Sources of the Union Wage Gap: Results from High-Dimensional Fixed Effects Regression Models

41 Pages Posted: 4 Sep 2015

See all articles by John T. Addison

John T. Addison

University of South Carolina - Moore School of Business - Department of Economics; IZA Institute of Labor Economics

Pedro Portugal

Bank of Portugal - Research Department; New University of Lisbon; IZA Institute of Labor Economics

Hugo Vilares

Bank of Portugal

Abstract

This paper provides estimates of the union wage gap in Portugal, a nation until recently lacking independent data on union density at firm level. Having estimated nonlinear and linear estimates of the effect of union density on the wage gap, the next stage of the analysis seeks to account for the influence of worker, firm, and job-title permanent heterogeneity, using a three high dimensional fixed effects strategy. Gelbach's decomposition is used to determine the role of each as sources of the union wage gap. A generalization of this technique is applied for the nonlinear case. We find evidence of a substantial union wage gap in circumstances where the majority of the workforce is organized. There is also some clear indication of substitution effects among different types of compensation that favor of wage supplements (likely reflecting tax considerations) as bargaining power increases.The principal result of the decomposition exercise at the most aggregate level is that the union wage gap is mainly manifested through a firm fixed effect, suggesting that unions may force firms to reposition themselves as far as their wage compensation policies are concerned. A subsidiary result is that matching plays almost no role. More importantly, however, are the results obtained when a distinction is drawn between the (estimated) bargained wage and total earnings. Rising union density has a much greater influence upon the former and is negatively related to the difference between the two. This result is consistent with a wider literature indicating that firms have a 'wage cushion' enabling them to avoid some of the strictures of unionism bargaining power.

Keywords: union density, union wage gap, total compensation, bargained wages, wage cushion, wage supplements, worker/firm/job title fixed effects, Gelbach decomposition

JEL Classification: J31, J33, J41, J51, J52

Suggested Citation

Addison, John T. and Portugal, Pedro and Vilares, Hugo, Sources of the Union Wage Gap: Results from High-Dimensional Fixed Effects Regression Models. IZA Discussion Paper No. 9221. Available at SSRN: https://ssrn.com/abstract=2655242

John T. Addison (Contact Author)

University of South Carolina - Moore School of Business - Department of Economics ( email )

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HOME PAGE: http://mooreschool.sc.edu/moore/economics/profiles/addison.htm

IZA Institute of Labor Economics

P.O. Box 7240
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Germany

Pedro Portugal

Bank of Portugal - Research Department ( email )

Av. Almirante Reis 71, 6th
Lisbon 1150-012
Portugal
+351 21 313 0000 (Phone)
+351 21 814 3841 (Fax)

New University of Lisbon

Lisbon, 1099-085
Portugal

IZA Institute of Labor Economics

P.O. Box 7240
Bonn, D-53072
Germany

Hugo Vilares

Bank of Portugal ( email )

Rua Francisco Ribeiro, 2
Lisbon, 1150-165
Portugal

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