In the past decades several features of U.S. unemployment dynamics have been investigated empirically. The original focus of research was on the duration of unemployment. In later studies the cyclicality of incidence and duration, compositional effects and duration dependence of the exit rate...

In a large class of hazard models with proportional unobserved heterogeneity, the distribution of the heterogeneity among survivors converges to a gamma distribution. This convergence is often rapid. We derive this result as a general result for exponential mixtures and explore its implications...

We prove identification of dependent competing risks models in which each risk has a mixed proportional hazard specification with regressors, and the risks are dependent by way of the unobserved heterogeneity, or frailty, components. We show that the conditions for non-parametric identification...

This discussion paper has resulted in chapter 2 in: 'Losing Work, Moving On: International Perspectives On Worker Displacement', Peter J. Kuhn, Ed., 2002, W.E. Upjohn Institute for Employment Research, Kalamazoo, MI, ISBN 0-88099-234-4.

In their IZA Discussion Paper 10247, Johansson and Lee claim that the main result (Proposition 3) in Abbring and Van den Berg (2003b) does not hold. We show that their claim is incorrect. At a certain point within their line of reasoning, they make a rather basic error while transforming one...

In a large class of hazard models with proportional unobserved heterogeneity, the distribution of the heterogeneity among survivors converges to a gamma distribution. This convergence is often rapid. We derive this result as a general result for exponential mixtures and explore its implications...

Often, a treatment and the outcome of interest are characterized by the moment they occur, and these moments are realizations of stochastic processes with dependent unobserved determinants. We develop a simple and intuitive method for inference on the treatment effect. The method can be...