metadata: authors: 0: author: Panagides, Alexis
1: author: Patrinos, Harry Anthony
2: author: DEC
count: Mexico
docna: 0: docna: Union - nonunion wage differentials in the
            developing world : a case study of Mexico
docty: Policy Research Working Paper
subtopic: Human Rights,Labor Markets,Educational Sciences,Gender and Development,Rural Labor Markets
teratopic: Health, Nutrition and Population
abstracts: cdata!: Union-nonunion wage differentials have
            been extensively studied by labor economists, but for lack
            of data on the developing world the study has been confined
            largely to the industrial world.  This paper is one of the
            first attempts to empirically examine those differentials in
            a developing country. The authors find that union-nonunion
            wage differentials in Mexico have many of the same patterns
            as those in industrial nations.  But there are marked
            differences.  Based on a household survey in 1989, the
            authors find that: (i) overall, the union-nonunion wage gap
            is 10.4 percent; (ii) unions have a positive impact on the
            earnings of employed women and indigenous people; and (iii)
            organized labor in Mexico's northern states is
            considerably weaker in collective bargaining strength than
            it is elsewhere in Mexico.
geo_reg_key: 119228,517191
repnme: repnme: Union - nonunion wage differentials in the
            developing world : a case study of Mexico
display_title: Union - nonunion wage differentials
            in the developing world : a case study of Mexico
listing_relative_url: /research/1994/03/698534/union-nonunion-wage-differentials-developing-world-case-study-mexico
topicv3: Labor Markets m1326488 855,Education m1327048 470,Gender m1327621 615,Discrimination m1505707 3379,Wage Gap m1582439 4439
publishtoextweb_dt: 2010-07-01T00:00:00Z
historic_topic: Health, Nutrition and Population
origu: UNKNOWN
no_of_pages: 40
model_extractions: [ POLICY RESEARCH WORKING PAPER 1269

# Summary findings

Union-nonunion wage differentials have been extensively studied by labor economists, but for lack of data on the developing world the study has been confined largely to the industrial world. This paper is one of the first attempts to empiricaily examine those differentials in a developing country.

Panagides and Patrinos find that union-nonunion wage differentials in Mexico have many of the same attributes and show many of the same patterns as those in industrial nations. But there are marked differences.

Based on a household survey in 1989, Panagides and Patrinos find that:

* Overall, the union-nonunion wage gap is 10.4 percent.

* Unions have a positive impact on the earnings of employed women and indigenous people.

* Organized labor in Mexico's northern statcs is considerably weaker **in** collective bargaining strength than it is elsewhere in Mexico.

This paper-a joint product of the Human Resources OperationsDivision, L.atin America and the Caribbean, Country Department - 11, and the Education and Social Policy Department is part of a larger effort in the Bank to investigate labor markets and labor market institutions in developing economies. Copies of the paper are available free from the World Bank, 1818 H Street NW, Washington, DC 20433. Please contact Ian Conachy, room S 10-022, extension 33669 (35 pages). March 1994.

_The Policy Research Working Paper Series disseminates the findings of uwork in progress to encourage the exchange of ideas about development issues. An objectiveof the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry the names of the authors and should be used and cited accordingly. The findings, interpretations, and conclusions are the authors' own and should not be attributed to the World Bank, its Executive Board of Directors, or any of its member countries._ Produced by the Policy PerParch Dissemination Center
# U-nion-Nonunion Wage Differentials in the Developing World: A Case Study of Mexico

by

## Alexis Panagides and Harry Anthony Patrinos /*

The World Bank 1818 H Street, N.W. Washingtoa, D.C. 20433 The views expressed in this paper are those of the authors and are not to be attributed to the World Bank. The authors wish to thank George Psacharopoulos, Anthony Yezer, Zafiris Tzannatos, Daniel Oks, Alejandra Cox Edwards and Amit Dar for comments on an earlier draft.
# Introduction

Organized labor has long been an important phenomenon in the political, social and economic development of nations, as the relationships between labor, industry and the state have proved critical elements in the creation of modem economies and democracies. As a result of the efforts to better understand these relationships, the study of organized labor has become extensive. One particular area of interest in this study has been the influence of unions on wages. However, previous research was concentrated in developed countries, where the experience of organized labor has been longer and information more readily available.

In recent years the examination of union-nommion wage differentials has increased dramatically, primarily due to the advent of increased computational power, the increased availability of micro-data and new econometric techniques (Hirsch and Addison 1985). Despite unriecedented analytical capability, with regards to the particular issue of unionnonunion wage differentials the literature largely ignores developing nations. Notable exceptions include Moll's study of South African unions (1993), Park's (1991) study of union-nonunion wage differentials in Korea and Standing's (1992) study of unions in Malaysia. The primary cause of this shortfall stems from the lack of adequate data (Nelson 1991). Although many economic surveys are completed each year in developing nations, few contain questions regarding unionization. The 1989 Mexican household survey upon which this paper is based fulfills this requirment. This data, coupled with growing interest in the Mexican labor market fueled by concerns over the North American Free Trade
Agreement (NAFTA), allows a rare and timely opportunity to examine union-nonunion wage differentials for an important developing country.

The purpose of the study is to measure the collective bargaining strength of Mexican organized labor as reflected by its effect on the wage structure, income inequality, and gender and ethnic wage differentials. The paper begins by describing the data upon which the empirical research is based and then discusses the method used in determining the unionnonunion wage differential. The following sections present the results of the empirical analysis. The empirical results discuss various wage equations, variations in the union wage gap, union influence on gender and ethnic wage determination and income inequality. The final section present3 conclusions and indentifies the need for further research.

