Further Evidence on PPP Adjustment Speeds: the Case of Effective Real Exchange Rates and the EMS*

Two different approaches intend to resolve the ‘puzzling’ slow convergence to purchasing power parity (PPP) reported in the literature [see Rogoff (1996) , Journal of Economic Literature, Vol. 34.] On the one hand, there are models that consider a non‐linear adjustment of real exchange rate to PPP induced by transaction costs. Such costs imply the presence of a certain transaction band where adjustment is too costly to be undertaken. On the other hand, there are models that relax the ‘classical’ PPP assumption of constant equilibrium real exchange rates. A prominent theory put together by Balassa (1964, Journal of Political Economy, Vol. 72) and Samuelson (1964 Review of Economics and Statistics, Vol. 46) , the BS effect, suggests that a non‐constant real exchange rate equilibrium is induced by different productivity growth rates between countries. This paper reconciles those two approaches by considering an exponential smooth transition‐in‐deviation non‐linear adjustment mechanism towards non‐constant equilibrium real exchange rates within the EMS (European Monetary System) and effective rates. The equilibrium is proxied, in a theoretically appealing manner, using deterministic trends and the relative price of non‐tradables to proxy for BS effects. The empirical results provide further support for the hypothesis that real exchange rates are well described by symmetric, nonlinear processes. Furthermore, the half‐life of shocks in such models is found to be dramatically shorter than that obtained in linear models.     

Penalized h-likelihood approach for variable selection in AFT random-effect models

Survival models allowing for random effects (e.g., frailty models) have been widely used for analyzing clustered time-to-event data. Accelerated failure time (AFT) models with random effects are useful alternatives to frailty models. Because survival times are directly modeled, interpretation of the fixed and random effects is straightforward. Moreover, the fixed effect estimates are robust against various violations of the assumed model. In this paper, we propose a penalized h-likelihood (HL) procedure for variable selection of fixed effects in the AFT random-effect models. For the purpose of variable selection, we consider three penalty functions, namely, least absolute shrinkage and selection operator (LASSO), smoothly clipped absolute deviation (SCAD), and HL. We demonstrate via simulation studies that the proposed variable selection procedure is robust against the misspecification of the assumed model. The proposed method is illustrated using data from a bladder cancer clinical trial.     

Nonlinear adjustment,purchasing power parity and the role of nominal exchange rates and prices

Although the literature on purchasing power parity (PPP) is rich in controversy, the relative contribution of prices and nominal exchange rates to real exchange rate movements which restore PPP disequilibria has rarely been put under any close scrutiny. This paper as a first step applies a cointegrated VAR framework to test for stationary real exchange rates and linear adjustments in prices and nominal exchange rates. As a second step, ESTR error correction models are fitted to test whether nonlinear error correctional behaviour characterizes the data. The results clearly indicate that the nominal exchange rate is responsible for the nonlinear mean reverting behaviour in real exchange rates and also mainly drives overall adjustment. Applying dynamic stochastic simulations based on the estimated models, this study also confirms recent results that the half-life times of real exchange rate shocks are significantly smaller than the consensus benchmark of 3–5 years.     

人民币汇率购买力平价问题的重新研究——基于结构突变检验与变结构协整的视角

本文应用LM结构突变检验以及Gregory-Hansen等变结构协整方法,对人民币汇率购买力平价问题进行了重新研究。研究发现样本期内人民币汇率发生了两次结构突变,第一次发生在2005年7月,第二次发生在2006年12月。LM检验显示,发生了结构突变的汇率数据生成过程仍为单位根过程,意味着某些经济冲击确实对数据生成过程(DGP)产生了实质影响。进一步对比研究发现,在未考虑结构突变情况下,样本期内购买力平价不成立;但在考虑结构突变情况下,两种变结构协整方法都支持购买力平价成立。     

Predictability of the U.S. Dollar Index using a U.S. export and import price index-based relative PPP model

We use U.S. export and import price indexes to construct a relative purchasing power parity-based model of the nominal U.S. Dollar Index. The model is successful in predicting the future direction of change in the U.S. Dollar Index over a six-month period up to 68% of the time. Finally, the model, in combination with a simple linear, recursive technique, is able to statistically significantly outperform the random walk in predicting the value of the U.S. Dollar Index at terms of less than four months for the period from 1996 to 2005. The paper provides important implications for investors who are interested in the direction of change in the Dollar’s value, forecasting the level of the U.S. Dollar Index, as well as the extent of over- and undervaluation of the U.S. Dollar, in general.     

Panel LM Unit‐root Tests with Level Shifts*

This paper proposes a new panel unit‐root test based on the Lagrangian multiplier (LM) principle. We show that the asymptotic distribution of the new panel LM test is not affected by the presence of structural shifts. This result holds under a mild condition that N/T→k, where k is any finite constant. Our simulation study shows that the panel LM unit‐root test is not only robust to the presence of structural shifts, but is more powerful than the popular Im, Pesaran and Shin (IPS) test. We apply our new test to the purchasing power parity (PPP) hypothesis and find strong evidence for PPP.     

