مدل سه حالته جریان های کارگری در تعادل عمومی

We develop a simple model featuring search frictions and a nondegenerate labor supply decision along the extensive margin. The model is a standard version of the neoclassical growth model with indivisible labor and idiosyncratic productivity shocks and frictions characterized by employment loss and employment opportunity arrival shocks. We argue that it is able to account for the key features of observed labor market flows for reasonable parameter values. Persistent idiosyncratic productivity shocks play a key role in allowing the model to match the persistence of the employment and out of the labor force states found in individual labor market histories.

Analyses of aggregate employment are dominated by two frameworks. One is the frictionless version of the standard growth model with an endogenous labor leisure choice, as in Kydland and Prescott [31], but modified as in Hansen [24] to include the indivisible labor formulation of Rogerson [48]. The other is the class of matching models a la Diamond–Mortensen–Pissarides, as described in Pissarides [44]. Loosely speaking, the former can be viewed as a model of labor force participation, while the latter can be viewed as a model of unemployment conditional on a participation rate. Cross country data reveal that there are significant differences across countries along all three margins: employment, unemployment and nonparticipation. Moreover, it seems reasonable to think that participation rates, employment rates and unemployment rates are all jointly determined, in the sense that any policy that affects one margin is likely to affect both of the other two margins. This suggests that a comprehensive model of the aggregate labor market should explicitly incorporate all three labor market states.

We have built a model that features search frictions and a nondegenerate labor supply decision along the extensive margin. We argue that the steady state equilibrium of our model does a reasonable job of matching labor market flows between the three labor force states of employment, unemployment and out of the labor force as long as idiosyncratic shocks are reasonably persistent. Persistent idiosyncratic shocks play a key role in allowing the model to match the persistence of the employment and out of the labor force states found in individual labor market histories. Available evidence suggests that the two prime sources of these shocks — wage shocks and health status shocks — are both very persistent. It seems reasonable to posit that family shocks associated with family size and caring for elderly family members are also likely to be persistent. Whereas for some issues it may not be important to identify the exact shocks that individuals face, for some issues this may be important. Understanding how the model behaves in the presence of multiple shocks would also be of interest.