 0.145 0.166 0.178
1989 0.151 0.169 0.144 0.155
1990 0.124 0.128 0.112 0.164
1991 0.125 0.139 0.079 0.079
1992 0.112 0.125 0.087 0.120
1993 0.118 0.138 0.155 0.177
1994 0.127 0.141 0.131 0.100
Older men
1979 0.158 0.171 0.179 0.186
1980 0.139 0.160 0.191 0.230
1981 0.142 0.153 0.133 0.162
1982 0.147 0.173 0.172 0.191
1983 0.139 0.159 0.197 0.233
1984 0.126 0.143 0.186 0.227
1985 0.166 0.192 0.198 0.204
1986 0.137 0.140 0.156 0.177
1987 0.162 0.195 0.141 0.185
1988 0.153 0.181 0.155 0.189
1989 0.185 0.192 0.192 0.230
1990 0.193 0.197 0.154 0.201
1991 0.192 0.195 0.187 0.199
1992 0.206 0.226 0.196 0.205
1993 0.223 0.237 0.123 0.135
1994 0.194 0.212 0.140 0.144
High School College
Graduates Graduates
Year Mean Median Mean Median
New entrants
1979 0.122 0.144 0.041 -0.019
1980 0.150 0.182 0.009 0.054
1981 0.153 0.160 0.001 -0.015
1982 0.137 0.157 0.026 0.000
1983 0.116 0.135 0.029 0.075
1984 0.134 0.144 0.076 0.143
1985 0.176 0.202 0.072 -0.009
1986 0.156 0.187 0.101 0.174
1987 0.154 0.182 0.109 0.111
1988 0.117 0.141 0.079 0.042
1989 0.148 0.167 0.169 0.216
1990 0.140 0.137 0.138 0.140
1991 0.139 0.182 0.168 0.151
1992 0.138 0.161 0.106 0.091
1993 0.141 0.152 0.079 0.115
1994 0.119 0.143 0.159 0.167
Older men
1979 0.158 0.146 0.106 0.115
1980 0.132 0.134 0.145 0.097
1981 0.149 0.166 0.255 0.236
1982 0.164 0.207 0.131 0.079
1983 0.156 0.182 0.083 0.053
1984 0.129 0.151 0.116 0.084
1985 0.167 0.196 0.103 0.086
1986 0.163 0.157 0.042 0.049
1987 0.189 0.220 0.180 0.193
1988 0.181 0.198 0.094 0.122
1989 0.183 0.202 0.185 0.178
1990 0.181 0.197 0.230 0.223
1991 0.192 0.205 0.250 0.229
1992 0.186 0.220 0.258 0.269
1993 0.221 0.262 0.281 0.277
1994 0.180 0.223 0.232 0.213
Author's calculations from the Outgoing Rotation Groups of the
Current Population Survey files, 1979-1994. New entrants
have no more than 10 years of potential experience; older men,
11 to 20 years of potential experience. For new entrants,
the standard errors for the mean coefficients range from 0.009 to
0.012 (all), 0.019 to 0.051 (high school dropouts), 0.013 to
0.017 (high school graduates), and 0.026 to 0.046 (college graduates),
and the standard errors for the median coefficients range
from 0.008 to 0.014 (all), 0.021 to 0.045 (high school dropouts), 0.001
to 0.017 (high school graduates), and 0.029 to 0.068 (college
graduates). For older men, the standard errors for the mean
coefficients range from 0.010 to 0.013 (all), 0.022 to 0.036 (high
school dropouts), 0.014 to 0.019 (high school graduates), and 0.024 to
0.080 (college graduates), and the standard errors for the median
coefficients range from 0.010 to 0.017 (all), 0.026 to 0.047
(high school dropouts), 0.010 to 0.025 (high school graduates),
and 0.025 to 0.137 (college graduates).
