
on Econometric Time Series 
By:  Fabrizio Iacone (University of York); Stepana Lazarova (Queen Mary University of London) 
Abstract:  We consider changes in the degree of persistence of a process when the degree of persistence is characterized as the order of integration of a strongly dependent process. To avoid the risk of incorrectly specifing the data generating process we employ local Whittle estimates which uses only frequencies local at zero. The limit distribution of the test statistic under the null is not standard but it is well known in the literature. A Monte Carlo study shows that this inference procedure performs well in finite samples. 
Keywords:  Long memory, persistence, break, local Whittle estimate 
JEL:  C22 
Date:  2017–08–18 
URL:  http://d.repec.org/n?u=RePEc:qmw:qmwecw:830&r=ets 
By:  KANAZAWA, Nobuyuki 
Abstract:  I propose a flexible nonlinear method for studying the time series properties of macroeconomic variables. In particular, I focus on a class of Artificial Neural Networks (ANN) called the Radial Basis Functions (RBF). To assess the validity of the RBF approach in the macroeconomic time series analysis, I conduct a Monte Carlo experiment using the data generated from a nonlinear New Keynesian (NK) model. I find that the RBF estimator can uncover the structure of the nonlinear NK model from the simulated data whose length is as small as 300 periods. Finally, I apply the RBF estimator to the quarterly US data and show that the response of the macroeconomic variables to a positive supply shock exhibits a substantial time variation. In particular, the positive supply shocks are found to have significantly weaker expansionary effects during the zero lower bound periods as well as periods between 2003 and 2004. The finding is consistent with a basic NK model, which predicts that the higher real interest rate due to the monetary policy inaction weakens the effects of supply shocks. 
Keywords:  Neural Networks, Radial Basis Functions, Zero Lower Bound, Supply Shocks 
JEL:  C45 E31 
Date:  2018–03 
URL:  http://d.repec.org/n?u=RePEc:hit:hiasdp:hiase64&r=ets 
By:  Antonis Demos (www.aueb.gr/users/demos); Dimitra Kyriakopoulou 
Abstract:  We derive analytical expressions of bias approximations for maximum likelihood (ML) and quasimaximum likelihood (QML) estimators of the EGARCH(1; 1) parameters that enable us to correct after the bias of all estimators. The bias correction mechanism is constructed under the specification of two methods that are analytically described. We also evaluate the residual bootstrapped estimator as a measure of performance. Monte Carlo simulations indicate that, for given sets of parameters values, the bias corrections work satisfactory for all parameters. The proposed fullstep estimator performs better than the classical one and is also faster than the bootstrap. The results can be also used to formulate the approximate Edgeworth distribution of the estimators. 
Keywords:  Exponential GARCH, maximum likelihood estimation, finite sample properties, bias approximations, bias correction, Edgeworth expansion, bootstrap 
JEL:  C13 C22 
Date:  2018–02–23 
URL:  http://d.repec.org/n?u=RePEc:aue:wpaper:1802&r=ets 
By:  Antonis Demos (www.aueb.gr/users/demos); Dimitra Kyriakopoulou 
Date:  2018–02–23 
URL:  http://d.repec.org/n?u=RePEc:aue:wpaper:1803&r=ets 
By:  Antonis Demos (www.aueb.gr/users/demos); Dimitra Kyriakopoulou 
Date:  2018–02–23 
URL:  http://d.repec.org/n?u=RePEc:aue:wpaper:1804&r=ets 
By:  Yang Lu (Centre d'Economie de l'Université de Paris Nord (CEPN)); Christian Gourieroux (University of Toronto and Toulouse School of Economics) 
Abstract:  We introduce Negative Binomial Autoregressive (NBAR) processes for (univariate and bivariate) count time series. The univariate NBAR process is defined jointly with an underlying intensity process, which is autoregressive gamma. The resulting count process is Markov, with negative binomial conditional and marginal distributions. The process is then extended to the bivariate case with a Wishart autoregressive matrix intensity process. The NBAR processes are Compound Autoregressive, which allows for simple stationarity condition and quasiclosed form nonlinear forecasting formulas at any horizon, as well as a computationally tractable generalized method of moment estimator. The model is applied to a pairwise analysis of weekly occurrence counts of a contagious disease between the greater Paris region and other French regions. 
Keywords:  Compound Autoregressive, Poissongamma conjugacy 
JEL:  C32 
Date:  2018–03 
URL:  http://d.repec.org/n?u=RePEc:upn:wpaper:201801&r=ets 
By:  Federico A. Bugni; Joel L. Horowitz 
Abstract:  Economic data are often generated by stochastic processes that take place in continuous time, though observations may occur only at discrete times. For example, electricity and gas consumption take place in continuous time. Data generated by a continuous time stochastic process are called functional data. This paper is concerned with comparing two or more stochastic processes that generate functional data. The data may be produced by a randomized experiment in which there are multiple treatments. The paper presents a test of the hypothesis that the same stochastic process generates all the functional data. In contrast to existing methods, the test described here applies to both functional data and multiple treatments. The test is presented as a permutation test, which ensures that in a finite sample, the true and nominal probabilities of rejecting a correct null hypothesis are equal. The paper also presents the asymptotic distribution of the test statistic under alternative hypotheses. The results of Monte Carlo experiments and an application to an experiment on billing and pricing of natural gas illustrate the usefulness of the test. 
