PPP: <Emphasis Type="Italic">Delusion</Emphasis> or <Emphasis Type="Italic">Reality</Emphasis>? Evidence from a Nonlinear Analysis

In this paper we analyze the validity of the purchasing power parity (PPP) in a nonlinear framework using data for 18 bilateral US dollar exchange rates. Following Enders and Ludlow (2002), we use unit root and cointegration tests that do not assume a specific nonlinear adjustment. We find evidence of non-linear mean reversion in deviations from the PPP equilibrium in 11 out of 18 currencies. Additionally, to disentangle the respective contribution of exchange rate and prices to the adjustment toward the long run equilibrium, we estimate a Vector Error Correction Model. According to our empirical analysis, there exists a nonlinear mechanism to correct for deviation from the PPP equilibrium that comes mainly from the exchange rates. This is consistent with theoretical arguments on international goods markets under transaction costs as well as with an emerging strand of empirical literature. These results highlight the importance of neglecting the possibility of nonlinearity in the debate about the PPP and provide empirical evidence that supports the scenario of the PPP hypothesis as a reality.     

Price Indices and Nonlinear Mean-Reversion of Real Exchange Rates

The purpose of this article is to apply a symmetric band-threshold autoregressive model to investigate several interesting issues regarding purchasing power parity (PPP). We find that the nonlinear adjustment toward PPP is sensitive to price indices and is supported if a traded-goods real exchange rate is applied. Moreover, we also uncover the sources of the real exchange rate adjustments toward PPP. Finally, our evidence points out that the estimated half-life with a large shock, based on a generalized impulse response function, can be explained by nominal rigidities.     

DO AFRICAN COUNTRIES MOVE ASYMMETRICALLY TOWARDS PURCHASING POWER PARITY?

This paper investigates the possibility that the adjustment towards long‐run relative purchasing power parity (PPP) is dependent upon the nature of deviations from PPP that are experienced. While existing studies involving developed and less developed countries often find against PPP having employed linear tests of non‐stationarity or non‐cointegration, we employ a new cointegration test, recently advocated by Enders and Siklos and Enders and Dibooglu, that tests for an asymmetric adjustment towards parity with respect to positive and negative deviations of the real exchange rate from its equilibrium value. Using a sample often African economies with data taken from the post‐Bretton Woods floating exchange rate era, long‐run PPP holds in eight of these cases if an explicit distinction is made between positive and negative deviations. Across the sample, we find variation in the type of asymmetry experienced and the roles played by price and nominal exchange rate adjustment.     

PURCHASING POWER PARITY WITH RANK TESTS FOR NONLINEAR COINTEGRATION IN AFRICAN COUNTRIES

This study applies nonlinear cointegration to assess exchange rates with the corresponding relative prices and aggregate price levels for 20 African countries. We find that a nonparametric rank test has higher power than parametric testing procedures; a true data‐generating process of exchange rate is in fact a stationary nonlinear process. We examine the validity of purchasing power parity (PPP) from the nonparametric nonlinear point of view and provide robust evidence that clearly indicates PPP holds true for these countries. Hence, the long‐run African countries exchange rate adjustments are in equilibrium with the relevant fundamentals as suggested by the PPP hypothesis in a nonlinear way.     

Do Real Exchange Rates Follow a Nonlinear Mean Reverting Process in Developing Countries?

In an effort to fight relatively high inflation, many developing countries try to manage their nominal exchange rates through official intervention. In addition, developing countries tend to have high transportation costs, tariffs, and nontariff barriers. These factors are among the sources of generating nonlinearity in real exchange rates and hence some nonlinear adjustment toward purchasing power parity (PPP) in developing countries. In this paper, we employ monthly real effective exchange rate (REER) data of 88 developing countries and test the null of nonstationarity versus an alternative of linear stationarity by the means of a conventional unit root test and compare the results with those obtained from a new test in which the null is the same but the alternative hypothesis is nonlinear stationarity. The latter test supports the PPP theory in more developing countries compared with the former test, suggesting that nonlinear adjustment toward PPP in developing countries is an important phenomenon. Reported country characterizations indicate that reversion in REER occurs more often for high-inflation countries and for countries with high flexibility in their exchange rates.     

