Testing the New Keynesian Phillips Curve through Vector Autoregressive models: Results from the Euro area.

In this paper we set out a test of the New Keynesian Phillips Curve (NKPC) based on Vector Autoregressive (VAR) models. The proposed technique does not rely on the Anderson and Moore (1985) method and can be implemented with any existing econometric software. The idea is to use a VAR involving the inflation rate and the forcing variable(s) as the expectation generating system and find the restrictions that nest the NKPC within the VAR. The model can be estimated and tested through maximum likelihood methods. We show that the presence of feedbacks from the inflation rate to the forcing variable(s) can affect solution properties of the NKPC; when feedbacks are detected the VAR should be regarded as the final form solution of a more general structural model. Possible non-stationary in the variables can be easily taken into account within our framework. Empirical results point that the standard "hybrid" versions of the NKPC are far from being a good first approximation to the dynamics of inflation in the Euro area

Present value relations, Granger non-causality and VAR stability

When in "exact" present value (PV) relations the decision variables do not Granger cause the explanatory variables and a VAR process is used to derive restrictions, the system embodies explosive roots. Hence any test of the PV restrictions would reject the null if the system incorporates Granger non-causality constraints. This paper investigates the issue.Granger non causality; Present value model; VAR

Estimation of quasi-rational DSGE monetary models

This paper proposes the estimation of small-scale dynamic stochastic general equilibrium (DSGE) monetary models under the quasi-rational expectations (QRE) hypothesis. The QRE-DSGE model is based on the idea that the determinate reduced form solution associated with the structural model, if it exists, must have the same lag structure as the ‘best fitting’ vector autoregressive (VAR) model for the observed time series. After discussing solution properties and the local identifiability of the model, a likelihood-based iterative algorithm for estimating the structural parameters and testing the data adequacy of the system is proposed. A Monte Carlo experiment shows that, even controlling for the omitted dynamics bias, the over-rejection of the nonlinear cross-equation restrictions when asymptotic critical values are used and variables are highly persistent is a relevant issue in finite samples. An application based on euro area data illustrates the advantages of using error-correcting formulations of the QRE-DSGE model when the inflation rate and the short-term interest rate are approximated as difference stationary processes. A parametric bootstrap version of the likelihood-ratio test for the implied cross-equation restrictions does not reject the estimated QRE-DSGE model.Dynamic stochastic general equilibrium model, Maximum Likelihood estimation, Quasi-Rational Expectations, VAR. Modelli DSGE, Stima di massima verosimiglianza, Aspettative Quasi-Razionali, Modelli VAR.

Testing the New Keynesian Phillips Curve through Vector Autoregressive models : Results from the Euro area.

In this paper we set out a test of the New Keynesian Phillips Curve (NKPC) based on Vector Autoregressive (VAR) models. The proposed technique does not rely on the Anderson and Moore (1985) method and can be implemented with any existing econometric software. The idea is to use a VAR involving the inflation rate and the forcing variable(s) as the expectation generating system and find the restrictions that nest the NKPC within the VAR. The model can be estimated and tested through maximum likelihood methods. We show that the presence of feedbacks from the inflation rate to the forcing variable(s) can a?ect solution properties of the NKPC; when feedbacks are detected the VAR should be regarded as the final form solution of a more general structural model. Possible non-stationary in the variables can be easily taken into account within our framework. Empirical results point that the standard “hybrid” versions of the NKPC are far from being a good first approximation to the dynamics of inflation in the Euro area.Inflation dynamics, New Keynesian Phillips Curve, Forwardlooking behavior, VEqCM.

Determinacy, indeterminacy and dynamic misspecification in linear rational expectations models

This paper proposes a testing strategy for the null hypothesis that a multivariate linear rational expectations (LRE) model has a unique stable solution (determinacy) against the alternative of multiple stable solutions (indeterminacy). Under a proper set of identification restrictions, determinacy is investigated by a misspecification-type approach in which the result of the overidentifying restrictions test obtained from the estimation of the LRE model through a version of generalized method of moments is combined with the result of a likelihood-based test for the cross-equation restrictions that the LRE places on its finite order reduced form under determinacy. This approach (i) circumvents the nonstandard inferential problem that a purely likelihood-based approach implies because of the presence of nuisance parameters that appear under the alternative but not under the null, (ii) does not involve inequality parametric restrictions and nonstandard asymptotic distributions, and (iii) gives rise to a joint test which is consistent against indeterminacy almost everywhere in the space of nuisance parameters, i.e. except for a point of zero measure which gives rise to minimum state variable solutions, and is also consistent against the dynamic misspecification of the LRE model. Monte Carlo simulations show that the testing strategy delivers reasonable size coverage and power in finite samples. An empirical illustration focuses on the determinacy/indeterminacy of a New Keynesian monetary business cycle model for the US.Determinatezza, Indeterminatezza, Massima verosimiglianza, Metodo generalizzato dei momenti, Modello lineare con aspettative, Identificazione, Variabili Strumentali, VAR,VARMA Determinacy, Generalized method of moments, Indeterminacy, LRE model, Identification, Instrumental Variables, Maximum Likelihood, VAR, VARMA

On the blow-up threshold for weakly coupled nonlinear Schroedinger equations

We study the Cauchy problem for a system of two coupled nonlinear focusing Schroedinger equations arising in nonlinear optics. We discuss when the solutions are global in time or blow-up in finite time. Some results, in dependence of the data of the problem, are proved; in particular we give a bound, depending on the coupling parameter, for the blow-up threshold.Comment: 14 page

Dispersive estimates for the Dirac equation in an Aharonov-Bohm field

We prove local smoothing and weighted Strichartz estimates for the Dirac equation with a Aharonov-Bohm potential. The proof relies on an explicit representation of the solution built in terms of spectral projections.Comment: 18 page