"Shimer's calibrated version of the Mortensen-Pissarides model generates unemployment fluctuates much smaller than the data. Hagedorn and Manovskii present an alternative calibration that yields fluctuations consistent with the data, but this has been challenged by Costain and Reiter, who say it...

"The generation and implementation of ideas, or knowledge, is crucial for economic performance. We study this process in a model of endogenous growth with frictions. Productivity increases with knowledge, which advances via innovation, and with the exchange of ideas from those who generate them...