Unemployment and econometric learning

We apply well-known results of the econometric learning literature to the Mortensen-Pissarides real business cycle model. The unique rational expectations equilibrium (REE) is always expectationally stable with decreasing gain learning, and this result is robust to over-parametrisation of the econometric model relative to the minimum state variable form used by agents. And so, from this perspective, the assumption of rational expectations in the model is not unreasonable. However, using a parametrisation with UK data, simulations suggest that the implied rate of convergence to the REE with least squares learning is slow. The cyclical response of unemployment to structural shocks is muted under learning, and a parametrisation which guarantees root-t convergence is generally not consistent with attempts to match the observed volatility of labour market data using the standard model.