Table 2. Location of Black Men in White Residual Wage Distribution
New Entrants
(Potential Experience 1-10 Years)
Year 10 25 50 75 90
All men
1979 7 15 34 64 85
(0.48) (0.70) (1.38) (1.37) (0.99)
1985 5 13 31 58 81
(0.37) (0.64) (1.30) (1.55) (1.59)
1987 5 15 33 61 81
(0.49) (0.78) (1.26) (1.61) (1.19)
1994 9 19 36 59 78
(0.77) (0.93) (1.27) (1.42) (1.16)
High school dropouts
1979 7 13 26 59 83
(0.96) (1.28) (2.48) (3.50) (2.74)
1985 6 12 25 45 72
(1.11) (1.60) (2.86) (3.75) (7.91)
1987 5 14 30 54 78
(1.03) (2.04) (2.86) (3.67) (6.06)
1994 17 26 40 53 65
(4.70) (3.78) (3.94) (3.83) (4.15)
High school graduates
1979 6 13 32 62 84
(0.49) (1.06) (1.56) (2.22) (1.32)
1985 5 12 29 56 78
(0.49) (0.87) (1.68) (1.82) (2.14)
1987 5 14 31 57 78
(0.59) (0.94) (1.74) (2.17) (2.01)
1994 10 18 34 57 79
(0.95) (1.26) (1.82) (1.98) (2.55)
College graduates
1979 8 22 51 72 86
(3.15) (4.53) (6.60) (4.08) (4.79)
1985 4 19 52 71 86
(1.44) (7.14) (5.06) (3.95) (3.66)
1987 5 16 40 68 87
(1.88) (3.35) (5.66) (4.61) (3.08)
1994 4 15 38 64 80
(1.16) (2.10) (2.70) (2.63) (2.49)
Old Men
(Potential Experience 11-20 Years)
Year 10 25 50 75 90
All men
1979 6 14 38 68 84
(0.30) (0.70) (1.05) (0.81) (0.68)
1985 6 15 36 66 83
(0.24) (0.47) (0.97) (0.97) (0.53)
1987 6 15 37 67 85
(0.36) (0.68) (1.16) (0.79) (0.55)
1994 7 16 37 63 81
(0.33) (0.51) (0.86) (0.84) (0.71)
High school dropouts
1979 7 13 35 65 85
(0.49) (0.94) (2.01) (1.84) (1.24)
1985 7 14 33 63 86
(0.53) (1.06) (1.84) (2.24) (1.60)
1987 7 17 37 67 88
(0.73) (1.49) (2.06) (2.33) (1.44)
1994 11 19 38 64 84
(1.37) (1.73) (2.12) (3.08) (2.34)
High school graduates
1979 5 13 37 66 83
(0.30) (0.86) (1.58) (1.49) (1.24)
1985 5 14 34 63 83
(0.28) (0.79) (1.31) (1.22) (0.78)
1987 5 13 34 65 84
(0.31) (0.91) (1.01) (1.36) (0.98)
1994 8 15 34 62 82
(0.34) (0.65) (0.91) (1.54) (1.11)
College graduates
1979 9 22 51 73 84
(2.19) (4.52) (4.94) (2.70) (3.01)
1985 8 19 49 69 82
(1.53) (3.91) (3.35) (2.61) (2.32)
1987 5 15 41 67 83
(1.06) (2.35) (3.36) (2.93) (2.61)
1994 5 14 38 60 78
(0.63) (1.16) (1.57) (1.61) (1.49)
Author's tabulations from the Current Population Survey
Outgoing Rotation Group files. Entries represent the
bootstrapped location of black men in the white residual
log hourly wage distribution. The residual distributions
are constructed using education and potential experience
coefficients from the white regression line. Separate
regressions are estimated for each potential experience
group. The bootstrap statistics are based on 500 random
samples of the population. All bootstrap entries are the
sample mean of the given statistic. The asymptotic standard
deviations are reported in parentheses.