# **Method**

in recent years the econometric analysis of the union-nonunion wage differential has undergone considerable debate, much of it centering on the apparent endogeneity of union status in the wage equation (Duncan and Leigh 1985). Various simultaneous equation estimators have been devised in the attempt to mitigate the potential bias presented by union selectivity. Selectivity arises partly from the individual worker's choice of union status (Robinson 1989). However, these estimation techniques, though often ingenious, commonly yield implausable results and demonstrate substantial sensitivity to specification (see Ashraf 1990 for greater detail concerning methodological debate).<sup>1</sup> For these reasons, this paper I Simultaneo -s equation techniques were attempted in this study, resulting in the above mentioned difficulties. The results are available from the authors upon request.
will rely on an ordinary least squares (OLS) based method to calculate the union-nonunion wage differential. Although OLS based methods are prone to the aforementioned bias, they are robust. Furthennore, though the nature of the bias induced by endogeneity is unclear (both in magnitude and sign), Lee found it to be upward and smal' ( Lee 1978; see also L:wis 1986).z Analysis of the wage differential in this paper will rely on the estimation of two separate OLS earnings equations, one for each sector. One advantage of this method, unlike single equation OLS methods employing a union dummy variable, is that it allows for differences in the earnings structure. Equation (1) represents the estimated wage equation for the union sector and equation (2) represents the equation for the non-union sector: _InW, =_ XA,. + _V',_ where _LnW_ represents the log of hourly earnigs, the X represents the vector of personal endowments, and (3 represents the vector of estimated regression coefficients. The subscripts u and n indicate the union and non-union subsample. The v represents the error term, while i the ith observation.

2 Though Lewis (1986) was unable to determine the sign or magnitude in his exhaustive study of the union-nonunion wage gap literature, he did suggest that certain theoretical priors would preclude that union selectivity would overestimate the union-nonunion wage differential. Lee (1978) found that correcting for the bias reduced the estimated effect of unions on wages, but only by a modest two percentage points.

3
_(3)_ To estimate the mean logarithmic unic&-nonunion wage differential (or wage gap), equation (b) is constructed (Hirsch and Addison 1986). The unexplained differences in log hourly wage is equivalent to:

- _a_ (-X

The value of _d_ is converted to a percentage value by (1-et) * 100, where e represents the exponential function (Halvorsen and Palmquist 1980). At values below 0.15, _a_ approximates a rate (for example, _d_ = 0.104 10.4 percent). The #,3 (x=u,n) is the vector of estimated coefficients. The X represents the vector of either union, nonunion or all workers' mean characteristics.

Equation (3) estimates that portion of the mean wage gap that is due to factors other than differences in mean characteristics. This aspect is critical to union-nonunion wage gap analysis since this "unexplained" portion comprises not only the influencc of unobserved characteristics and potential wage discrimination on wage rates, but also, in the case of union analysis, the effectiveness of union organization in securing higher wage rates for its members above those offered in the nonunion sector. It should be mentioned that since the portion of the "unexplained" wage gap that accrues to union organization is not separated from the other aforementioned influences, the estimated wage gap reflects only the upper limit of union bargaining strength.

4
While the wage gap can be evaluatWd either at union or nonunion mean characteristics, this study employs all workers' mean characteristics. The use of all-worker means, X=(PX, + (I-P)X,), where P is the proportion of union observations, corresponds to asking the question: for a worker with average characteristics, what is the predicted wage differential between his/her working in the union and nonunion sectors (Hirsch and Addison 1986)?

To test the statistical significance of the wage gap the predicted union log hourly wage of nonunion workers is computed using the estimated union wage structure and nonunion characteristics _(predictedl union InW of nonunion worker =X,$,j3 + v.,)._ The estimated union wages and actual wages of nonunion workers are then tested for statistical difference employing a standard t-test.

# Data

The data used in this analysis come from the 1989 household survey conducted by the the National Institute of Geographical Statistics and Information _(Instituto Nacional de Estadistica Geografia e Informatica),_ known as the National Income and Expenditure Household Survey _(Encuesta Nacional de Ingreso-Gasto de los Hogares)._ The survey covers 11,545 households and contains 57,332 individual observations. The geographical coverage includes each of the 31 Mexican states, representing 260 _municipios_ (counties) and the Federal District. Each household is identified by the state and the _municipio_ in which it is _5_
located. The subsample upon which this report is uased upon is comprised of 9,954 nonagricultural workers ranging from 16 to 65 years of age, with positive labor market earnings.

Although the data used in this paper does possess a variable indicating union status, it does fall short in regard to some issues relevant to union wage gap analysis. One shortcoming is EYe lack of detailed information on non-monetary remuneration. A study by Freeman (1978) found that union workers receive a higher proportion of compensation in nonpecuniary forn than do nonunion workers. Therefore, it should be kept in mind that the wage gap may be greater than indicated since fringe benefits cannot be included in the analysis. Freeman's (1981) analysis indicates that previous estimates of the union wage differential understated the union compensation differential, but only by about two percent (Hirsch and Addison 1986).

Although the Mexican data do not allow for an adequate examination of nonpecuniary compensation, information on the incidence of health insurance coverage among workers is included. DJot surprisingly, the percentage of those with health care coverage among the union subsample is significantly higher than the percentage with coverage in the nomnmion subsample, at 86 and 56 percent.

The mean values for those variables used in the analysis for the entire sample, and for the union and nonunion subsamples separately, are listed in Table 1.

