Industry wage differentials, rent sharing and gender: three empirical essays

The first chapter is devoted to the analysis of the interaction between inter-industry wage differentials and the gender wage gap in six European countries, i.e. Belgium, Denmark, Ireland, Italy, Spain, and the U.K. To do so, we have relied on a unique harmonised matched employer-employee data set, the 1995 European Structure of Earnings Survey. As far as we know, this paper is the first to analyse with recent techniques, on a comparable basis, and from a European perspective: i) inter-industry wage differentials by gender, ii) gender wage gaps by industry, and iii) the contribution of industry effects to the overall gender wage gap. It is also one of the few, besides Kahn (1998), to analyse for both sexes the relationship between collective bargaining characteristics and the dispersion of industry wage differentials.

Empirical findings show that, in all countries and for both sexes, wage differentials exist between workers employed in different sectors, even when controlling for working conditions, individual and firm characteristics. We also find that the hierarchy of sectors in terms of wages is quite similar for male and female workers and across countries. Yet, the apparent similarity between male and female industry wage differentials is challenged by standard statistical tests. Indeed, simple t-tests show that between 43 and 71% of the industry wage disparities are significantly different for women and men. Moreover, Chow tests indicate that sectoral wage differentials are significantly different as a group for both sexes in all countries. Regarding the dispersion of the industry wage differentials, we find that results vary for men and women, although not systematically nor substantially. Yet, the dispersion of industry wage differentials fluctuates considerably across countries. It is quite large in Ireland, Italy and the U.K., and relatively moderate in Belgium, Denmark and Spain. For both sexes, results point to the existence of a negative and significant relationship between the degree of centralisation of collective bargaining and the dispersion of industry wage differentials.

Furthermore, independently of the country considered, results show that more than 80% of the gender wage gaps within industries are statistically significant. The average industry gender wage gap ranges between -.18 in the U.K. and -.11 in Belgium. This means that on average women have an inter-industry wage differential of between 18 and 11% below that for men. Yet, correlation coefficients between the industry gender wage gaps across countries are relatively small and often statistically insignificant. This finding suggests that industries with the highest and the lowest gender wage gaps vary substantially across Europe.

Finally, results indicate that the overall gender wage gap, measured as the difference between the mean log wages of male and female workers, fluctuates between .18 in Denmark and .39 in the U.K. In all countries a significant (at the .01 level) part of this gap can be explained by the segregation of women in lower paying industries. Yet, the relative contribution of this factor to the gender wage gap varies substantially among European countries. It is close to zero in Belgium and Denmark, between 7 and 8% in Ireland, Spain and the U.K., and around 16% in Italy. Differences in industry wage premia for male and female workers significantly (at the .05 level) affect the gender wage gap in Denmark and Ireland only. In these countries, gender differences in industry wage differentials account for respectively 14 and 20% of the gender wage gap. To sum up, findings show that combined industry effects explain around 29% of the gender wage gap in Ireland, respectively 14 and 16% in Denmark and Italy, around 7% in the U.K. and almost nothing in Belgium and Spain.

In conclusion, our results emphasize that the magnitude of the gender wage gap as well as its causes vary substantially among the European countries. This suggests that no single policy instrument will be sufficient to tackle gender pay inequalities in Europe. Our findings indicate that policies need to be tailored to the very specific context of the labour market in each country.

The second chapter examines investigates how rent sharing interacts with the gender wage gap in the Belgian private sector. Empirical findings show that individual gross hourly wages are significantly and positively related to firm profits-per-employee even when controlling for group effects in the residuals, individual and firm characteristics, industry wage differentials and endogeneity of profits. Our instrumented wage-profit elasticity is of the magnitude 0.06 and it is not significantly different for men and women. Of the overall gender wage gap (on average women earn 23.7% less than men), results show that around 14% can be explained by the fact that on average women are employed in firms where profits-per-employee are lower. Thus, findings suggest that a substantial part of the gender wage gap is attributable to the segregation of women is less profitable firms.

The third and final chapter contributes to the understanding of inter-industry wage differentials in Belgium, taking advantage of access to a unique matched employer-employee data set covering the period 1995-2002. Findings show the existence of large and persistent wage differentials among workers with the same observed characteristics and working conditions, employed in different sectors. The unobserved ability hypothesis may not be rejected on the basis of Martins’ (2004) methodology. However, its contribution to the observed industry wage differentials appears to be limited. Further results show that ceteris paribus workers earn significantly higher wages when employed in more profitable firms. The instrumented wage-profit elasticity stands at 0.063. This rent-sharing phenomenon accounts for a large fraction of the industry wage differentials. We find indeed that the magnitude, dispersion and significance of industry wage differentials decreases sharply when controlling for profits.