A number of authors have attemted to test whether the U.S. economy is in a determinate or an indeterminate equilibrium. We argue that to answer this question, one must be impose a priori restrictions on lag length that cannot be tested. We provide examples of two economic models. Model 1...

This paper develops a model with multiple steady states (low tax and unemployment rate versus high tax and unemployment rate) in which equilibrium selection is not conditioned on a sunspot variable. Instead, large enough shocks initiate unavoidable transitions from one regime to the other. The...

We study identiÞcation in a class of three-equation monetary models. We argue that these models are typically not identiÞed. For any given exactly identiffed model, we provide an algorithm that generates a class of equivalent models that have the same reduced form. We use our algorithm to...

We determine optimal monetary policy under commitment in a forwardlooking New Keynesian model when nominal interest rates are bounded below by zero. The lower bound represents an occasionally binding constraint that causes the model and optimal policy to be nonlinear. A calibration to the U.S....

We determine optimal discretionary monetary policy in a New-Keynesian model when nominal interest rates are bounded below by zero. Nominal interest rates should be lowered faster in response to adverse shocks than in the case without bound. Such ‘preemptive easing’ is optimal because...

We show how to use a simple perturbation method to solve non-linear rational expectation models. Drawing from the applied mathematics literature we propose a method consisting of series expansions of the non-linear system around a known solution. The variables are represented in terms of their...

This paper investigates the impact on the network growth of the level of merchant discount, the level of Multilateral Interchange Fee (MIF), and the consumers' and the merchants' awareness of positive network effects. In an artificial market, in which issuers and acquirers belong to the same...

Phenomena such as the Great Moderation have increased the attention of macro-economists towards models where shock processes are not (log-)normal. This paper studies a class of discrete-time rational expectations models where the variance of exogenous innovations is subject to stochastic regime...