“…Our estimation methodology builds on Lancaster's (1990, p. 118) formulation of a Wiener process duration model, but goes a step further by controlling for unobserved heterogeneity. Wiener process duration models are most common in the health literature, where time to death/admission/discharge is modeled as the first crossing of a barrier by a health process (e.g., Whitmore and Neufeldt, 1970, and Whitmore and Eaton, 1977, as cited by Seshadri, 1999, and Ting Lee, et al, 2000). Jovanovic (1984, 1979) models job turnover and employment transitions with a Wiener process model.…”