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 study a mixed hitting-time (MHT) model that specifies durations as the first time a Lévy process— a continuous-time process with stationary and independent increments— crosses a heterogeneous threshold. Such models are of substantial interest because they can be reduced from...

This paper examines the empirical analysis of treatment effects on duration outcomes from data that contain instrumental variation. We focus on social experiments in which an intention to treat is randomized and compliance may be imperfect. We distinguish between cases where the treatment starts...

This paper determines the structural shocks that shape a firm's first year by estimating a structural model of firm growth, learning, and survival using monthly sales histories from 305 Texas bars. We find that heterogeneity in firms' pre-entry scale decisions accounts for about 40% of their...

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.

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...