48 UDC: 339.743(437.1/.2:497.4) In this paper we test the theory of purchasing power parity for the Czech Republic and Slovenia in comparison to Austria, Germany, France and Italy by employing data from January 1992 to December 2001. Results of unit root tests indicate that the eight time series of the real exchange rates of the koruna and the tolar are integrated of order one. Though some cointegration was found among the nominal exchange rates and selected consumer price indices, the presented results do not support the theory of purchasing power parity in any of the two observed economies. Key words: purchasing power parity, exchange rate, cointegration A b s t r a c t UDK: 339.743(437.1/.2:497.4) V tem prispevku preverjamo teorijo paritete kupne moči na Češkem in v Sloveniji v primerjavi z Avstrijo, Nemčijo, Francijo in Italijo na osnovi podatkov od januarja 1992 do decembra 2001. Rezultati testov enotnega korena so pokazali, da je vseh osem časovnih vrst realnega deviznega tečaja krone in tolarja integriranih prvega reda. Čeprav smo dokazali kointegracijo med nominalnimi deviznimi tečaji in indeksi cen življenjskih potrebščin, dobljeni rezultati ne potrjujejo teorije paritete kupne moči. Ključne besede: pariteta kupne moči, devizni tečaj, kointegracija I z v l e č e k JEL: E31, F31, F41 Darja Boršič, Ph.D. Jani Beko, Ph.D. University of Maribor Faculty of Economics and Business Pariteta kupne moči na Češkem in v Sloveniji: Empirično preverjanje PURCHASING POWER PARITY IN THE CZECH REPUBLIC AND SLOVENIA: AN EMPIRICAL TEST NG, ŠT. 1–2/2007 IZVIRNI ZNANSTVENI ČLANKI/ORIGINAL SCIENTIFIC PAPERS 5 1 Introduction In the last few decades, the validity of the theory of purchasing power parity (PPP) has been scrutinized in numerous empirical papers. Froot and Rogoff (1995), Sarno and Taylor (2002) and Taylor and Taylor (2004) present reviews of relevant literature. Explicit research on PPP theory has yielded varying results, partly as a result of the different estimation techniques, observation periods and data sets that have been employed; and partly because of factors that complicate the law of one price, such as obstacles to international trade, the inclusion of transaction costs, pricing-to-market strategy, discretionary exchange rate management and changes in the structure of price indices. Researchers, however, agree on two issues related to this exchange rate theory (Rogoff 1996): first, real exchange rates tend to converge on levels predicted by PPP in the long run; and second, short-run deviations from the PPP relationship are substantial and variable. While there is a great deal of empirical work on PPP theory for developed market economies, similar studies for transition countries are rather rare. Varamini and Lisachuk (1998) analyze the case of Ukraine for the period 1992–1996 and gain evidence in favor of PPP, despite some short-run deviations. Christev and Noorbakhsh (2000) deal with six Central European Countries (Bulgaria, the Czech Republic, Hungary, Poland, Romania, and Slovakia) in the period from 1991 to 1998. They find moderate proof of long-run equilibrium of prices and exchange rates, but conditions for the law of one price are violated. Pufnik (2002) and Payne et al. (2005) examine the Croatian economy, finding no support for PPP theory. Barlow (2004) also tests the theory for the Czech Republic, Poland and Romania using Johansen cointegration tests, but the conclusions for the time period 1994–2000 are mixed regarding different combinations of the exchange rates of selected countries. The present paper aims to expand the investigation of PPP for two advanced transition countries: the Czech Republic and Slovenia. Considering different views on how the process of economic transformation since the beginning of the nineties and its effects on reforming countries’ price mechanisms are compatible with rigorous assumptions of the theory of PPP (see Brada 1998), there is an obvious need for further empirical evaluation to supply clear-cut evidence on macroeconomic forces that govern the exchange rate behavior in the aforementioned economies. Because the majority of transition countries have undergone several phases of economic restructuring, these most likely also triggered shifts in their equilibrium real exchange rates. This suggests that, when comparing developed market economies with those still under economic reforms, the degree of a country’s similarity, especially in terms of trade pattern, level of development and the structure of relative prices, could importantly affect the assessment