Journal of Economic and Social Measurement 22 (1996) 43-55 IOS Press 43 Discrimination due to race and gender in the youth labor market: is it a double jeopardy? Deanna L. Sharpe* Consumer and Family Economics Department, College of Human Environmental Sciences, University of Missouri, USA Mohatned Abdel-Ghany Department of Consumer Sciences, College of Human Environmental Sciences, The University of Alabama, USA A wage decomposition method is used to examine components of average wage differentials in the youth labor market, letting both race and gender vary. Issues of selection bias and computation of the nondiscriminatory wage are addressed. Findings indicate that bias in the youth labor market focuses more on gender than race. However, until researchers devise consistent methods of estimating the source, amount, and direction of discrimination, policy makers face difficulty devising procedures to correct discriminatory wage differences. 1. Introduction Racial and gender bias in wages has long interested labor economists (see, for example, [5, 7, 8, 10, 14, 16, 18, 22, 23]). Explanations for differing average wages among whites and blacks, males and females have focused on both sides of the labor market. According to the human capital approach, increased education and training improves the quality of labor supply, resulting in higher wages. Thus, attempts to equalize the quality of human capital endowments such as education, on-the-job training, etc., should result in a narrowing of wage differentials among different groups of individuals. Wage differentials which persist among those with equal education and training suggests a differential demand exists in the labor market for certain racial or gender groups, pointing to a need for public policy initiatives to decrease the incidence of overt racial or gender discrimination. Wage decomposition methods offer a means of examining the sources of wage differentials and identifying the impact of both human capital endowments and discrimination on average wages earned by different racial and gender groups. Most previous studies of wage decomposition, however, have either focused on 'Correspondence to: Deanna L. Sharpe, Consumer and Family Economics Department, College of Human Environmental Sciences, University of Missouri, Columbia, MO 65211, USA. E-mail; cfedls@mizzou I .missouri.edu. 0747-9662/96/$8.00 © 1996 - IOS Press. All rights reserved 44 D.L. Sharpe and M. Abdel-Ghany / Discrimination due to race and gender racial wage differentials, holding gender constant, or have examined gender wage differentials within a given racial group (examples include [3, 4, 11, 17, 20]). Few studies have allowed both race and gender to vary [7, 8]. This paper uses a wage decomposition method introduced by Cotton [8] to examine the components of average wage differentials in the youth labor market, letting both race and gender vary. Cotton's efforts, however, did not address the influence of sample-selection bias on the size of these differentials and the impact of varying the assumptions of the nondiscriminatory wage structure. Both of these issues are examined in this study. 2. Theoretical model The human capital model of wage determination developed by Becker [1,2] and Mincer [19] provides the basis for the general theoretical model used in this study: \nWi = a + bxi-\-ei. (1) In this model, the natural logarithm of the hourly wage rate of the i-th worker (ln Wi) is regressed on a set of variables representing human capital endowments and factors that influence labor demand (a;,). The portion of the log wage not explained by either human capital endowments or labor demand factors is attributed to discrimination. Thus, discrimination is captured and quantified in the error term, ei, which is assumed to follow a normal distribution. Clearly, the size of this component will depend on the quality of model specification and level of measurement error [15]. Without discrimination, whites and blacks (or males and females) would be perfect substitutes in production and any wage differential would be attributed to skill differential alone [9]. Thus, nonzero differences in log wages between two different groups of wage earners which remain after controlling for human capital endowments and labor demand factors imply one group has a relative advantage over the other in the labor market. Differences in log wages between two separate groups of wage earners can be partitioned into three distinct components [9]: K K j=0 The left-hand side of this equation is the difference in wages between the advantaged group and the disadvantaged group. This difference is composed of a skill differential between males (or whites) and females (or blacks) valued in D.L. Sharpe and M. Abdel-Ghany / Discrimination due to race and gender 45 absence of discrimination Z^^o^^'C^T ~ ^ j ) ' ^ favored group treatment advantage YLj=Q^3{^J ^ i ^ ^) ~ ^j)' 3"'^ 3 disfavored group treatment disadvantage ^* represents the nondiscriminatory wage structure. 