Is reversion to PPP in euro exchange rates non-linear?

The paper tests for nonlinearities in the adjustment of the euro exchange rate towards purchasing power parity (PPP). It presents new survey based evidence consistent with non-linear patterns in euro exchange rate dynamics. Moreover, based on an exponential smooth transition autoregressive (ESTAR-) model, it finds strong evidence that the speed of mean reversion in euro exchange rates increases non-linearly with the magnitude of the PPP deviation. Accordingly, while the euro real exchange rate can be well approximated by a random walk if PPP deviations are small, in periods of significant deviations, gravitational forces are set to take root and bring the exchange rate back towards its long-term trend. Deviations from the PPP equilibrium for the euro-dollar rate need to be stronger in order to reach the same adjustment intensity as for other rates.

Real Exchange Rate Forecasting and PPP: This Time the Random Walk Loses

This paper brings four new insights into the Purchasing Power Parity (PPP) debate. First, we show that a half-life PPP (HL) model is able to forecast real exchange rates better than the random walk (RW) model at both short and long-term horizons. Second, we find that this result holds if the speed of adjustment to the sample mean is calibrated at reasonable values rather than estimated. Third, we find that it is preferable to calibrate, rather than to elicit as a prior, the parameter determining the speed of adjustment to PPP. Fourth, for most currencies in our sample, the HL model outperforms the RW also in terms of nominal exchange rate forecasting.     

汇率调整无效力问题的微观与宏观研究范式评析——关于20世纪80年代以来汇率理论研究的变迁原因与发展特征分析

由"购买力平价悖论"、"汇率不相关悖论"以及"汇率不完全转移"现象所代表的汇率调整无效力问题,是20世纪80年代以来国际经济学界最为关注的问题。经济学家应用静态局部均衡分析与动态一般均衡分析对这一问题的发生机制与实践影响进行了理论与经验的解释,这些研究重塑与发展了现代汇率理论。本文的目的在于评价这些汇率理论的变迁原因与发展特征,即在阐明传统汇率理论的现实挑战——西方经济在微观-产业层次与宏观-国际层次上遭遇的汇率调整无效力的典型事实的基础上,论述与评价经济学家运用静态局部均衡分析与动态一般均衡分析在解决汇率调整无效力问题的过程中取得的标志性的方法论贡献。     

Purchasing Power Parity: Error Correction Models and Structural Breaks

This paper examines purchasing power parity (PPP) behavior using error correction models (ECM) and allowing for structural breaks. We distinguish four different objectives: first, this paper examines which variable or variables (the exchange rate and/or international relative prices) exhibit a significant error correction mechanism. Second, this paper presents empirical evidence about the adjustment velocity to the long-run equilibrium. Third, it examines the evidence regarding cointegration and the adjustment coefficients parameter instability, and finally, it analyzes whether traded and non-traded sectors exhibit different behavior. The most important results are: (1) the predominant adjustment is in the exchange rate with a larger velocity adjustment than in relative prices; (2) the evidence suggests that when there are strong depreciations or appreciations in the exchange rate, the international relative prices adjust (i.e., there is evidence of pass-through); (3) the dynamic adjustment to equilibrium is, in general, stable.     

Long-Run Purchasing Power Parity with Asymmetric Adjustment

Tests of purchasing power parity (PPP) that use panel data are more supportive of the theory than are bilateral tests. The article uses threshold cointegration to explore long-run PPP. Using data from the post-Bretton Woods period, we show that cointegration with threshold adjustment holds for a number of European countries on a bilateral basis. Focusing on France and Germany as base countries, we show that the error-correction model has important nonlinear characteristics in that prices and the exchange rate have markedly different adjustment patterns for positive gaps from PPP than negative gaps.     