6
**Table 1: Mean Sample Characteristics**

|**Variable**|Total|Union<br>Subsample|Nonunion<br>Subsample|
|---|---|---|---|
|Years of Schooling|8.4|9.7|7.9|
|Experience (years)|18.0|18.7|17.7|
|Hours Worked per Week|44.5|42.2|_45.5_|
|**Education Level**||||
|Prinary|0.35|0.28|0.38|
|Secondary incomplete|0.29|0.28|0.30|
|Secondary complete|0.14|0.20|0.12|
|Tertiary|0.16|0.23|0.13|
|Industrial**Sectors**||||
|Extraction|0.02|0.05|0.01|
|Manufacturing|0.23|0.21|0.24|
|Utilities|0.01|0.02|0.01|
|Construction|0.10|0.04|0.12|
|Commerce|0.14|0.05|0.18|
|Transportation|0.05|0.06|0.04|
|Financiai Services|0.02|0.03|0.02|
|Services|0.42|0.54|0.37|
|_Municipio_Indigenous Percent|2.90|3.01|2.86|
|Nortiern State Residence|0.23|0.19|0.24|
|Male|0.67|0.65|0.67|
|Union Membership|0.30|1.00|0.00|
|Log of Hourly Earnings|7.85|8.07|7.76|
|Actual Hour!y Farnings_(pesos)_|3,522.60|4,076.63|3,298.56|
|Number of Observations|9,954|2,954|7,000|

Source: INEGI (1989).

7
The union membership variable equals 1 for respondents answering in the affirmative to the question, _jEstd usted qflhiado a alguna organizacion laboral o patronal?_ (Are you affiliated with a workers' or enmployers' organization?). The union membership variable indicates that 30 percent of the entire sample claims union membership. This figure closely approximates previous estimates of the proportion of the Mexican labor force unionized in the late 1980s (Nelson 1991). The service sector possesses the majority of unionized labor. The is largely due to the survey's inclusion of the public sector in the service sector category. The average natural log of hourly earnings, defined as the natural log of gross weekly wage rate, including payments in-kind, divided by hours worked per week, reveals substantially higher wage rates among the union than in the nonunion subsample. It is primarily this difference that will be examined in this study.

The _municipio_ indigenous percent variable and the northern state residence variables measure certain regional characteristics. The _municipio_ indigenous percent variable controls for the concentration of the indigenous population and reflects the prooability that a sampled individual is indigenous. Sinc= a specific question concerning indigenous origin was not included in the survey, the percentage of indigenous people recorded for each _municipio_ in the 1990 Census was substituted (INEGI ;990). The nonunion subsample _municipio_ indigenous percentage average of 3.0 percent is slightly higher than the union subsample at 2.9 percent (for further discussion regarding this variable, see Psacharopoulos and Patrinos 1993).

8
One of the most dynamic areas of Mexico is the northern region bordering the United States. Due to the political and economic importance of this region, especially in light of NAFTA, the analysis controls for northern state residence. Northern state residence is defined by residence in one of the six states along the United States-Mexico border: Baja California Norte, Sonora, Chihuahua, Coahuila, Nuevo Leon and Tampulinas. For the nonunion subsample, 23 percent of the observations were from these northem states, as opposed to 19 percent in the union subsample.

Empirical Findings _Union AMembership_ Table 2 presents the results of a multivariate logit model which expresses the probability of someone being a union member as a function of various characteristics such as education level, gender and so on. The reported coefficients are partial derivatives indicating the change in the probability of union membership relative to a unit change in one of the independent variables.

The probability cf unionization increases until secondary schooling is completed, whereupon further education has no additional impact on the probabilities of union membership. Years of experience increases the probability of union intmbership, albeit at a slightly diminishing rate. The coefficient on northern state residence reveals that labor in the north is 4.6 percent less likely to organize than labor elsewhere in the country.

9
Unions do not seem to be biased against women or indigenous people in the selection process. The probability of union membership is lower for men than for women. This finding is ot completely surprising in the context of the additional analysis below that reveals substantially lower union wage differcntials (and thus lower union membership incentive) for men than for women. However, this finding is surprising in that it is counter to many studies in developed nations, where women are found to be significantly less likely to be union members than are men (Hirsch and Addison 1985). The difference in observations may partly be explained by the relatively smaller observed union wage gap differences between women and men in more developed countries. This point is discussed in greater detail below. The _municipio_ indigenous percent variable is the only nonsignificant factor. Given the large wage incentive to enter the union sector discussed below, this nonsignificance is slightly surprising. Additionally, cultural factors may play a roll in the propensity of unionization among indigenous people.

10
# **Table 2: Determinants of Union Membership (Logit)**

|**Variable**|**Marginal Effect (%)**|
|---|---|
|**Education level**(residual=**tio**education)||
|Primary|25.30*<br>(7.4)|
|Secondary Incomplete|39.52*<br>(11.1)|
|Secondary Complete|54.08t<br>(14.7)|
|Tertiary|54.63::<br>(14.9)|
|Experience|2.09*<br>(14.7)|
|Experience squared|-0.03*<br>(10.0)|
|Northern State Residence|-4.55*<br>(3.9)|
|Male|-3.50_*_<br>(3.5)|
|_Municipio_indigenous percent|0.10<br>(1.7)|
|Constant|-3.69|
|N|9,939|
|Model Chi-square|758.35|
|Mean of Dependent Variable|0.297|

Source: INEGI (1989). Note: Numbers in parenthesis are t-values. t indicate **s** ignificant at the 99% level.