Table 3. White-Black Log Hourly Wage Gap Decompositions, 1979-1994
All
1979-1994 1979-1985 1985-1994
Young men
Total 0.477 0.2532 0.603
(0.1136) (0.3313) (0.2096)
Observable 0.3214 -0.2177 0.6251
quantities (0.0820) (0.1843) (0.1166)
Observable 0.114 0.0052 0.1753
prices (0.0234) (0.0616) (0.0390)
Gap -0.1122 0.3645 -0.3806
(0.0816) (0.1974) (0.1249)
Unobservable 0.1537 0.1012 0.1833
prices (0.0174) (0.0493) (0.0312)
Older men
Total 0.8046 0.1413 1.1782
(0.1560) (0.4204) (0.2660)
Observable 0.1621 -0.1917 0.3613
quantities (0.0567) (0.1321) (0.0836)
Observable 0.1755 0.1939 0.1652
prices (0.0247) (0.0733) (0.0464)
Gap 0.2906 -0.0364 0.4748
(0.0880) (0.2432) (0.1539)
Unobservable 0.1764 0.1755 0.1769
prices (0.0162) (0.0482) (0.0305)
High School Dropouts
1979-1994 1979-1985 1985-1994
Young men
Total -0.3932 0.4615 -0.8746
(0.1691) (0.4344) (0.2749)
Observable 0.0591 0.2066 -0.024
quantities (0.0625) (0.1806) (0.1143)
Observable -0.2509 -0.1481 -0.3087
prices (0.0405) (0.1166) (0.0738)
Gap -0.2677 0.5048 -0.7028
(0.1570) (0.4071) (0.2576)
Unobservable 0.0663 -0.1017 0.1609
prices (0.0500) (0.1402) (0.0887)
Older men
Total -0.4364 -0.039 -0.6602
(0.1121) (0.3120) (0.1974)
Observable -0.1278 -0.0436 -0.1752
quantities (0.0245) (0.0684) (0.0433)
Observable -0.2899 0.0764 -0.4963
prices (0.0496) (0.0999) (0.0632)
Gap -0.0698 -0.1957 0.0011
(0.1154) (0.3410) (0.2158)
Unobservable 0.0511 0.1239 0.0101
prices (0.0185) (0.0508) (0.0321)
High school Graduates
1979-1994 1979-1985 1985-1994
Young men
Total -0.0119 0.6566 -0.3884
(0.1088) (0.2557) (0.1618)
Observable 0.1318 0.3478 0.0101
quantities (0.0360) (0.0860) (0.0544)
Observable -0.0808 -0.0516 -0.0973
prices (0.0246) (0.0727) (0.0460)
Gap -0.1427 0.2367 -0.3564
(0.0924) (0.2507) (0.1587)
Unobservable 0.0799 0.1237 0.0552
prices (0.0142) (0.0403) (0.0255)
Older men
Total 0.3159 0.5206 0.2006
(0.0756) (0.2164) (0.1370)
Observable 0.071 0.064 0.075
quantities (0.0087) (0.0258) (0.0163)
Observable -0.0621 0.1277 -0.169
prices (0.0235) (0.0416) (0.0264)
Gap 0.1565 0.0951 0.1911
(0.0770) (0.2281) (0.1443)
Unobservable 0.1505 0.2338 0.1035
prices (0.0175) (0.0459) (0.0290)
College Graduates
1979-1994 1979-1985 1985-1994
Young men
Total 1.099 0.9061 0.5637
(0.4132) (0.2223) (0.6531)
Observable 0.5925 0.0949 -0.7887
quantities (0.1719) (0.1268) (0.2716)
Observable -0.1495 -0.1161 -0.0569
prices (0.1033) (0.0552) (0.1633)
Gap 0.5009 0.8194 1.3851
(0.3134) (0.1758) (0.4953)
Unobservable 0.155 0.1079 0.0242
prices (0.0329) (0.0194) (0.0520)
Older men
Total 1.6889 1.344 0.7315
(0.3682) (0.2050) (0.5818)
Observable 0.0448 0.0344 0.0159
quantities (0.0624) (0.0332) (0.0986)
Observable -0.0193 0.0143 0.0739
prices (0.0491) (0.0268) (0.0776)
Gap 1.4963 1.1724 0.5972
(0.3128) (0.1758) (0.4943)
Unobservable 0.1672 0.123 0.0444
prices (0.0234) (0.0147) (0.0369)
See text for detailed description.