Testing cointegration relationship in a semiparametric varying coefficient model

In this paper, we develop two cointegration tests for two varying coefficient cointegration regression models, respectively. Our test statistics are residual based. We derive the asymptotic distributions of test statistics under the null hypothesis of cointegration and show that they are consistent against the alternative hypotheses. We also propose a wild bootstrap procedure companioned with the continuous moving block bootstrap method proposed in  Paparoditis and Politis (2001) and  Phillips (2010) to rectify severe distortions found in simulations when the sample size is small. We apply the proposed test statistic to examine the purchasing power parity (PPP) hypothesis between the US and Canada. In contrast to the existing results from linear cointegration tests, our varying coefficient cointegration test does not reject that PPP holds between the US and Canada.     

Much Ado About Nothing: the Mixed Models Controversy Revisited

We consider a well-known controversy that stems from the use of two mixed models for the analysis of balanced experimental data with a fixed and a random factor. It essentially originates in the different statistics developed from such models for testing that the variance parameter associated to the random factor is null. The corresponding hypotheses are interpreted as that of null random factor main effects in the presence of interaction. The controversy is further complicated by different opinions regarding the appropriateness of such hypothesis. Assuming that this is a sensible option, we show that the standard test statistics obtained under both models are really directed at different hypotheses and conclude that the problem lies in the definition of the main effects and interactions. We use expected values as in the fixed effects case to resolve the controversy showing that under the most commonly used model, the test usually associated to the inexistence of the random factor main effects addresses a different hypothesis. We discuss the choice of models, and some further problems that occur in the presence of unbalanced data.     

Inference on stochastic time-varying coefficient models

Recently, there has been considerable work on stochastic time-varying coefficient models as vehicles for modelling structural change in the macroeconomy with a focus on the estimation of the unobserved paths of random coefficient processes. The dominant estimation methods, in this context, are based on various filters, such as the Kalman filter, that are applicable when the models are cast in state space representations. This paper introduces a new class of autoregressive bounded processes that decompose a time series into a persistent random attractor, a time varying autoregressive component, and martingale difference errors. The paper examines, rigorously, alternative kernel based, nonparametric estimation approaches for such models and derives their basic properties. These estimators have long been studied in the context of deterministic structural change, but their use in the presence of stochastic time variation is novel. The proposed inference methods have desirable properties such as consistency and asymptotic normality and allow a tractable studentization. In extensive Monte Carlo and empirical studies, we find that the methods exhibit very good small sample properties and can shed light on important empirical issues such as the evolution of inflation persistence and the purchasing power parity (PPP) hypothesis.     

A Simple Panel‐CADF Test for Unit Roots*

In this paper, we propose a simple extension to the panel case of the covariate‐augmented Dickey–Fuller (CADF) test for unit roots developed in Hansen (1995) . The panel test we propose is based on a P values combination approach that takes into account cross‐section dependence. We show that the test has good size properties and gives power gains with respect to other popular panel approaches. An empirical application is carried out for illustration purposes on international data to test the purchasing power parity (PPP) hypothesis.     

Purchasing power parity as a long-run relation

Dickey–Fuller and Stock–Watson tests of purchasing power parity (PPP) as a long-run proposition are provided within the cointegration framework proposed by Granger. Since different countries use different weights to construct price indices, the traditional constraint that the coefficients on the price indices should be unity in the log-linear PPP relation is relaxed. The absence of a general PPP relation cannot be rejected. At most, a PPP relation is indicated in five out of fifteen country pairs that are examined. Even if a long-run PPP relation exists, it is not found to be useful in predicting future nominal exchange rates, which is consistent with efficient speculative markets.     

进出口间接作用及其介体与路径——基于三时期参数变结构协整方法的研究

本文运用三时期参数变结构协整方法,着重研究我国进出口对经济增长的间接作用,以及产生间接作用的介体与路径。协整结果发现,大多数考察变量与进出口之间存在显著的参数变结构现象。实证研究得出,进出口通过投资、人力资本、技术进步、消费与经济结构这些介体对经济增长的间接作用有正有负,而加总效应都是正值,出口间接作用的弹性测算值较大,而进口间接作用的弹性测算值较小。     