Food prices and long-run purchasing power parity in Africa

The purchasing power parity (PPP) theory is a cornerstone of exchange rate models in international economics. PPP is very important for two main reasons: first, it can serve as a prediction model for exchange rates, and second, it can serve as a benchmark in judging the level of exchange rate movements. This article utilised the Johansen cointegration technique in examining whether or not there is empirical support for long-run PPP in Africa. Annual data were used for exchange rates and food price indices in 25 countries covering the 1958-97 period. The empirical evidence showed strong support for long-run PPP in Africa, thereby providing wider acceptance for the applicability of PPP in exchange rate and other macroeconomic adjustment policies.     

Nonstationarity of Real Exchange Rates in the G7 Countries: Are They Cointegrated with Real Variables?

Using monthly data for the G7 countries in the post-Bretton Woods floating rate period, this paper demonstrates that almost all bilateral real exchange rates have unit roots and, hence, are nonstationary. Consequently, it rejects simple PPP as a long-run relationship. The paper also shows that many of these real exchange rates are cointegrated with other real economic variables such as relative labor productivity, terms-of-trade ratios, real trade balance ratios, and long-term real interest rate differentials. In particular, relative labor productivity is statistically significant with the correct sign for more than half of the country pairs for which cointegration is confirmed. This finding lends support to the Balassa–Samuelson productivity-bias hypothesis. These results imply that nonstationarity of real exchange rates and the consequent rejection of simple PPP can be consistent with the notion that real exchange rates revert to an equilibrium in the long run without deviating arbitrarily far from this equilibrium position.J. Japan. Int. Econ.,December 1997, pp. 523–547. Institute of Social Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan, and Faculty of Business and Commerce, Meiji University, 1-1 Kanda, Surugadai, Chiyada-ku, Tokyo 101, Japan.     

实际汇率与居民消费风险分担的动态关系——基于预期的视角

通过考虑居民预期行为的作用，实际汇率与居民消费风险分担的动态关系是一个附带预期的渐进调整过程。在利用东亚9个主要经济体的数据对该关系进行研究后发现：（1）东亚各国居民之间的消费风险分担程度较低，但是从2000年之后，居民消费风险分担程度在逐渐提高；（2）实际汇率变动基本上没有平滑东亚各国（地区）居民的消费变动；（3）持有静态预期行为的居民朝向长期消费风险分担均衡的调整程度较小，并且该调整速度较慢，同时持有理性预期行为的居民、持有适应性预期行为的居民背离长期消费风险分担均衡的调整程度较大，并且该调整速度较快，这是造成非完全消费风险分担均衡的重要原因。     

SHORT‐RUN AND LONG‐RUN DETERMINANTS OF THE REAL EXCHANGE RATE IN MEXICO

This paper explores the real exchange rate behavior in Mexico from 1960 until 2005. Since the empirical analysis reveals that the real exchange rate is not mean reverting, we propose that economic fundamental variables affect its evolution in the long run. Therefore, based on equilibrium exchange rate paradigms, we propose a simple model of real exchange rate determination, which includes the relative GDP per capita, the real interest rates, and the net foreign assets over a long period of time. Our analysis also considers the dynamic adjustment in response to shocks through impulse response functions derived from the multivariate vector autoregressive (VAR) model.     

Assessing convergence to purchasing power parity: A panel study for ten OECD countries

Assessing Convergence to Purchasing Power Parity: A Panel Study for 10 OECD Countries. — The paper analyzes whether post-Bretton Woods real exchange rates of ten OECD countries are nonstationary so that long-run purchasing power parity (PPP) can be considered to hold. A test procedure is proposed which treats the various real exchange rates as a panel but still allows to assess the rate of convergence to PPP for each pair of currencies separately. It is shown that long-run (tradables-) PPP holds between all countries analyzed. Rates of convergence to PPP, however, are found to be quite different across countries. For most of the OECD countries convergence takes place faster than previously indicated.     

