"Empirical exercises in economics frequently involve estimation of highly nonlinear models. The criterion function may not be globally concave or convex and exhibit many local extrema. Choosing among these local extrema is non-trivial for a variety of reasons. In this paper, we analyze the...

In this paper, I examine the welfare consequences of conventional approximation methods in business cycle analysis: the log-linear approximation of model dynamics and the second-order approximation of social welfare. In a canonical New Keynesian model, the approximation around the deterministic...