11
# _Union-Nonunion Wage Differential_

To begin examination of the union-nonunion wage differential, two wage equations are estimated, one for each sector. The dependent variable is the log of hourly earnings, constructed by taking the log of the monthly wage rate divided by the hours worked per month {ln(W/brs)). The estimated equations including variables reflecting education, represented here as years of schooling splined into four dummy variables, experience (ageschool-6) and its transformation. Additional independent variables include gender, geographical region, _municipio_ indigenous concentration and industrial sector. Table 3 lists the results of the union and nonunion earnings equations estimates and the marginal contributions of the variables to the overall wage gap.

12
# Table 3: Union and Non-union Hourly Earnings Functions

||Sector||Marginal<br>Contribution|
|---|---|---|---|
|Variable|Union|Nonunion||
|Education leveP||||
|Primary|0.320 t<br>(3.8)|0.249t<br>(6.8)|0.025|
|Secondary Incomplete|0.532t<br>(6.1)|0.621t<br>_(15.5)_|40.027|
|Secondary Complete|0.882t<br>(9.8)|0.961t<br>(21.6)|-0.011|
|Tertiary|1.226t<br>(13.6)|1.425t<br>(32.3)|-0.031|
|Experience|0.038 *<br>(12.1)|0.055t<br>(24.5)|-0.302|
|Experience squared|-0.001t<br>(7.8)|-0.001*****<br>(19.5)|0.176|
|Northern State|0.123t<br>(4.7)|0.258t<br>(13.9)|-0.031|
|Male|0.063<br>(0.1)|0.161t<br>(9.1)|-0.066|
|_Municipio_Indigenous Percent|0.001<br>(0.6)|40.008t<br>(7.8)|0.026|
|Industrial Sectorsb||||
|Industrial Manufacturing|-0.285<br>_(5.6)_|-0.275 $ (3.4)|-0.003|
|Utilities (electricity & water)|0.019<br>(0.2)|40.239<br>(1.8)|0.003|
|Construction|-0.197t<br>(2.8)|-0.362t<br>(4.4)|0.016|
|Commerce|-0.283t<br>(4.4)|40.318t<br>(3.9)|_0.005_|
|Transportadon|-0.045<br>(0.7)|-0.212 t<br>(2.4)|0.008|
|Financial Services|-0.034<br>(0.4)|0.075<br>(0.8)|-0.003|
|Services|-0.059|40.322 t|0.107|
||(1.2)|(4.0)||
|Constant|6.967|6.757|0.210|
|Adjusted R<sup>2</sup>|0.324|0.303||
|N|2,793|6,907||
|Adjusted Wage Gap|||0.104t|

Source: INEGI (1989) Notes: t significant at the 95% level. t signifcant at the 99% level. a Residual is no education. I Residual sector is extraction. Numbers is parenthesis are t values. , is the estimated coefficient. u and n subscripts represent union and nonunion subsamples, respectively. it is the full sample weighted variable mean.

13
As Table 3 indicates, educational attaimnent has a significant positive impact on earnings. However, the form of this impact differs between the two sectors. In the union sector, the returns to education profile is flatter than in the nonunion sector. In the union sector, the difference in returns to education between those with some primary schooling versus those with tertiary education is less than the corresponding comparison in the nonunion sector. The negative marginal contribution found among those with greater than primary education reflects a wage disincentive for those with more education to entering the union sector.

Other personal and regional characteristics such as experience, gender and _municipio_ indigenous concentration also show marked differences between sectors. Returns to labor market experience are greater in the noniunion sector, contributing a _5.5_ percent wage increase per year of labor market experience versus 3.8 percent in the union sector. The -0.302 marginal contribution of experience reveals that a large portion of the wage gap favoring the nonunion sector is due to the greater experience premiums in that sector than in union sector. Furthermore, as Figure 1 shows, the effect of experience on union-nonunion wage differences varies in a distinct 'U' pattern, as the differential initially decreases then eventually increases with greater experience. The minimum wage differential on the wage gap-experience profile occurs at around 23 years of experience.

14
- **Figure 1: Experience Union Wage Gap Profile**

<!-- Start of picture text --> Estimated Union Wage Gap<br>0.26<br>0.2<br>0.15<br>0.1<br>0.05<br>0<br>2 46 6 10 1 1262022242628303234363840<br>Years of Experience<br><!-- End of picture text --> Source: Estimated from results in Table 3.

The coefficients for gender and ethnicity reveal a significant difference between the union and nonunion sectors with regards to gender and ethnic wage differentials. In the nonunion sector, men enjoy a 17.5 percent wage advantage over women, whereas in the union sector the coefficient for gender is nonsignificant, highly suggestive of greater gender equality in the union sector than in the nonunion sector. Similarly, wage equality for indigenous people seems to be potentially greater in the union sector. The coefficient of the _municipio_ indigenous percent variable in the nonunion sector equation reveals a -C.8 percent earning disadvantage for each percent of indigenous population within a _mwnicipio,_ whereas the same coefficient in the union sector equation is nonsignificant. Variations in the wage differential due to gender and indigenous probability are examined more closely in latter sections.