Table 4. Residual Log Wage Procedure for Changes in Gaps by Potential
Experience Category
New Entrants from 1979 to 1985
Variable Sample Bootstrap
PDGA[P.sub.AVG] 0.0169 0.0164 (0.0031)
ADGA[P.sub.AVG] 0.0534 0.0530 (0.0139)
RATI[O.sub.AVG] 0.3166 0.3437 (0.1750)
PDGA[P.sub.10] -0.0113 -0.0113 (0.0049)
ADGA[P.sub.10] 0.0569 0.0569 (0.0185)
RATI[O.sub.10] -0.199 -0.1990 (0.1545)
PDGA[P.sub.25] 0.0117 0.0109 (0.0044)
ADGA[P.sub.25] 0.0517 0.0536 (0.0152)
RATI[O.sub.25] 0.2271 0.2215 (0.1186)
PDGA[P.sub.50] 0.0202 0.0208 (0.0041)
ADGA[P.sub.50] 0.0376 0.0394 (0.0190)
RATI[O.sub.50] 0.5370 0.4542 (8.3946)
PDGA[P.sub.75] 0.0077 0.0067 (0.0040)
ADGA[P.sub.75] 0.0631 0.0675 (0.0197)
RATI[O.sub.75] 0.1216 0.1079 (0.0984)
PDGA[P.sub.90] 0.0129 0.0103 (0.0050)
ADGA[P.sub.90] 0.0586 0.0584 (0.0265)
RATI[O.sub.90] 0.2204 -0.4521 (11.9617)
Older men from 1985 to 1994
Variable Sample Bootstrap
PDGA[P.sub.AVG] 0.0010 0.0007 (0.0023)
ADGA[P.sub.AVG] 0.0146 0.0154 (0.0103)
RATI[O.sub.AVG] 0.0672 0.0745 (2.1426)
PDGA[P.sub.10] -0.0134 0.0283 (0.0051)
ADGA[P.sub.10] 0.0573 0.0103 (0.0144)
RATI[O.sub.10] -0.2249 2.7442 (16.2600)
PDGA[P.sub.25] 0.0445 0.0420 (0.0040)
ADGA[P.sub.25] 0.0362 0.0339 (0.0137)
RATI[O.sub.25] 1.2295 1.3364 (6.9200)
PDGA[P.sub.50] -0.0028 -0.0025 (0.0038)
ADGA[P.sub.50] 0.0006 0.0028 (0.0166)
RATI[O.sub.50] -4.4837 -0.1457 (1.6662)
PDGA[P.sub.75] -0.0185 -0.0178 (0.0032)
ADGA[P.sub.75] 0.0226 0.0206 (0.0159)
RATI[O.sub.75] -0.8180 -0.7905 (8.2098)
PDGA[P.sub.90] 0.0134 0.0151 (0.0035)
ADGA[P.sub.90] 0.0421 0.0390 (0.0157)
RATI[O.sub.90] 0.3182 0.1730 (6.0366)
Author's calculations from the CPS ORG files. The bootstrap statistics
are based on 500 random samples of the population. PDGAP denotes the
predicted change in the white-black wage gap given that the black
position in the white wage distribution does not change. ADGAP denotes
the actual change in the gap. RATIO measures the increase in the
variance of wage's contribution to the gap's actual change. The
subscripts denote percentiles. All bootstrap entries are the sample
means of the given statistics.
