Wage dispersion and firm heterogeneity.

Summary This thesis is a contribution to the study of the possible links between wage dispersion and firm heterogeneity from a theoretical and empirical perspective. It is composed of five chapters. The first three chapters follow the framework of the employment research models developed by Burdett and Mortensen (1999), in which wage dispersion is endogenous, without the addition of other heterogeneity. The first chapter proposes two extensions to this model: on the one hand, it considers the possibility for firms to differentiate on their choice of capital, and on the other hand, it endogenizes the arrival rate of job offers to employees. The second chapter estimates the model developed in the first chapter for certain sectors and concludes that the heterogeneity generated by the theoretical model is insufficient, compared with the heterogeneity observed in the data. The third chapter extends the model constructed in chapter 1 to the possibility for firms to recruit part-time workers. Chapters 4 and 5 characterize the empirical differences in wage policies between firms using matched firm-employee data over 20 years. It highlights and characterizes the extreme heterogeneity of their practices. Chapter 5 examines in particular the link between wage dispersion and productivity, interpreted in relation to the organization of firms.