We assess whether "undue optimism" (Pigou) contributes to business cycle fluctuations. In our analysis, optimism (or pessimism) pertains to total factor productivity which determines economic activity in the long run. Optimism shocks are perceived changes in productivity which do not actually...

We present a sticky-price model incorporating heterogeneous firms and systematic firm-level productivity trends. Aggregating the model in closed form, we show that it delivers radically different predictions for the optimal inflation rate than canonical sticky price models featuring homogenous...