Discusses the process that matches unemployed workers to available job vacancies. Explores the microfoundations, empirical evidence, and estimation issues underlying the aggregate matching function.

The assumption of aggregate matching functions in labor markets is tested using a network configuration model for directed multigraphs. We use employer-employee matched records of the universe of employees and firms in Finland and find that aggregate matching functions, even at the level of submarkets, cannot explain the vast majority of the observed patterns of labor flows between firms. Our findings suggest the need for theoretical frameworks that take into account the structure of labor market frictions.

The aggregate matching (hiring) function relates gross hires to labor market tightness. Decompositions of aggregate hires show how the hiring process differs across different groups of workers and of firms. Decompositions include employment status in the previous month, age, gender and education. Another separates hiring between part-time and full-time jobs, which show different patterns in the current recovery. Shift-share analyses are done based on industry, firm size and occupation to show what part of the residual of the aggregate hiring function can be explained by the composition of vacancies. The hiring process appears to shift as a recovery starts, coinciding with shifts in the Beveridge curve. The paper also discusses some issues in the modeling of the labor market. Keywords: Trade, International Conflicts, War, Exhaustible Resources.