Abstract Diagnostic expectations constitute a realistic behavioural model of inference. This paper shows that this approach to expectation formation can be productively integrated into the New Keynesian framework. Diagnostic expectations generate endogenous extrapolation in general equilibrium. We show that diagnostic expectations generate extra amplification in the presence of nominal frictions; a fall in aggregate supply generates a Keynesian recession; fiscal policy is more effective at stimulating the economy. We perform Bayesian estimation of a rich medium-scale model that incorporates consensus forecast data. Our estimate of the diagnosticity parameter is in line with previous studies. Moreover, we find empirical evidence in favour of the diagnostic model. Diagnostic expectations offer new propagation mechanisms to explain fluctuations.

Abstract We document that the real effects of monetary shocks last for over a decade. Our approach relies on (1) identification of exogenous and non-systematic monetary shocks using the trilemma of international finance; (2) merged data from two new international historical cross-country databases; and (3) econometric methods robust to long-horizon inconsistent estimates. Notably, the capital stock and total factor productivity (TFP) exhibit greater hysteresis than labor. When we allow for asymmetry, we find these effects with tightening shocks, but not with loosening shocks. When extending the horizon of the responses reported in several recent studies that use alternative monetary shocks, we find similarly persistent real effects, thus supporting our main findings.