Trade Union Concentration and the Determination of Wages: The Case of Teachers in England and Wales

Multi-unionism is a common feature of the industrial relations scene, yet to date there has been relatively little economic analysis of its effects, in particular on the outcome of wage negotiations. In this paper, we examine the impact of multi-unionism—specifically, the degree of union membership concentration—on the determination of the relative pay of a particular occupational group, namely that of schoolteachers in England and Wales. We measure teacher trade union concentration using the Herfindahl index of concentration, and find that, after controlling for other possible influences, changes in the value of this index have a positive impact on schoolteachers' relative pay. In addition, we find union membership concentration to be a better indicator of 'union pushfulness' effects in wage determination than the traditional measure, union density. These findings are potentially of wider significance for the analysis of wage determination in multi-union environments.