3. Empirical model Four wage equations were estimated using data from the 1984 Youth Cohort of the National Longitudinal Survey (NLS) of Labor Market Experience. There were 1527 white males, 1128 white females, 477 black males, and 351 black females. All respondents in this study were between 19 and 26 years of age and employed at least part time. Analysis focused on those in this group that were employed full time. White young men received the highest mean hourly wage (geometric mean) at $6.37, while black young women received the lowest at $4.71. The mean hourly wage for black young men and white young women was $5.46 and $5.18, respectively. The empirical model corresponding to equation (1) was: \nW = a + bxi ( z = 1,2,3,...,31), (3) where: Xi is educational attainment measured as years of schooling completed; X2 is job tenure measured as experience with current employer in terms of number of weeks employed; x-j is knowledge of the world of work measures as respondent's score on a test of knowledge of different occupations; X4 is the size of the labor force in the respondent's area of residence (rural versus urban); 0:5 is employment in the public sector; xe is wage determination by collective bargaining; xy is a dummy variable indicating student status; xg... x\Q are dummy variables indicating region of residence; x\i...xig and X20 •ic.ii are dummy variables representing specific occupations and industries of employment, respectively. Human capital endowment is measured by educational attainment, time on the job, and knowledge of the world of work. Remaining independent variables measure aspects of the structure of labor demand. Using the same set of explanatory variables, equation (3) was estimated separately for white males, black males, white females, and black females. Chow tests [6] confirmed wage structures were significantly different for these comparisons: white male to black male, white male to white female, wbite male to black female. 46 D.L. Sharpe and M. Abdel-Ghany / Discrimination due to race and gender Table 1 Mean values and regression coefficients for selected human capital and labor market characteristics on hourly wage rates of white and black male youth White Variables Educational attainment Job tenure Knowledge of world of work Rural residence Govemment employment Collective bargaining Student Region: Northeast North Central West South Occupation: Managerial/professional Sales Craft Technical Operative (assemblers) Operative (transp.) Laborer (nonfarm) Farm laborer Service laborer Clerical Industry: Wholesale trade Public administration Entertainment and recreation serv. Construction Agriculture Personal services Professional and related serv. Business and repair services Financial, insurance. real estate Transp., communication. utilities Mining Manufacturing ' Retail trade Black Mean values 12.6950 224.3200 6.8513 0.1919 0.2502 0.1794 0.7924 Regression coefficients 0.0359'" -0.0015 0.0268'" -0.2037" -0.0305' 0.2807'" 0.0852'" Mean values 12.1890 197.0800 5.0943 0.1216 0.1719 0.3270 0.7107 Regression coefficients 0.0634" 0.0008 0.0247" -0.0903 -0.0118 0.2659"' -0.0897' 0.1991 0.3124 0.1709 0.0109 -0.0548' 0.1392'" 0.1824 0.1656 0.0191 0.0552 -0.0149 0.3111'" - - - - 0.1310 0.8055 0.2528 0.0602 0.1035 0.0661 0.0982 0.0426 0.0891 - 0.1479'" 0.0693 0.0817' 0.3234* 0.0347 -0.0541 -0.0617 -0.1243 -0.0472 - 0.0818 0.0419 0.1845 0.0210 0.1195 0.0713 0.1614 0.0189 0.2159 - 0.1697' -0.0547 0.0853 0.1535 0.0583 0.0616 -0.0436 0.1203 -0.1250 - 0.0419 0.0393 0.1184' 0.1264* 0.0273 0.0524 0.0148 0.0689 0.0164 0.1054 0.0426 0.0282 0.0670 0.2633*** -0.1243 -0.2055'" 0.0105 0.1111 0.0189 0.0461 0.4188** 0.0111 0.1203 0.0404 0.0596 0.0726 0.0881 0.0283 0.0838 0.1461*** 0.1132 0.0116 0.0255 0.2087*" 0.0273 0.1812 0.0576 0.0295 0.3222 0.2434*** 0.4153*** 0.2106*** - 0.0587 0.0147 0.2977 - -0.0210 0.2652 0.1509" - - D.L. Sharpe and M. Abdel-Ghany /Discrimination due to race and gender Table 1 (Continued) White Variables \ Constant B} Sample size Ln hourly wage Mean hourly wage (geometric mean) Mean values -0.4902 I.O 0.2650' •* 1527 6.4572 $6.37 Black Regression coefficients 