We develop a dynamic model of transitions in and out of employment. A worker finds a job at an optimal stopping time, when a Brownian motion with drift hits a barrier. This implies that the duration of each worker's jobless spells has an inverse Gaussian distribution. We allow for arbitrary...

This paper argues that a broad class of search models cannot generate the observed business-cycle-frequency fluctuations in unemployment and job vacancies in response to shocks of a plausible magnitude. In the U.S., the vacancy-unemployment ratio is 20 times as volatile as average labor...

This paper accounts for the observed increase in unemployment duration relative to the unemployment rate in the U.S. over the past thirty years, typified by the record low level of short-term unemployment. We show that part of the increase is due to changes in how duration is measured, a...