Shimer (2005a) claims that the Mortensen-Pissarides search model of unemployment lacks an ampiflication mechanism because it cannot generate the observed business cycle fluctuations in unemployment given labor productivity shocks of plausible magnitude. This paper argues that part of the problem...

This paper presents a measure of vacancy posting that captures the behavior of total --print and online-- help-wanted advertising. By modeling the share of online job advertising as the diffusion of a new technology --online job posting and job search-- I can combine information on both print...