1.7716* 6.7480* •* Mean values -0.5387 1.0 Regression coefficients 0.1483 5.1940*" 0.2760* •• 477 6.3031 $5.46 * Significant at the .10 level. **Significant at the .05 level. ***Significant at the .01 level. Table 2 Mean values and regression coefficients for selected human capital and labor market characteristics on hourly wage rates of white and black female youth White Variables Black Mean values 13.1340 217.4700 6.7952 0.1551 0.2083 0.1268 0.8502 Regression coefficients 0.0584*** -0.0017 0.0235*** -0.2645** -0.0608** 0.0722* -0.0399 Mean values 12.94 186.94 5.3732 0.0912 0.2707 0.2222 0.8889 Region: Northeast North Central West South 0.1747 0.2748 0.1640 - 0.0851** -0.0208 0.1439*** - 0.1282 0.1225 0.0798 - 0.0042 0.0135 0.1043 - Occupation: Managerial/professional Sales Craft Technical Operative (assemblers) Operative (transp.) Laborer (nonfarm) Farm laborer Service laborer Clerical 0.2012 0.0860 0.0443 0.0602 0.0629 0.0035 0.0284 0.0080 0.1764 - 0.1128** . 0.0647 0.0460 0.1624** 0.0105 0.3368 -0.0002 0.1416 -0.0378 - 0.1396 0.0769 0.0456 0.0684 0.1083 0.0142 0.0313 0.0030 0.2023 - 0.1374* -0.0532 0.0311 0.2626** 0.0282 0.2451 0.0839 -0.4910 -0.0728 - Educational Attainment Job tenure Knowledge of world of work Rural residence Govemment employment Collective bargaining Student Regression coefficients 0.0348 0.0030 0.0361*** -0.0088 -0.0583 0.1510** -0.0720 47 48 D.L. Sharpe and M. Abdel-Ghany /Discrimination due to race and gender Table 2 (Continued) White Industry: Wholesale trade Public administration Entertainment and recreation serv. Construction Agriculture Personal services Professional and related serv. Business and repair services Financial, insurance. real estate Transp., communication. utilities Mining Manufacturing Retail trade A Constant Sample size Ln hourly wage Mean hourly wage (geometric mean) Black Mean values Regression coefficients Mean values 0.0284 0.0505 0.1119 0.1757" 0.1709 0.0940 -0.1266 0.2613' 0.0168 0.0142 0.0133 0.0745 -0.0460 0.2168' -0.4767 -0.6319*** 0.0114 0.0030 0.0057 0.0883 0.1808 0.3861 0.2288 -0.2968" Variables Regression coefficients 0.2598 0.0706 0.2792 0.1192 0.0665 0.1181* 0.0456 0.0654 0.0851 0.0798 0.0570 0.1487 0.0417 0.0071 0.2012 - 0.2100* 0.3677' 0.1018' - 0.0598 0.0028 0.2308 - 0.3615"' 0.3129 0.1140 - -0.5076 1.0 0.3315* »• 1128 6.2492 $5.18 1.7684 6.5649'" -0.5654 1.0 -0.9511 4.3217" 0.3343* 351 6.1541 $4.71 'Significant at the .10 level. "Significant at the .05 level. ***Significant at the .01 level. black male to white female and black male to black female. Wage structures for white females and black females were not significantly different. The mean values of these variables and their regression coefficients for the young men and for the young women are reported in Table 1 and Table 2, respectively. Cotton [9] points out that variations in female employment patterns due to family responsibilities suggest it is important to consider the influence of marital status on labor market participation. Data limitations did not permit inclusion of this variable in this study. However, the impact of this omission is, perhaps, not as great among the age group included in this study as it would be among older workers. For each wage structure compared, four different models were estimated. Two models focused on the issue of selection bias, while the other two models fo- D.L Sharpe and M. Abdel-Ghany / Discrimination due to race and gender 49 cused on the impact of assumptions made regarding the nondiscriminatory wage structure. Adjustment for selection bias. Discrimination, along with government welfare and transfer programs, can affect the number of youth securing full time employment [22]. Assuming labor supply schedules are upward sloping, employment of a group facing discrimination would fall. Workers in this group who would accept nondiscriminatory wages will not accept employment at the lower, discriminatory offer wage, especially when government welfare and transfer programs can provide access to at least a minimal level of consumption. It is hypothesized that neglecting to consider sample-selection bias would result in an underestimation of wage differentials when an advantaged group is contrasted with a disadvantaged group. To test tbis hypothesis, A was introduced as a regressor in the wage equations for full time workers (equation (3)) to correct for selection bias. This correction was calculated according to a procedure developed by Heckman [12, 13]. Impact of nondiscriminatory wage structure assumption. The nondiscriminatory wage structure, identified as