Relationship networks in the labor market: economic efficiency, social disparities, and wage inequality.

Summary In this thesis we study the impact of relationship networks on labor market efficiency and wage inequality. We consider, in a first part, the choice of agents between different search methods. We highlight the substitution effects between methods, which are possible and original sources of inefficiency. In this context, the impact of certain economic policies may be unexpected. On the one hand, sufficiently generous unemployment benefits can improve market efficiency by coordinating firms and workers on the most efficient methods. On the other hand, a policy aiming at increasing the "social capital" of the most disadvantaged populations may induce a substitution between methods, leading to an increase in the unemployment rate and a decrease in workers' welfare. In a second part, we study the effect of networks on wage inequalities. We first show that, even in a setting where all agents have the same productivity, networks can induce significant wage inequalities. Indeed, the wage received by a worker depends on the employment rate of his or her network, which defines his or her external opportunities. Since employment rates differ endogenously between networks, the latter generate wage dispersion in equilibrium. Finally, we propose a structural model of job search, taking into account the possible effect of networks on match quality. We estimate this model on French data and reject the idea that networks would allow more productive matches.