15
The dummy variable controlling for northern state residence reveals further differences between the union and nonunion sectors. The northern state variable shows greater wage gains accruing to northern state residence for those in the nonunion sector than in the union sector, at 29.4 versus 13.1 percent. The marginal effect reveals a -3.1 percent erosion of potential union bargaining strength. In the rapidly growing northern region of Mexico along the United States border, this dispanty may be due to several factors. Among other reasons, it may reflect regional factors that are unfavorable to unions, namely, an unrestricted labor supply and/or highly competitive industries. Union-nonunion wage gaps are difficult to maintain where substitution by firms in production and consumers in consumption is most easy. A large labor supply fueled by heavy migration is likely to inhibit union bargaining power by enabling industry to more easily substitute union labor with nonunion labor. Thus the more elastic supply of labor in the northern border region may have much to do with explaining the reduction in the union wage gap (Fatemi 1988). Similarly, highly competitive industries forced to operate at or near cost also inhibit union bargaining power by diminishing room to negotiate wage increases. Demand effects may result in a shift away from more costly products from the union sector (assuming unions raise prices) to relatively less costly products from the nonunion sector. As long as labor supplies in the nonunion sector are not perfectly elastic, demand effects will put upward pressure on wages in the nonunion sector and thus mitigate the union wage gap (Hirsch and Addison 1986). However, as will be discussed in greater detail below, the difference in estimated coefficients is likely to be capturing the higher nonunion wage rates in the northern region compared to nonunion wage rates in the rest of the country. The union wage gap 16
estimated solely among northern states is -0.02, revealing a potential wage disadvantage in union membership.

The variables controlling for economic sector reveal increased inter-sectoral wage equality in the union sector than in the nonunion sector for the nation as a whole. Workers in all industries, except manufacturing, finance and utilities, improve their wage status, in relation to the omitted category (extraction), once unionized. In the union sector, the industry with the greatest wage disadvantage vis-a-vis the extraction industry is manufacturing, with a -33.0 percent wage disadvantage. It is interesting to note that the marginal contribution of industrial manufacturing, -0.3 percent, reveals a possible nonunion wage advantage. In the nonunion sector, services are the most disadvantaged, at -38.0 percent. However, in the union sector, services wage disadvantage is greatly reduced, at - 6.0 percent, which is reflected in the substantial 10.7 percent marginal contribution to the overall union-nonunion wage differential.

The summation of the marginal contributions equals the overall union-nonunion wage differential. From the two estimated earnings equations, the wage gap (eq. 3) is measured at nearly 10.4 percent, indicating that while controlling for certain wage generating characteristics, those in the union sector earn 10.4 percent more in hourly wages than do those in the nonunion sector. This value is somewhat less than the average value of 14 percent derived by Lewis (1986) in his review of union-nonunion wage diffcrentiabs in the United States covering the period 1967 to 1979. Furthermore, it is below the lowe;st average 17
yearly value of 0.11 observed during the same time span (Lewis 1986). Recalling the historical context of organized labor in Mexico during the 1980s, a period of particular difficulty induced by recession coupled with government austerity measures, this relatively smaller differential is not surprising (Middlebrook 1989).

The average wage differentials for individuals categorized by gender, experience and education are presented in Table 4. It is clear that working women enjoy a greater wage advantage in the union sector than do men of corresponding education and experience. As the earnings equations coefficient for gender would indicate, there is, on average, a 9.8 percentage point difference between male and female wage differentials. With regard to experience, the aforementioned 'U' pattern in the wage gap is clearly observed, as the differential first decreases, then increases with more experience. Furthermore, unionization tends to be most advantageous for those with less education. A clear trend of decreasing wage differentials exists as educational level increases. In **the** case of men with more than seven years of schooling and more than ten years work experience, unionization may actually be disadvantageous, indicating that men in this category earn more, on average, in **the** nonunion sector.

18
# Table 4: **Average Wage Differentials () by Gender, Experience and Education**

||||Educatio|n (years)||
|---|---|---|---|---|---|
|Gender|Experience (years)|0 to 3|3+ to 7|7+ to 12|12+|
|Male|0 to 10|0.21|0.18|0.05|-0.04|
||10+ to 20|0.12|0.13|-0.03|-0.08|
||Above 20|0.20|0.15|-0.01|-0.08|
|Female|0 to 10|..|0.27|0.15|0.11|
||10+ to 20|0.26|0.20|0.11|0.09|
||Above 20|0.33|0.26|0.14|0.09|

Source: Estimated from above results in Table 3. Notes: .. indicates small cell count.

The examination of the wage differential by the probability of being an indigenous person is listed in Table 5. Those living in _municipios_ with more than a ten percent indigenous population experience greater wage advantages in the union sector than do those with similar education and experience in less indigenous _municipios._ For example, for those with 10 to 20 years experience, and 7 to 12 years of schooling, the union-nonunion wage differential is nearly 31 times higher for those in more indigenous areas than in less indigenous areas.

19
**Table** 5: **Average Wage Differential () by Indigenous** _Municipio_ **Category, Experience and Education**

|**Ethnicity**|**Experience (vears)**|0 to 3|Educatio<br>3+ to 7|n (vears)<br>7+ to 12|12+|
|---|---|---|---|---|---|
|Non-indig.|0 to 10|0.20|0.18|0.07|0.0|
||10+ to 20|0.14|0.13|0.01|**_-0.05_**|
||Above 20|0.21|0.17|0.03|-0.05|
|Indigenous|0 to 10|..|0.52|0.35||
||10+ to 20|0.37|0.41|0.31||
||Above 20|0.43|0.40|0.31||

Source: Estimated from results in Table 3.

Notes: .. indicates small cell count. **a** Non-indigenous indicates _municipios of_ 10 percent and under indigenous population. Indigenous indicates _municipios_ of over 10 percent indigenous.

_Wage Dispersion and Income Inequality_ This section compares wage dispersion and income inequality between union and nonunion workers for the entire sample and by gender and ethnic subsample. The results confirm much of the previous research on this issue in that wages in the union sector tend to be less dispersed and that income equality tends to be higher. Furthermore, indigenous people and women receive higher earnings in the union sector for a given set of characteristics.

