Volume 9, Issue 1

This article is a video presentation of an interview with Buz Brock at the 12th SNDE conference in Atlanta Georgia on March 12, 2004. The interview includes 15 questions on topics ranging from nonlinear dynamics, ecological modeling, and heterogenous agents.

It is common in empirical macroeconomics to fit vector autoregressive (VAR) models to construct estimates of impulse responses. An important preliminary step in impulse response analysis is the selection of the VAR lag order. In this paper, we compare the six lag-order selection criteria most commonly used in applied work. Our metric is the mean-squared error (MSE) of the implied pointwise impulse response estimates normalized relative to their MSE based on knowing the true lag order. Based on our simulation design we conclude that for monthly VAR models, the Akaike Information Criterion (AIC) tends to produce the most accurate structural and semi-structural impulse response estimates for realistic sample sizes. For quarterly VAR models, the Hannan-Quinn Criterion (HQC) appears to be the most accurate criterion with the exception of sample sizes smaller than 120, for which the Schwarz Information Criterion (SIC) is more accurate. For persistence profiles based on quarterly vector error correction models with known cointegrating vector, our results suggest that the SIC is the most accurate criterion for all realistic sample sizes.

It is now widely recognized that the most commonly used efficient two-step GMM estimator may have large bias in small samples. In this paper we analyze by simulation the finite sample bias of two classes of alternative estimators. The first includes estimators which are asymptotically first-order equivalent to the GMM estimator, namely the continuous-updating, exponential tilting, and empirical likelihood estimators. Analytical and bootstrap bias-adjusted GMM estimators form the second class of alternatives. The Monte Carlo simulation study conducted in the paper for covariance structure models shows that all alternative estimators offer much reduced bias as compared to the GMM estimator, particularly the empirical likelihood and some of the bias-corrected GMM estimators.

We estimate a unit root bilinear process using the Maximum Likelihood method with log-likelihood function constructed by means of the Kalman filter, and evaluate the finite sample properties of this estimator.One hundred and five world-wide price series are tested for unit root bilinearity applying the test suggested by Charemza et al. (forthcoming). Applying the Maximum Likelihood estimator based on the Kalman filter, the null hypothesis of no bilinearity is rejected for 39 out of 105 series at the 5% level of significance. Most of the significant unit root bilinear coefficient estimates are explosive.

We analyze the transitional dynamics of an endogenous growth model with physical capital, human capital, and R&D. We provide conditions for the existence of a feasible steady state equilibrium with positive long-run growth. For appropriate parameter values, the transitional dynamics of the model is represented by a two-dimensional stable manifold. This provides much richer dynamics than that of the standard two-sector endogenous growth model which is characterized by a one-dimensional stable manifold. We also show how the adjustment paths can be correctly computed by noting that the continuity of the shadow prices involves the continuity of transitional paths.

Traders in commodity markets may have different time horizons. This paper uses a scale analysis to investigate heterogeneous trading in such markets. Estimates are presented for price correlations by scale and long memory in the volatility of commodity prices. Wavelet variance is estimated using non-decimated wavelet transforms. Wavelets have the potential to be a useful tool for scale analysis in economics.

This paper is devoted to the empirical analysis of the dynamic behaviour of the FF/DM parity during the September 1987-July 1993 period. By explicitly allowing the strength of adjustment to vary with the extent of equilibrium error, we successively perform parametric, semiparametric and nonparametric estimations of the functional form of the nonlinear error-correction term. On the basis of these econometric tools, we highlight a stronger correction of positive deviations of the parity from the level consistent with its macroeconomic fundamentals and a nonlinear reversion towards a set of equilibrium exchange rates. This asymmetric adjustment of deviations from equilibrium discloses a reluctance for the undervaluation of the FF over the period.

Recent empirical research on the New Keynesian Phillips Curve (NKPC) does not offer any supporting evidence for its benchmark version in which all firms are forward-looking. There is, however, empirical support for a modified, “hybrid”, NPKC, in which only a proportion of the firms that use a forward-looking rule to set prices.This paper estimates both the benchmark and the hybrid versions of the NKPC using Turkish data. In contrast with the previous applications on developed countries like the U.S. and several Euro area countries, we find empirical support for the benchmark NPKC. This support persists even after controlling for the weak identification problem which has been a serious concern in generalized method of moment estimation. Moreover, the hybrid NKPC is refuted by the data, i.e. the backward-looking behavior is found to be statistically insignificant.