This paper proposes a model of the US unemployment rate which accounts for both its asymmetry and its long memory. Our approach, based on the tests of Robinson (1994), introduces fractional integration and nonlinearities simultaneously into the same framework (unlike earlier studies employing a...

"We propose and demonstrate a simple method for guiding researchers in developing quantitative models of economic fluctuations. We show that a large class of models are equivalent to a prototype growth model with time-varying wedges that resemble time-varying productivity, labor taxes, and...