B* in equation (2), is not observed but may be estimated given one is willing to make certain assumptions about tbe nature of B*. Cotton [9] assumes, given discrimination, B* is bounded above by the wage structure of the advantaged group (who have an overstated wage) and bounded below by the wage structure of the disadvantaged group (who have an understated wage). The nondiscriminatory wage structure is assumed to be close to the wage structure prevailing for white males. He proposes B* is a linear function of the wage structure of the groups included in tbe analysis weighted by the proportions of each group employed full time in the labor market: B' = /wmB™ + /bmS*"" -f /wfB-f + /bfB''f. (4) In 1984, wbite male youth comprised 68.9% of the workers in this category, black male youth 3.8%, white female youth 23.4%, and black female youth 1.8% [23]. Reimers [21] has argued that the nondiscriminatory wage should be assumed to be midway between tbe highest and lowest wages received. In this study, the nondiscriminatory wage falls midway between the mean hourly wages received by white males ($6.37) and black females ($4.71). Rather than using labor market proportions, B* is weighted proportionate to the difference between the wage received and the wage that would have been received in the absence of discrimination. The resulting estimate of B* is: B* = (.3952 X Bwm) + (.1714 x .Btm) + (.0381 x (5) -{-(.3952 X ) 50 D.L. Sharpe and M. Abdel-Ghany / Discrimination due to race and gender Table 3 Decomposition of wage differentials of white and black male youth (percentage of wage differentials in parentheses) Model Wage differential Skill differential 1 0.1540 (100%) 2 0.1040 (67.5%) White male treatment advantage 0.1778 (115.5%) Black male treatment disadvantage -0.1278 (-83.0%) 0.1183 (100%) 0.0485 (41.0%) 0.1770 (149.6%) 3 0.1540 (100%) 0.1104 (71.7%) 0.0726 (47.1%) 4 0.1183 (100%) 0.0590 (49.9%) 0.0742 (62.7%) -0.1072 (-90.6%) -0.0290 (-18.8%) -0.0149 (-12.6%) Models used in this study. For each gender and race comparison that was statistically significant according to the Chow test, four separate models were constructed. All four models follow Cotton's general model outlined in equation (2). In the first two models. Cotton's assumptions are utilized in the calculation of B*. The latter two models, in contrast, use Reimers' assumption regarding the nondiscriminatory wage to calculate B*. Model 1 and model 3 incorporate a correction for selection bias, while model 2 and 4 exclude this correction. 4. Results The decomposition results for the 91 cent average wage differential between white men and black men are reported in Table 3. When selection bias is taken into account, approximately two-thirds of the differential can be attributed to white male skill advantage evaluated in absence of discrimination. Ignoring selection bias drops the percentage of wage differential attributed to skill differences to almost 50% in model 4 and 41% in model 2. In dollar terms, between 37 cents and 65 cents of the 91 cent wage differential is explained by nondiscriminatory skill differences. The remaining difference is attributed to discrimination. Examination of the white male treatment advantage and black male treatment disadvantage across all four models reveals a wage premium paid to black males. In the absence of discrimination, the average wage for blacks would have been approximately 1% to 12% lower than it actually was. Note this premium is much more pronounced for models 1 and 2 than for models 3 and 4, suggesting wage decomposition results are very sensitive to the assumptions underlying calculation of B* for these two groups. Table 4 presents the decomposition results for white males compared to white females. For each of the four models, approximately one-forth of the $1.19 wage D.L. Sharpe and M. Abdel-Ghany / Discrimination due to race and gender 51 Table 4 Decomposition of wage differentials of white male and female youth (percentage of wage differentials in parentheses) Model Wage differential Skill differential 1 0.2079 (100%) 2 0.0534 (25.7%) White male treatment advantage 0.1778 (85.5%) White female treatment disadvantage -0.0233 (-11.2%) 0.2078 (100%) 0.0550 (26.5%) 0.1770 (85.2%) -0.0242 (-11.7%) 3 0.2079 (100%) 0.0726 (34.9%) 0.0842 (40.5%) 4 0.2079 (100%) 0.0511 (24.6%) 0.0512 (24.6%) 0.0742 (35.7%) 0.0825 (39.7%) Table 5 Decomposition of wage differentials of white male and black female youth (percentage of wage differentials in parentheses) Model Wage differential Skill differential 1 0.3225 (100%) 2 0.1129 (35.0%) White male treatment advantage 0.1778 (55.1%) Black female treatment disadvantage 0.0318 (9.9%) 0.3029 (100%) 0.1275 (42.1%) 0.1770 (58.4%) -0.0016 (-0.53%) 3 0.3225 (100%) 0.1342 (41.6%) 0.0726 (22.5%) 0.1157 (35.9%) 4 0.3030 (100%) 0.1322 (43.6%) 0.0742 (24.5%) 0.0966 (31.9%) differential is explained by nondiscriminatory skill differences of wbite males. In models 1 and 2, it would appear wbite females receive 2% bigher wages than tbey would have received in absence of discrimination, a very slight wage premium indeed. In these models, white male treatment advantage explains about $1.01 of the $1.19 wage differential. Models 3 and 4, in contrast, suggest white women receive almost 8% lower wages than they would have received in absence of discrimination. Here, white male treatment advantage explains only about 42 cents of the $1.19 differential. The wage difference between white males and black females reported in Table 5 was the largest of all groups compared ($1.66). This comparison is one of two possible cross race and cross gender comparisons. For model 1 and 2, skill differences and white treatment advantage explained over 90% of this wage difference. Black female treatment disadvantage was substantially higher in models 3 and 4 at 36% and 32%, respectively. In dollar terms, black female wages were 53 to 52 D.L. Sharpe and M. Abdel-Ghany / Discrimination due to race and gender Table 6 Decomposition of wage differentials of black male and white female youth (percentage of wage differentials in parentheses) Model Wage differential Skill differential 1 0.0896 (100%) 2 0.0066 (7.4%) Black male treatment advantage 0.1072 (119.6%) White female treatment disadvantage -0.0242 (-27.0%) 0.0539 (100%) -0.0506 (-93.9%) 0.1278 (237.1%) -0.0233 (-43.2%) 3 0.0895 (100%) -0.0079 (-8.8%) 0.0149 (16.7%) 0.0825 (92.2%) 4 0.0539 (100%) -0.0593 (-110.0%) 0.0290 (53.8%) 0.0842 (156.22%) Table 7 Decomposition of wage differentials of black male and female youth (percentage of wage differentials in parentheses) Model Wage differential Skill differential 1 0.1685 (100%) 2 0.0089 (5.3%) Black male treatment advantage 0.1278 (75.9%) White female treatment disadvantage 0.0318 (18.9%) 0.1846 (100%) 0.0790 (42.8%) 0.1072 (58.1%) (-0.87%) 3 0.1686 (100%) 0.0239 (14.2%) 0.0290 (17.2%) 0.1157 (68.6%) 4 0.1847 (100%) 0.0732 (39.6%) 0.0149 (8.1%) 0.0966 (52.3%) -0.0016 60 cents lower than they would otherwise have been in absence of discrimination. White male treatment advantage accounted for almost twice as much of the wage differential in models 1 and 2 (55% and 58%) compared to models 3 and 4 (23% and 25%). However, across all four models, skill differences accounted for close to 40% of the wage differential. The other cross race and cross gender comparison in this study, black males and white females, had the smallest wage differential ($0.28) of all comparisons made. Results of the wage decomposition are reported in Table 6. For models 2, 3, and 4, skill differences were negative. This result suggests gender discrimination predominates over racial discrimination. For, although mean human capital endowments of black males generally lag behind white females, on average, black males receive a higher wage than white females. Note, the magnitude of the negative skill differences are more pronounced for the two models (model 2 and 4) which omitted the correction for selection bias. The size of the skill differential is D.L. Sharpe and M. Abdel-Ghany /Discrimination due to race and gender 53 considerably smaller in model 3 where selection bias bas been taken into account. In models 1 and 2, the black male treatment advantage was much larger than in models 3 and 4, again indicating the impact of varying the assumptions underlying calculation of B*. White females appear to receive a sizable wage premium in models 1 and 2, getting 27% (model 1) to 43% (model 2) more in wages tban they would have received in the absence of discrimination. This picture is, however, markedly different in models 3 and 4 which show the wage differential between black males and white females dominated by treatment disadvantage experienced by white females. The wage differential between black men and black women reported in Table 7 is next to the smallest of all the groups compared at 75 cents. Unlike other comparisons, no consistent pattern emerged from the four models. For this comparison more so than any other, each of the models used to decompose the wage differential tell very different stories. Skill differential accounted for a low of 5% (model 1) to a high of 43% (model 2) of the wage difference. Model 2 suggests black females have an almost negligible treatment advantage compared to black males in the labor market. But, according to model 3, average wages received by black females are approximately 69% less than they would have been in the absence of discrimination. The advantage of being a black man compared to a black woman in the labor market ranged from a high of approximately 75% of tbe wage differential (model 1) to a low of around 8% of the wage differential (model 4). 