20
The dispersion of log hourly wage in the union<sup>and nonunion sector in illustrated in</sup> Figure 2. The union dispersion curve lies to the right<sup>of the nonunion curve, reflecting the</sup> higher log hourly mean wage of 8.07 versus the nonunion<sup>log hourly wage mean of .'.76, a</sup> statistically significant difference. Furthermore, the union<sup>wage distribution is more peaked,</sup> revealing less dispersion than the distribution of nonunion<sup>wages. The difference between</sup> the standard deviation of the log hourly wage in the<sup>union sector (0.656) versus the nonunion</sup> standard deviation (0.78Z) is also statistically significant.

Figure 2: Distribution of Log Hourly Wages for Union<sup>and Nonunion Sectors</sup> <!-- Start of picture text --> Percent frequency<br>32<br>28 UnIon sarmple<br>24 Nonunlon sample<br>20 hourly elngs deviaton<br>16 Union 8.07 0.658<br>Nonunion 7.78 0.782<br>1 2<br>8<br>4<br>0<br>4 6 7 8 9 10 11<br>Log Hourly Wage<br><!-- End of picture text --> Though organized labor in Mexico may not command very<sup>large wage differentials, it</sup> has been effective in altering the wage structure,<sup>as evidenced by the earnings equations.</sup> With the reduced wage dispersion the concomitant effect of<sup>increases in wage equality among</sup> workers is observed. The Lorenz curve diagram (Figure<sup>3) illustrates substantial differences</sup> 21
in the Gini coefficients for both sectors. In the nonunion sector, the estimated Gini coefficient is 42.1, a lower value than typically observed in Latin America, largely due to the fully employed nature of the subsample (Psacharopoulos et al. 1993). In the union sector the Gini coefficient is greatly reduced to 33.5.

Figure 3: Lorenz Curves for Union **and** Nonunion Subsamples <!-- Start of picture text --> Cumulative Percent of Labor Eamings<br>100<br>G10 Coefficent<br>Union 33.80<br>80 Nonunion 42.12<br>60<br>40<br>Union subsomple<br>20 Nonunion subsomple<br>10 20 30 40 50 80 70 80 90 100<br>Population Share<br><!-- End of picture text -->

# _Wage Discrimination_

A number of studies of the union-nonunion wage differential have examined the potential mitigation of wage discrimination by organized labor. Though several studies have found union influence on ethnic wage discrimination, such studies have rarely found a sizable union impact on gender wage discrimination. A recent study in the United Kingdom and Lewis' (1986) review of wage differential literature in the United States both found the union 22
mark-up nearly the same for both men and women (Main and Reilly 1992; Lewis 1986). However, regarding ethnic wage discrimination, Lewis (1986) found strong evidence of a 0.05 to 0.10 wage gap difference between the total population and non-whites, indicating a larger union mark-up for non-whites. The benefits of umionization among indigenous people is observed in a recent study in Canada, where unionization was found to give indigenous workers a slight earnings advantage over non-Indians (Patrinos and Sakellariou 1992).

The examination of potential union mitigation of discrimination in this study finds that, unlike other studies based on developed nations, organized labor in Mexico plays a very strong role in reducing wage discrimination against employed women and indigenous people. The diminution of gender and ethnic discrimination is evidenced by the previously discussed differences in gender and ethnic variable parameters between the two full sample earnings equations in Table 3. Regarding gender, the difference in parameters between the union and nonunion sector reveals a negative marginal effect on the overall wage gap, indicating a greater union mark-up for women than for men. Analysis conducted on only the nonunion sector finds that 59.2 percent of the log hourly wage differential between men and working women is unexplained (controlling for endowment differences), whereas in the union sector, the log hourly earnings between genders is not statistically different.<sup>3</sup> This analysis serves as strong evidence of the reduction and possibly the elimination of gender wage discrimination by organized labor in Mexico.<sup>4</sup> 3 Results available from authors upon request.

4 Note that this analysis only compares the union wage differential among working women. The reduction in gender wage discrimination by unions for all women, employed and unemployed, once accounting for selectivity, may differ.

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Ethnicity plays a significant role in wage determination in the nonunion sector. The estimated _municipio_ indigenous percent variable coefficient of -0.8 indicates that for each percentage point increase in the probability of a sampled individual being indigenous, the expected wage drops by 0.8 percent. Thus, for someone living in a seventy percent indigenous _municipio_ his/her expected wage drops by a substantial 56 percent compared to someone living in a _municipio_ with no indigenous people. In contrast, in the union sector the probability of being indigenous is statistically nonsignificant with regard to wage determination. In addition, the difference in estimated parameters for _municipio_ indigenous percent reveals a greater union mark-up for those living in indigenous areas. Analysis conducted on only the nonunion sector finds 52.9 percent of the wage differential between those in less indigenous areas (less than 5 percent indigenous _municipios)_ and those in more indigenous areas (above 20 percent indigenous _municipios)_ can not be accounted for when controlling for endowment differences. Similar to differenaces in earnings by gender, in the union sector, the log hourly earnings between more and less indigenous areas is not statistically different. When compared to the aforementioned discrimination against indigenous people in the nonunion sector, the lack of statistical difference in earnings between indigenous and nonindigenous areas in the union sector serves as a strong indication that unions help to substantially reduce and possibly eliminate wage discrimination against indigenous people.

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# _Northern Border_

Nowhere do the relations between the United States and Mexico play a more significant role than they do in the border region between the two countries. The crossborder economic integration of this region proved a critical element in the debate over free trade. In the review of NAFTA, one of the most politically sensitive issues facing the United States and Mexico has been the labor issue. Much of the debate has been fueled by supposedly low Mexican wage rates, often a tenth of comparable wage rates in the United States, and the popular assertion that Mexican labor is reluctant to organize (Weintraub et al. 1991). Because of the increasing economic and political importance of the northern border, this section takes a closer look at this dynamic region.