Cointegration Tests of Purchasing Power Parity: the Case of the Thai Baht*

This paper will examine the validity of the purchasing power parity (PPP) hypothesis for the Thai baht vis-à-vis the currencies of Thailand's key trading partners under the new exchange rate regime using the cointegration technique. The major conclusions obtained from this empirical analysis may be broadly summarized as follows. First, the empirical evidence, based on the DF and ADF statistics, seems to suggest that the nominal exchange rates and relative prices are well characterized as non-stationary I(1) processes. Second, the cointegration analysis provides no evidence in support of a long-run equilibrium relationship between bilateral nominal exchange rates for the Thai baht vis-à-vis the currencies of Thailand's major trading partners and the corresponding relative price ratios. This implies rejection of PPP for these countries. If this is the case, considerable care should be taken in assessing the long-run implications for the real exchange rate, and thus competitiveness against Thailand's key trading partners, of shocks to the nominal exchange rate.     

人民币实际有效汇率变动的中国产业结构升级效应

本文在劳动力市场动态均衡模型的基础上,通过构建厂商利润最大化模型,验证了汇率变动影响产业结构调整的传导机制;然后通过协整检验、误差修正模型检验和脉冲响应分析进一步对传导机制进行验证,并具体考察了1981～2010年度人民币实际有效汇率变动对中国产业结构调整的影响。研究结果表明:人民币实际有效汇率变动能够通过价格水平、对外贸易(出口和进口)和FDI 3条路径影响中国的产业结构调整。其中,价格水平和进口是两条重要路径,FDI的影响作用并不显著。人民币实际有效汇率升值能够促进中国产业结构的优化升级。     

Purchasing Power Parity before and after the Adoption of the Euro

This paper examines the purchasing power parity (PPP) hypothesis for the post–Bretton Woods era including the period after the introduction of the euro. The study applies a new nonlinear unit root test to the bilateral real exchange rates (RERs) of both European and other industrial countries with the French franc and German mark (and the euro after 1998), as well as the US dollar as numeraire currencies. The results of the study provide stronger support for PPP than any earlier studies of bilateral PPP for industrial countries and suggest that (1) PPP tends to hold well within the European Union (EU) even before the adoption of the euro, (2) the evidence for PPP becomes more significant for both EU and non-EU countries when the sample period is extended to the euro era, and (3) convergence toward PPP between the EU countries, especially between the euro-area countries, tends to be nonlinear, while it is likely to be linear for the non-EU industrial countries. JEL no. F31, F33, G15, C22     

Decline in the persistence of real exchange rates,but not sufficient for purchasing power parity

The paper investigates the possibility of decline in the persistence of real exchange rates, or deviations from PPP. To this end, we test the null hypothesis of no decline in the PPP deviation persistence between two subsamples using a fractional integration framework. The test rejects the null at the 10% significance level for nine out of 17 countries, providing solid evidence for a decline in the persistence of real exchange rates. However, the decline is not sufficient for PPP, meaning we fail to reject the unit root hypothesis even in the latter period for all 17 countries. In addition, our rolling-window estimates show that the real exchange rate of many countries have experienced a sharp drop in their persistence once we use samples starting from the mid-1980s. Finally, we examine the relationship between the dynamics of PPP deviation persistence and several economic variables and confirm that the speed of convergence of PPP deviations is highly related to economic/financial integration and world economic stabilization.     

Deviation from Purchasing Power Parity: Evidence from Malaysia, 1973–1997

This paper presents an empirical test of Purchasing Power Parity (PPP) applied to the Malaysia ringgit for the period from 1973 (CPI) and 1984 (WPI) to 1997. Consistent with other research findings, it is detected that real exchange rate follows a random walk. Using multivariate cointegration methodology for the long-run relationship between real exchange rate and certain macro-economic variables, the study provides evidence supporting a long-run relationship between the real exchange rate and the current account balance and government spending, the last two variables have been not included in previous studies of this economy. The causality test between real exchange rate with the current account balance and government spending, however, does not receive support from the error-correction model. This suggests that both government spending and current account balance are not adequate to explain the changes in ringgit real exchange rate. The puzzle still remains unsolved.