of PPP. In order to provide detailed estimates, this study is based on separate testing of PPP in the Czech Republic and Slovenia with reference to their main trading partners from the EU–15, i.e. Austria, Germany, France and Italy. From 1992 to 2001, these four countries accounted for 56 percent of Slovenia’s exports and imports. In the same period their share in Czech exports amounted to 48 percent and they also covered 51 percent of Czech imports on average. ´´ 49 BORŠIČ, BEKO: PURCHASING POWER PARITY IN THE CZECH REPUBLIC AND SLOVENIA: AN EMPIRICAL TEST The paper consists of three additional sections. In Section 2, after describing the general model of PPP and presenting the relevant data, the stationarity of real exchange rates is dissected. Section 3 proceeds with a search for cointegration among nominal exchange rates, domestic consumer prices and foreign consumer prices by relying on Johansen’s methodology (1991). Concluding remarks are given in the final section. 2 The Model of PPP and Unit Root Tests of Real Exchange Rates The general model of testing for PPP can be specified in the following form (Cheung and Lai 1993): et = .0 + .1pt + .2pt* + .t (1), where et stands for nominal exchange rates, defined as the price of foreign currency in the units of domestic currency; pt denotes domestic price index and pt* foreign price index; while .t stands for the error term showing deviations from PPP. All the variables are given in logarithmic form. In the strictest version of PPP, there are the following assumptions: .0=0, .1=1, .2=-1. The symmetry restriction applies such that absolute values of .1 and .2 are equal, whereas the limitation of being equal to one is called the proportionality restriction (Froot and Rogoff 1995). Throughout this study we utilized monthly data series for Slovenia from January 1992 and for the Czech Republic from January 1993 to December 2001 (for both countries), when the euro was put into circulation. Primary data included monthly averages of nominal exchange rates and consumer price indices gathered from the central banks of individual countries. Each of the exchange rates has been defined as the koruna (CZK) or tolar (SIT) cost of a unit of foreign currency. Consumer price indices used in this study for Slovenia refer to January 1992, while for the Czech Republic they refer to January 1993. The empirical analysis starts off with the most restrictive version of Equation 1, .1=1, .2=-1, that is, with testing the properties of real exchange rates. In the context of relative PPP, the movements in nominal exchange rates are expected to compensate for price level shifts. Thus, real exchange rates should be constant over the long run and their time series should be stationary (Parikh and Wakerly 2000). The real exchange rates are a function of nominal exchange rates and relative price indices in two observed economies. They are calculated from the nominal exchange rates using the consumer price indices: REt = Et (Pt*/ Pt) (2), where REt stands for the real exchange rate, Et is the price of a foreign currency in units of domestic currency, and Pt* and Pt represent the foreign price index and the domestic price index, respectively. Taking the logarithms of Equation 2, the real exchange rates are defined as: ret = et + pt* – pt (3). The graph of a stationary time series is not supposed to reflect any kind of a time trend. Figure 1 presents the graphs of real exchange rates of the Czech koruna (CZK) and the Slovenian tolar (SIT) in comparison to the Austrian schilling (ATS), the German mark (DEM), the French franc (FRF) and the Italian lira (ITL). The graphs of exchange rates show that after an initial real depreciation, from 1996 onwards, the Slovenian tolar experienced a systematic real appreciation in comparison to the currencies of the selected market economies. As can be seen from Figure 1, the regular real appreciation of the Czech koruna against the currencies of the four developed market economies in the 1993–2001 period was partly interrupted only in 1997 reflecting exchange rate instability due to a domestic currency crisis. Such a pattern in real exchange rate movements is explained in the literature by a range of factors, including inherited macroeconomic imbalances in transition countries, mixed performance of chosen exchange rate arrangements, monetary difficulties arising from huge capital inflows, the inflationary impact of wage and price adjustments, and real exchange rate appreciation due to the catching-up process (Halpern and Wyplosz 1997; Brada 1998). For checking the stationarity of real exchange rates, the augmented Dickey-Fuller (1979) test was used, taking into account the following equation: t m i t t i t i Y ß ß t .Y .. Y . = - - . = + + + . + 1 1 2 1 (4), where ß1, ß2, . and .i are parameters of the test, t is linear time trend, Yt is the tested time series, .Yt-i=Yt-i-Yt-i-1 and m is selected so that the residuals (.t) are white noise. We test the null hypothesis H0: .