Date:  2018–03 
URL:  http://d.repec.org/n?u=RePEc:arx:papers:1803.00798&r=ets 
By:  Yeonwoo Rho; Xiaofeng Shao 
Abstract:  In unit root testing, a piecewise locally stationary process is adopted to accommodate nonstationary errors that can have both smooth and abrupt changes in second or higherorder properties. Under this framework, the limiting null distributions of the conventional unit root test statistics are derived and shown to contain a number of unknown parameters. To circumvent the difficulty of direct consistent estimation, we propose to use the dependent wild bootstrap to approximate the nonpivotal limiting null distributions and provide a rigorous theoretical justification for bootstrap consistency. The proposed method is compared through finite sample simulations with the recolored wild bootstrap procedure, which was developed for errors that follow a heteroscedastic linear process. Further, a combination of autoregressive sieve recoloring with the dependent wild bootstrap is shown to perform well. The validity of the dependent wild bootstrap in a nonstationary setting is demonstrated for the first time, showing the possibility of extensions to other inference problems associated with locally stationary processes. 
Date:  2018–02 
URL:  http://d.repec.org/n?u=RePEc:arx:papers:1802.05333&r=ets 
By:  Daniel Grabowski (University of Giessen); Anna StaszewskaBystrova (University of Lodz); Peter Winker (University of Giessen) 
Abstract:  This article investigates the construction of skewnessadjusted confidence intervals and joint confidence bands for impulse response functions from vector autoregressive models. Three different implementations of the skewness adjustment are investigated. The methods are based on a bootstrap algorithm that adjusts mean and skewness of the bootstrap distribution of the autoregressive coefficients before the impulse response functions are computed. Using extensive Monte Carlo simulations, the methods are shown to improve the coverage accuracy in small and medium sized samples and for unit root processes for both known and unknown lag orders. 
Keywords:  Bootstrap, confidence intervals, joint confidence bands, vector autoregression 
JEL:  C15 C32 
Date:  2018 
URL:  http://d.repec.org/n?u=RePEc:mar:magkse:201810&r=ets 
By:  Emilio Zanetti Chini (Department of Economics and Management, University of Pavia) 
Abstract:  The Generalized Smooth Transition AutoRegression (GSTAR) parametrizes the joint asymmetry in the duration and length of cycles in macroeconomic time series by using particular generalizations of the logistic function. The symmetric smooth transition and linear autoregressions are peculiar cases of the new parametrization. A test for the null hypothesis of dynamic symmetry is discussed. Two case studies indicate that dynamic asymmetry is a key feature of the U.S. economy. Our model beats its competitors in point forecasting, but this superiority becomes less evident in density forecasting and in uncertain forecasting environments. 
Keywords:  Density forecasts, Econometric modelling, Evaluating forecasts, Generalized logistic, Industrial production, Nonlinear time series, Point forecasts, Statistical tests, Unemployment. 
JEL:  C22 C51 C52 
Date:  2018–03 
URL:  http://d.repec.org/n?u=RePEc:pav:demwpp:demwp0156&r=ets 
By:  Meenagh, David (Cardiff Business School); Minford, Patrick (Cardiff Business School); Wickens, Michael (Cardiff Business School); Xu, Yongdeng (Cardiff Business School) 
Abstract:  Indirect inference testing can be carried out with a variety of auxiliary models. Asymptotically these different models make no difference. However, in small samples power can differ. We explore small sample power and estimation bias both with different variable combinations and models of description  Vector Auto Regressions, Impulse Response Functions or Moments (corresponding to the Simulated Methods of Moments)  in the auxiliary model. We find that VAR and IRF descriptors perform slightly better than Moments but that different three variable combinations make little difference. More than three variables raises power and lowers bias but reduces the chances of finding a tractable model that passes the test. 
Keywords:  Indirect Inference, DGSE model, Auxiliary Models, Simulated Moments Method, Impulse Response Functions, VAR, Moments, power, bias 
JEL:  C12 C32 C52 E1 
Date:  2018–03 
URL:  http://d.repec.org/n?u=RePEc:cdf:wpaper:2018/7&r=ets 
By:  Busch, Marie; Sibbertsen, Philipp 
Abstract:  Several modified estimation methods of the memory parameter have been introduced in the past years. They aim to decrease the upward bias of the memory parameter in cases of low frequency contaminations or an additive noise component, especially in situations with a shortmemory process being contaminated. In this paper, we provide an overview and compare the performance of nine semiparametric estimation methods. Among them are two standard methods, four modified approaches to account for low frequency contaminations and three procedures developed for perturbed fractional processes. We conduct an extensive Monte Carlo study for a variety of parameter constellations and several DGPs. Furthermore, an empirical application of the logabsolute return series of the S&P 500 shows that the estimation results combined with a longmemory test indicate a spurious longmemory process. 
Keywords:  Spurious Long Memory; Semiparametric estimation; Low frequency contamination; Pertubation;Monte Carlo simulation 
Date:  2018–03 
URL:  http://d.repec.org/n?u=RePEc:han:dpaper:dp628&r=ets 