Though overall wage rates in Mexico are considerably lower on average than wage rates m the United States, distinct regional variations in the wage rate in Mexico vary the degree of wage rate difference between the two nations. Analysis in regional wage variations in Mexico reveal that the northern border enjoys substantially greater wage rates than the rest of the country. Table 6 examines average hourly wages by region and union membership.

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# **Table 6: Union & Nonunion Hourly Wages** _(1989 pesos)_ **by Region**

||North|Region<br>Other|Total|
|---|---|---|---|
|Union|4,352|3,996_*_|4,065_*_|
|Nonunion|4,068 t|3,036|3,283|
|Total|4,137t|3,321|3,506|

Source: INEGI (1989) Notes: t indicates statistical different at the 99% level from 'other' region. * indicates statistical different at the 99% level from nonunion sector.

Hourly wages examined only by region show a considerable hourly wage advantage in the northern states, as previously noted (Table 3). Hourly wages examined only by union status, when not accouting for differences in worker quality, reveal a considerable wage advantage for union members. However, when hourly wages are examined by both union status and region, there is a revealing disparity. The mean hourly wage level in the northern region between the union and nonunion sector is only 6.98 percent, which, when controlled for endowment differences between the two sectors, amounts to the aforementioned -2.1 percent union wage gap. In the rest of the country, the mean wage rate difference between the two sectors is 31.6 percent or a much greater wage gap of 14.1 percent, when accounting for worker differences. This evidence seems to further substantiate the weaker position of unions in the northern region vis-i-vis the rest of the country. This assertion is further supported by the ob. erved -2.3 percent probability of union membership in northern states found in the above union status logit analysis. This evidence suggests that Mexican labor in the northern states is less likely to organize and when organized is weaker in comparison to organized labor in the rest of the country.

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To further examine the northern region, union and nonunion sector wage equations are estimated for only those observations in the northern states. Table 7 lists the two wage equations and the marginal contribution of various characteristics upon the overall wage gap. Examining the differences between the equations, it is interesting to note that in the union sector, with the exception of tertiary education, schooling makes no significant difference on hourly wage levels, indicative of the extent to which unions standardize rates of pay, reducing wage dispersion by permitting less individual variation in wages for workers. In the nonunion sector, the usual earnings-education profile is observed; that is, wages increase monotonically with education. Gender is nonsignificant in the union sector, and _municipio_ indigenous percentage is nonsignificant in both sectors, most probably due to the small indigenous presence in the northern region.

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Table 7: Union and Non-union Hourly Earnings Functions Northem States

||Sector|Marginal<br>Contribution|
|---|---|---|
|Variable|Union<br>Nonunion|:@"-r)|
|Education levela|||
|Primary|0.224<br>0.214t<br>(0.53)<br>(2.19)|0.004|
|Secondary Incomplete|0.465<br>0.584t<br>(1.09)<br>_(5.54)_|-0.039|
|Secondary Complete|0.703<br>0.901*<br>(1.64)<br>(7.88)|-0.027|
|Tertiary|1.080t<br>1.289t<br>(2.52)<br>(11.34)|0.032|
|Experience|0.053t<br>0.063t<br>(6.62)<br>(12.46)|-0.170|
|Experience squared|-0.0008<br>-0.001t<br>_(5.08)_<br>(10.58)|0.095|
|Male|0.088<br>0.151|-0.042|
||_(1.57)_<br>(3.86)||
|_Municipio_Indigenous Percent|0.017<br>-0.006|0.024|
||(1.23)<br>(0.96)||
|Industrial Sectorab|||
|Industrial Manufacturing|-0.0006<br>-0.196<br>(0.005)<br>(1.11)|0.054|
|Utilities|0.167<br>-0.527<br>(0.873)<br>(1.80)|0.007|
|Construction|0.191<br>-0.343|_0.051_|
||(1.04)<br>(1.89)||
|Commerce|-0.072<br>-0.217|0.024|
||(0.48)<br>(1.22)||
|Transportadon|0.484<br>-0.152|0.023|
||(3.17)<br>(0.75)||
|Fmancial Services|0.245<br>0.117|0.003|
||(1.33)<br>(0.56)||
|Services|0.312 t<br>-0.293|0.225|
||(2.58)<br>(1.67)||
|Constant|6.742<br>6.964|-0.222|
|Adjusted R<sup>2</sup>|0.292<br>0.214||
|N|541<br>1,652||
|Adjusted Wage Gap||-0.021|

# Source: INEGI (1989)

Notes: t significant at the 95% level. * signifcant at the 99% level. 'Residual is no education. "Residual sector is extraction. Numbers is parenthesis are t values. 0 is the estimated coefficient. u and n subscripts represent union and nonunion subsamnples, respectively. I is the fill sample weighted variable mean.

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The variables controlling for industrial sectors reveal some interesting differences between the union and nonunion sectors and the northern region and the rest of the country. In the nonunion sector there is no statistically significant difference in wage rates between industrial sectors, whereas in the union sector the transportation and service industry wage rates are significantly different from the omitted extraction sector. The greater inter-industry wage dispersion of the union sector compared to the nonunion sector observed in the northern region differs from the greater nonunion inter-industry wage dispersion commonly observed in empirical analysis, including the earlier full sample analysis in this study (see Table 3).