=0, which implies that there is a unit root present and the time series is non-stationary. Following Barlow (2004), Equation 4 was estimated assuming ß2=0. In order not to unnecessarily lose too many observations in a relatively short time series, the orders of augmentation were set to m=6 for all tests of unit root by using critical values according to MacKinnon (1991). Campbell and Perron (1991) prefer determining the time lags according to a t-test. They argue that a VAR with a maximum number of lags should be carried out. If the last included lag is statistically significant, it is appropriate to use it in ADF regressions. The number of lags should be reduced as long as the last included lag is statistically significant. Also Ng and Perron (1995) argue that information-based rules (AIC, SIC) tend to select too low truncation lags, while the t-test is supposed to provide results with more robust size properties in models. In the present analysis, the estimates are obtained on the basis of time lags which correspond to the minimum value of the Akaike Information Criterion (AIC) and are in line with the t-test approach. Results of the augmented Dickey-Fuller test are shown in Table 1. Each calculation is stated twice, according to the time lag determined by the two approaches described above. Although AIC and the t-test select different time lags, the results of the ADF test using both selection criteria do not ´´ 50 NG, ŠT. 1–2/2007 IZVIRNI ZNANSTVENI ČLANKI/ORIGINAL SCIENTIFIC PAPERS Source: The Czech National Bank and Bank of Slovenia. Notes: L stands for logarithm, R for real; the next three letters (ATS, DEM, FRF, ITL) represent the currencies of Austria, Germany, France and Italy, respectively, while the last two letters (CZK, SIT) denote the currencies of the Czech Republic and Slovenia, respectively. 1992:01=100 for Slovenia, 1993:01=100 for the Czech Republic. Figure 1: Real Exchange Rates of the Czech koruna and the Slovenian tolar 51 BORŠIČ, BEKO: PURCHASING POWER PARITY IN THE CZECH REPUBLIC AND SLOVENIA: AN EMPIRICAL TEST contradict, but are rather similar. The figures show that the eight time series of the real exchange rates of the koruna and the tolar are integrated of order one, which means we cannot reject the hypothesis of the presence of the unit root. Thus, the ADF test confirms the graphical results of nonstationarity in the observed time series. 3 Cointegration Analysis and Comments on Results When all restraints in Equation 1 are omitted (.1.1, .2.-1), it becomes the least restrictive version of PPP. The only requirement that remains is the signs of the coefficients. This implies that we are looking for any linear relationship among the observed variables that has stationary properties. Taking into account the unstable characteristics of nonstationary time series, the existence of a stationary relationship among them is more important than deviations of coefficients from the strict theory of PPP (Liu 1992). If a cointegration among nominal exchange rates, domestic consumer prices and foreign consumer prices is found and it is presented by the cointegrating vector of (1, .1, .2) (Equation 1), the validity of the theory of PPP is proven. Since we are looking for a stationary linear combination of three variables, the Johansen cointegration test is appropriate to use. This method is based on a VAR and can be briefly described as follows (Johansen 1991): Yt = A1Yt-1 + …. + AmYt-m + BXt + .t, (5), where A1, …, Am and B are matrices and the parameters of the model, t ranges from 1 to T, Yt is a vector of k variables, which are integrated of the first order, Xt is vector of deterministic variables and .t is a vector of innovations. VAR in Equation 5 can be also written as: .Yt = .Yt-1 + . - = - . . 1 1 m i i t i Y + BXt + .t (6), where . =. - . = m i i A 1 and . = + . = - m j i i j A 1 (7). Matrix . contains information about long-run variation of the time series. According to the Granger representation theorem (Engle and Granger 1987; Johansen 1991), matrix . can be divided into k x r matrices . and . with rank of r (r.k-1), so that .=..’ if . also has reduced rank r