Grayham E. Mizon

Exogeneity, cointegration, and economic policy analysis

This overview examines conditions for reliable economic policy analysis based on econometric models, focusing on the econometric concepts of exogeneity, cointegration, causality, and invariance. Weak, strong, and super exogeneity are discussed in general, and these concepts are then applied to the use of econometric models in policy analysis when the variables are cointegrated. Implications follow for model constancy, the Lucas critique, equation inversion, and impulse response analysis. A small money-demand model for the United Kingdom illustrates the main analytical points. This article then summarizes the other articles in this issues special section on exogeneity, cointegration, and economic policy analysis.

Empirical analysis of macroeconomic time series: VAR and structural models

VAR and structural econometric models have complementary roles in the modelling of macroeconomic time series. A constant parameter VAR, provided it is statistically well specified, constitutes a valid basis for testing hypotheses of dynamic specification, exogeneity, and a priori structure, thus facilitating model evaluation, as well as suggesting a potentially efficient model development strategy. Deterministic (e.g. trends and regime shifts) and stochastic (e.g. integrated variables) non-stationarities are analysable within this framework, and the Johansen maximum likelihood procedure for cointegrated systems is used in an analysis of the determination of earnings, prices, productivity, and unemployment in the U.K

A simple message for autocorrelation correctors: don't

A process for the production of 6-hydroxynicotinic acid from nicotinic acid by means of enzymatic hydroxylation in the presence of microorganisms of the genera Pseudomonas, Bacillus or Achromobacter. By maintaining a specific concentration range during the addition of nicotinic acid, the biomass formation can take place in the same process step as the product formation, without product losses occurring by further decomposition.

Cointegration and Error Correction Mechanisms

Starting from a multivariate Wold representation for N variables that are integrated of order 1, this paper shows that, given that the N variables have r cointegrating vectors, there is an equivalence between five alternative representations of the multivariate model: the autoregressive representation; the error-correction representation; the interim multiplier representation; the Bewley (1979) representation; and the common trend representation. Proof of the theorem uses a result based on the Smith-McMillan lemma for polynomial matrices. The paper concludes by commenting on the different representations. Copyright 1989 by Royal Economic Society.

Costs of inflation

We review theoretical and empirical analyses of the costs of inflation. Part 2 of the paper examines microeconomic models in which inflation is perfectly anticipated, and viewed as the only distortion in the economy or as one of many distortionary taxes, which may or may not be chosen optimally. Part 3 turns to stochastic models with a more macroeconomic orientation, in which inflation is imperfectly perceived, or where real costs of price adjustment cause agents not to adjust fully in the presence of inflation. Part 4 discusses empirical work, which largely focuses on the relationship between the level of inflation, its variability, its unpredictability, and variation in relative prices.

Exogeneity, causality, and co-breaking in economic policy analysis of a small econometric model of money in the UK

Since the objective of economic policy is to change target variables in the DGP, when economic policy analysis uses an econometric model, it is important that the model delivers reliable inferences about policy responses in the DGP. This requires that the model be congruent and encompassing, and hence exogeneity, causality, cointegration, co-breaking, and invariance all play major roles. We discuss these roles in linear cointegrated VARs, prior to illustrating their importance in a bivariate model of money and interest rates in the UK over the last century.

A note on the distribution of the least squares estimator of a random walk with drift

Abstract It is shown that the application of the result that the Dickey-Fuller ‘ T ’ obtained from a regression with an intercept is asymptotically normal if the DGP is a random walk with drift may be of little use in small samples unless the drift is enormous. In fact the Dickey-Fuller distribution may give a better approximation in many case.

Encompassing: Concepts and Implementation*

The encompassing principle has been carefully and precisely defined in various contexts, since its first appearance in the 1980s literature in numerous papers by Hendry, Mizon and Richard. Since then, several distinct notions of encompassing have been proposed and still coexist in the literature. We describe, illustrate and connect these notions in this paper. We start with the intuitive properties of exact encompassing between estimated models and compare it with its testable counterpart, approximate encompassing. We examine these notions and their main properties within static and dynamic, parametric and non-parametric, classical and Bayesian models and estimators. Encompassing or the lack of encompassing, is also studied via the concepts of parsimonious and partial encompassing. Pseudo-true values, which are central elements in measuring and testing approximate encompassing, are defined in line with the concept of specificity between models. We also examine the role played by the data generating process in the different approaches in the literature.

Modelling economies in transition: an introduction

This paper considers the implications of structural breaks, such as have occurred in many transition economies, for econometric modelling based on the multivariate cointegration paradigm. It outlines recent developments on the identification of linear cointegrated systems, discusses some practical problems, and presents an extension to non-linear systems. This is followed by a discussion of the impact of structural breaks on the identification and estimation of such systems. Finally, it relates these issues to the other papers in this volume.

Modelling Relative Price Variability and Aggregate Inflation in the United Kingdom

The relationship between relative price variability and aggregate inflation in the United Kingdom is used to illustrate a number of issues in econometric modeling methodology. The rigorous evaluation of models, especially testing for congruence and encompassing, is emphasized. The valuable role of recursive estimation methods in assessing model adequacy is demonstrated. Attention is drawn to the potential limitations of single-equation and univariate analysis of time-series data, and a recently proposed modeling strategy for analyzing nonstationary variables with cointegrating relationship, based on sequential reductions of a congruent VAR, is applied to a small system involving inflation and relative price variability. Copyright 1991 by The editors of the Scandinavian Journal of Economics.