Table 5. High School and College Graduate Decompositions (Quantile
Regression Procedures) for 1979-1985 and 1985-1994
High School Graduates
Sample Bootstrap
New entrants 1979-1985
PDGA[P.sub.10] 0.0253 0.0283 (0.0167)
ADGA[P.sub.10] 0.0679 0.0685 (0.0213)
RATI[O.sub.10] 0.3730 0.4809 (0.4366)
PDGA[P.sub.25] 0.0290 0.0324 (0.0148)
ADGA[P.sub.25] 0.0896 0.0819 (0.0185)
RATI[O.sub.25] 0.3235 0.4428 (0.2792)
PDGA[P.sub.50] 0.0129 0.0144 (0.0113)
ADGA[P.sub.50] 0.1013 0.0885 (0.0276)
RATI[O.sub.50] 0.1274 0.1895 (0.2772)
PDGA[P.sub.75] -0.0012 0.0106 (0.0164)
ADGA[P.sub.75] 0.0972 0.0923 (0.0316)
RATI[O.sub.75] -0.0125 0.1388 (0.2982)
PDGA[P.sub.90] 0.0370 0.0296 (0.0160)
ADGA[P.sub.90] 0.0726 0.0689 (0.0362)
RATI[O.sub.90] 0.5091 0.5155 (0.4396)
Older men from 1985 to 1994
PDGA[P.sub.10] -0.0206 -0.0316 (0.0260)
ADGA[P.sub.10] -0.0385 -0.0301 (0.0421)
RATI[O.sub.10] 0.5342 -1.0037 (7.1077)
PDGA[P.sub.25] -0.0358 -0.0422 (0.0164)
ADGA[P.sub.25] -0.0214 -0.0218 (0.0295)
RATI[O.sub.25] 1.6737 2.6184 (12.1091)
PDGA[P.sub.50] -0.0125 -0.0109 (0.0171)
ADGA[P.sub.50] -0.0288 -0.0169 (0.0276)
RATI[O.sub.50] 0.4327 0.2621 (8.6648)
PDGA[P.sub.75] 0.0063 0.0235 (0.0148)
ADGA[P.sub.75] -0.0032 -0.0035 (0.0265)
RATI[O.sub.75] -1.9711 0.5995 (8.9206)
PDGA[P.sub.90] 0.0268 0.0276 (0.0153)
ADGA[P.sub.90] 0.0237 0.0138 (0.0388)
RATI[O.sub.90] 1.1335 -2.4691 (30.9925)
College Graduates
Sample Bootstrap
New entrants 1979-1985
PDGA[P.sub.10] -0.0046 -0.0012 (0.0263)
ADGA[P.sub.10] 0.0902 0.0592 (0.0692)
RATI[O.sub.10] -0.0512 0.1219 (1.2773)
PDGA[P.sub.25] 0.0101 0.0188 (0.0280)
ADGA[P.sub.25] 0.0782 0.0612 (0.1007)
RATI[O.sub.25] 0.1285 -0.1038 (2.1769)
PDGA[P.sub.50] -0.0126 -0.0054 (0.0172)
ADGA[P.sub.50] 0.0080 0.0019 (0.0696)
RATI[O.sub.50] -1.5814 2.1277 (20.3625)
PDGA[P.sub.75] 0.0342 0.0318 (0.0240)
ADGA[P.sub.75] 0.0604 0.0482 (0.0472)
RATI[O.sub.75] 0.5662 -0.5903 (13.5716)
PDGA[P.sub.90] 0.0300 0.0213 (0.0230)
ADGA[P.sub.90] 0.0179 0.0307 (0.0757)
RATI[O.sub.90] 1.6809 -0.2200 (3.2912)
Older men from 1985 to 1994
PDGA[P.sub.10] 0.0206 0.0142 (0.0321)
ADGA[P.sub.10] 0.0570 0.0905 (0.0481)
RATI[O.sub.10] 0.3614 0.2184 (0.5426)
PDGA[P.sub.25] 0.0134 0.0138 (0.0130)
ADGA[P.sub.25] 0.1266 0.1503 (0.0739)
RATI[O.sub.25] 0.1058 0.0912 (0.9785)
PDGA[P.sub.50] -0.0098 -0.0038 (0.0139)
ADGA[P.sub.50] 0.1761 0.1719 (0.0545)
RATI[O.sub.50] -0.0558 -0.0268 (0.1161)
PDGA[P.sub.75] 0.0270 0.0343 (0.0233)
ADGA[P.sub.75] 0.1787 0.1686 (0.0427)
RATI[O.sub.75] 0.1511 0.2369 (0.1941)
PDGA[P.sub.90] -0.0065 -0.0022 (0.0238)
ADGA[P.sub.90] 0.1273 0.1126 (0.0564)
RATI[O.sub.90] -0.0508 0.0508 (0.7731)
Author's calculations from the CPS ORG files. The bootstrap statistics
are based on 100 replications of the procedure. Random samples of the
population are created in each bootstrap sample. PDGAP denotes the
predicted change in the white-black wage gap given that the black
position in the white wage distribution does not change. ADGAP denotes
the actual change in the gap. RATIO measures the increase in the
variance of wage's contribution to the gap's actual change. The
subscripts denote percentiles.