# Conclusions

The estimated union-nonunion wage gap, based on a subsample of 9,954 Mexican workers from a 1989 household survey, is about 10.4 percent. By international standards, specifically OECD countries, this is a low value and may suggest the relative weakness of organized labor in Mexico at the time of the survey. An exhaustive survey of the literature in the United States estimated an overall union-nonunion wage gap of around 14 percent over the period from 1967 to 1979. In none of the 12 years surveyed did the yearly average fall below 11 percent (Lewis 1986). A historical understanding of organized labor in Mexico supports the assertion that organized labor experienced difficult times in promoting the interests of its membership throughout most of the 1980s. However, the estimated 10.4 percent earnings advantage does indicate the existence of some bargaining strength, possibly 29
indicative of a recovery of organized labor's collective bargaining capacity, due in part to the improving economic situation of the country in the latter part of the decade.

The union wage gap varies considerably by personal, regional and sectoral characteristics. Personal characteristics, such as years of labor market experience, gender and ethnicity play an important role in determining the union-nonunion wage gap. Empirical analysis finds that workers with little or no work experience and workers with considerable work experience, women and indigenous people benefit to a greater extent in terms of hourly wages when employed in the union sector than when employed in the nonunion sector. Regional characteristics, most notably residence in northern states, are also important factors in wage gap determination. The northern region's estimated wage gap of -2.1 percent indicates a considerable diminution of union collective wage bargaining strength in this highly dynamic region, whereas the union wage gap in the rest of the country is estimated at a considerably higher 14.1 percent. Among industrial sectors, the variation in the wage gap is most pronounced in the services sector where a strong wage incentive exists in favor of union membership.

Organized labor in Mexico, as elsewhere, is found to have a strong influence in reducing wage dispersion. The concomitant of reduced wage dispersion - greater income equality, is also observed in the union sector where the estimated Gini coefficient is nearly 9 points below the nonunion sector's Gini coefficient, 33.5 versus 42.1.

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Organized labor has a very strong influence in reducing gender wage discrimination and wage discrimination against the indigenous population. This study finds significant indications of greater wage discrimination against women in the nonunion sector, whereas in :he union sector, average wage rates have no statistically significant difference between genders. The same is found true for native people. Where wage discrimination against native people is high in the nonunion sector, it is almost absent in the union sector, as evidenced by the lack of a significant statistical difference in hourly wages between indigenous and nonindigenous people.

This paper has attempted to measure the union-nonunion wage gap which should be differentiated from the more elusive (or more difficult to estimate) union wage gain. Where the union wage gap is essentially the difference in wages a worker would receive in the union sector versus the nonunion sector, the union wage gain is the difference in wages that would be observed in an economy in the presence of unions versus wages in the absence of unions. Therefore, though organized labor may at different times and in different regions not induce substantial wage gaps, it may have a substantial effect in ircreasing overall wage rates in general (both in the union and nonunion sector). This point is noted as a caveat in that the estimated wage gaps presented here should not be taken as the full measure of organized labor's effect on the Mexican wage structure, since the mere presence of unions can have a significant effect on wage rates and employment standards elsewhere in the economy.

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It should also be noted that though unions do increase income equality and reduce wage discrimination, this parity may be at the cost of factor efficiency and subject to specific definition of equity. If one deems a decrease in wage inequality to a minimum as equitable, then it can be strongly argued that unions enhance equity among fms and perhaps the economy as a whole. However, if one perceives equity as compensation based on merit and effort, than the union standardization of wages and strict seniority rules regarding wages and benefits may seem inequitable (Hirsch and Addison 1986). The stage of a country's political and economic development is likely to influence preferences and policy choices in this respect.

The debate over the effect of unions on the overall economic efficiency of a nation is ongoing. Whether organized labor is conducive to national growth and the success of adjustment programs forwarded by iurnational lenders, among others, has recently been addressed in an article by Freeman (1993), wherein he states, "Many economists see unions in developing countries as Peronist-style organizations that reduce efficiency at the enterprise level and produce populist inflationary macro-strategies. Some unions may fit this vision in some countries in some time periods; but the evidence of the late 1980's rejects it as a broad generalization" (Freeman, 1993: 404-405). He goes on further to add, "At the macro level, studies on the relation between unionism and adjustment in a variety of developing countries (Horton et al., 1991) have found that 'weakening of the unions...does not seem to be sufficient to ensure recovery', making it doubtful that 'launching into a wholescale advocacy of dismantling such institutions' is justifiable (see also Nelson, 1991)." (Freeman 1993: 405).

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Though studies have shown that while unions have modest wage effects<sup>and reduce the</sup> growth of employment, consistent with standard analysis, they are also associated<sup>with lower</sup> turnover, greater worker training, increased benefits and higher productivity (Standing<sup>1992).</sup> Surveying studies examining the net effect of unions on productivity, Sapsford<sup>and Tzannatos</sup> (1993) found that, though by no means unanimous, the weight of available evidence<sup>suggests</sup> that union workers are more productive than their nonunion counterparts in<sup>manufacturing.</sup> Moreover, the productivity differential between union and nonunion labor may<sup>be sufficiently</sup> large to offset the estimated union-nonunion wage differential (Ehrenberg<sup>and Smith 1991).</sup> Due to the fundamental importance of organized labor in national<sup>economies, potential</sup> democracies and the role of the civil society, a greater effort should<sup>be placed in the</sup> accumulation of relevant data in the future in order to fill the analytical<sup>gaps that exists</sup> concerning unions in the developing world. The results of this paper<sup>reveal that though</sup> organized labor does effect the national wage structure in much the same<sup>way it does in the</sup> developed world, differences do exist. In the case of Mexico, these differences<sup>serve as</sup> valuable insights into the functioning of the labor markets in the developing<sup>world.</sup> 33