5. Discussion During the past several decades in America, desegregation laws have been put into effect and equal opportunity regardless of race or gender has been stressed. These social forces should have the effect of narrowing skill differentials and eliminating treatment advantages awarded to certain racial or gender groups, especially for youth just beginning their participation in the labor force. Results of this study indicate differences in average log wages persist even after controlling for differences in human capital. Differences in average log wages were decomposed for four separate racial and gender comparisons. For every comparison except white male to black male, skill differentials accounted for less than half of the difference in average log wage. This result suggests differential treatment by race and gender persists in the labor market, accounting, in general, for over half of the differences in average log wage. Comparisons across race, holding gender constant, indicate wbites receive a sizable treatment advantage, regardless of the model used to decompose tbe wage differential. Comparisons across gender, holding race constant, reveals a male treatment advantage for both wbite and black males. This advantage was over twice as large for models 1 and 2 as for models 3 and 4. The size and direction of female treatment disadvantage varied. White females received a wage premium 54 D.L. Sharpe and M. Abdel-Ghany / Discrimination due to race and gender for models 1 and 2, black females received the same only for model 2 and only for a negligible amount. Female treatment disadvantage was markedly greater for models 3 and 4 than for models 1 and 2. Examination of results of cross race and cross gender comparisons suggests gender discrimination exceeds racial discrimination in the youth labor market. Selection of a given model as a basis for the decomposition of wage differentials did made a difference. Across virtually all comparisons, correcting for selection bias widens the discriminatory wage differential. This finding supports the assertion in previous research that neglecting to correct for selection bias would lead to misleading wage comparisons [13, 22]. For some comparisons, the change was negligible. When comparing average wages of white males with white females, for example, without correcting for selection bias, the white female treatment disadvantage accounted for 39.7% of the wage differential in model 4. When the selection bias correction is present in model 3, white female treatment disadvantage increased to 40.5%. In other comparisons, the change was more pronounced. For instance, comparing average wages between black men and black women, accounting for selection bias increased the black female treatment disadvantage from 52.3% to 68.6% (in model 4 and 3, respectively). Changing assumptions underlying B* also influenced the final percentages of the wage decomposition attributed to skill differential, treatment advantage, and treatment disadvantage. When the assumption is made that the nondiscriminatory wage structure resembles the wage structure of white males, the treatment advantage is generally over twice as large as it is when the nondiscriminatory wage is assumed to be midway between the highest and lowest wages received. 6. Conclusion Two conclusions may be drawn from this study. First, the results indicate that wage discrimination in the youth labor market is due more to gender differences than to racial differences. No difference was found between the wage structures for black and white females, indicating no racial discrimination exits between these two groups. Comparing females to males, males received higher wages than they would have in absence of discrimination, regardless of race. In fact, although white females had better human capital endowments than black males, they received less wages to compensate them for their work in the labor market. Single jeopardy rather than double jeopardy is at work here. 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