中国劳务输出对进出口贸易影响的实证分析

本文采用修正的贸易引力模型,应用中国与175个国家(地区)1995~2004年的面板数据,就中国劳务输出对进出口贸易的影响进行实证分析。对样本总体的回归结果表明,我国对外劳务输出与出口之间存在互补关系,劳务输出能够带动出口增加;而劳务输出对进口没有明显影响,二者之间呈现不显著的替代关系。对样本国家(地区)按区域和收入分组的回归结果与对样本总体的回归结果基本一致:我国对大多数国家(地区)的劳务输出与出口之间存在正相关关系,特别是外派劳务最为集中的东亚和南亚,劳务输出对出口有着明显的拉动作用;在进口方面,除拉美和加勒比海国家外,对其余各组国家(地区)的劳务输出与进口之间均为负相关关系,而这种关系通常不显著。     

The impact of a Hausman pretest on the size of a hypothesis test: The panel data case

The size properties of a two-stage test in a panel data model are investigated where in the first stage a Hausman (1978) specification test is used as a pretest of the random effects specification and in the second stage, a simple hypothesis about a component of the parameter vector is tested, using a t$t$-statistic that is based on either the random effects or the fixed effects estimator depending on the outcome of the Hausman pretest. It is shown that the asymptotic size of the two-stage test equals 1 for empirically relevant specifications of the parameter space. The size distortion is caused mainly by the poor power properties of the pretest. Given these results, we recommend using a t$t$-statistic based on the fixed effects estimator instead of the two-stage procedure.     

A Skew‐normal copula‐driven GLMM

This paper presents a method for fitting a copula‐driven generalized linear mixed models. For added flexibility, the skew‐normal copula is adopted for fitting. The correlation matrix of the skew‐normal copula is used to capture the dependence structure within units, while the fixed and random effects coefficients are estimated through the mean of the copula. For estimation, a Monte Carlo expectation–maximization algorithm is developed. Simulations are shown alongside a real data example from the Framingham Heart Study.     

Empirical likelihood for high-dimensional linear regression models

High-dimensional data are becoming prevalent, and many new methodologies and accompanying theories for high-dimensional data analysis have emerged in response. Empirical likelihood, as a classical nonparametric method of statistical inference, has proved to possess many good features. In this paper, our focus is to investigate the asymptotic behavior of empirical likelihood for regression coefficients in high-dimensional linear models. We give regularity conditions under which the standard normal calibration of empirical likelihood is valid in high dimensions. Both random and fixed designs are considered. Simulation studies are conducted to check the finite sample performance.     

创新水平对电信设备企业出口影响的实证研究

本文使用中国电信设备企业的面板数据,首先运用固定效应模型与随机效应模型,实证检验了影响中国电信设备企业出口的因素。然后考虑到企业出口决定和出口量是两个相互联系的过程,我们采用Heckman两步选择模型进行估计发现:创新水平、人均工资、人均产出、以及宏观经济政策对中国电信设备企业的出口增加决定和出口增加都存在显著为正的影响。     

Nonlinear IV unit root tests in panels with cross-sectional dependency

We propose a unit root test for panels with cross-sectional dependency. We allow general dependency structure among the innovations that generate data for each of the cross-sectional units. Each unit may have different sample size, and therefore unbalanced panels are also permitted in our framework. Yet, the test is asymptotically normal, and does not require any tabulation of the critical values. Our test is based on nonlinear IV estimation of the usual augmented Dickey–Fuller type regression for each cross-sectional unit, using as instruments nonlinear transformations of the lagged levels. The actual test statistic is simply defined as a standardized sum of individual IV t-ratios. We show in the paper that such a standardized sum of individual IV t-ratios has limit normal distribution as long as the panels have large individual time series observations and are asymptotically balanced in a very weak sense. We may have the number of cross-sectional units arbitrarily small or large. In particular, the usual sequential asymptotics, upon which most of the available asymptotic theories for panel unit root models heavily rely, are not required. Finite sample performance of our test is examined via a set of simulations, and compared with those of other commonly used panel unit root tests. Our test generally performs better than the existing tests in terms of both finite sample sizes and powers. We apply our nonlinear IV method to test for the purchasing power parity hypothesis in panels.     

汽车制造企业采购管理中存在的问题及对策——以CA公司为例

以CA公司为例,从采购价格、生产计划调整、供应商选择、采购库存等方面分析了汽车制造企业采购管理过程中存在的一些问题,并针对这些问题提出了相应的对策,以期为汽车制造行业实施有效的采购管理提供参考。     

区域物流发展水平与进出口贸易关系的实证研究——基于河南省1978-2010年数据的协整分析和Granger因果检验

从供给和需求两个视角选取物流业发展水平的评价指标,对河南省物流业发展水平与进出口贸易增长关系进行了计量分析。通过Johansen协整检验得出:河南省物流业的供给和需求水平与进出口贸易之间存在长期稳定的协整关系;通过Granger因果检验得出:河南省物流业需求水平对进出口贸易有显著的影响,而物流业供给水平对进出口贸易影响不显著,物流业总体发展水平与进出口贸易之间未呈现良性互动态势。