testing for the long run relationship between nominal interest rates and inflation using cointegration techniques 1989 testing for the long run relationship between nominal interest rates and inflation using cointegration techniques applied economics vol 21 no 4 pp 439 447

day of the week effects and asset returns the number of empirical studies using daily stock returns is rapidly increasing researchers generally assume that the distribution of stock returns is identical for all days of the week a convenient statistical assumption but not a necessary condition of market equilibrium nevertheless there are reasons to suspect that the distribution of returns may vary according to the day of the week the most obvious is the impact of weekends on monday s return since monday s return is calculated over three instead of one calender day the mean and variance may well be higher on monday compared with any other daily return perhaps three times as large previous research has examined the daily distribution of stock returns for a monday effect while fama 1965 does not compare daily mean returns he does report that monday s variance is about 20o greater than other daily returns with a traditional distributional assumption regarding the returns on a financial asset specifies that the expected returns are identical for all days of the week contrary to this plausible assumption this paper discovers that the expected returns on common stocks and treasury bills are not constant across days of the week the most notable evidence is for monday s returns where the mean is unusually low or even negative several explanations of the results are investigated but none proves satisfactory aside from documenting significant day of the week effects the implications of the results for tests of market efficiency are examined while market adjusted returns continue to exhibit day of the week effects these effects are no longer concentrated on monday during the last year we have had many conversations with our colleagues throughout the professions we are particularly thankful to the participants at sessions of the western and american finance associations where preliminary versions of this paper were presented special thanks are due to gene fama gailen hite jon ingersoll robert jarrow merton miller clifford smith and rex thompson the expert research assistance of frank rabinovitch and youngsup yun is gratefully acknowledged 1 the list of papers using daily stock returns is too long to name recent examples include charest 1978 dodd 1980 banz 1981 and reinganum 1981

a panic analysis on regional and sectoral inflation the spanish case this article studies the stochastic properties of several inflation rates for the spanish economy using the consumer price index cpi for the 17 regions and 12 groups of goods and services and the producer price index ppi for 26 industrial sectors to this end we employ the panel analysis of nonstationarity in idiosyncratic and common components panic approach proposed by bai and ng 2004 2010 this methodology enables us to decompose the observed inflation rate series into a common and an idiosyncratic component thus allowing us to identify the exact source of nonstationarity our analysis provides strong evidence of the presence of a common stochastic trend driving the observed series forming the panel of cpi based inflation rates for the regions this coupled with the presence of a jointly stationary idiosyncratic component implies the existence of pairwise cointegration across the regional cpi based inflation rates which show a clear pattern of convergence over time this gives an indicat

the effect of time induced stress on financial decision making in real markets the case of traffic congestion abstract we study the role of stress induced by time constraints on investor decision making in real financial markets we use unexpected traffic congestion as a stress trigger our dependent variable is the slope of the implied volatility function ivf of options on russian trading system index rtsi futures at the left hand side of the volatility smile cf bollen and whaley 2004 controlling for relevant factors we find that this slope at the opening of the main trading session is higher subsequent to morning traffic jams suggesting that investors under stress assign higher weights to extreme loss scenarios this effect is economically exploitable before transaction costs

disaggregate evidence on spanish inflation persistence this article investigates the degree of persistence of different inflation rates for the spanish economy using the consumer price index cpi for the aggregate as well as for the regions provinces

the relevance of supply shocks for inflation the spanish case the methodology applied in this article to the spanish economy is based on ball and mankiw 1995 these authors assume that a good proxy for supply shocks is the third moment of the price changes distribution the main data used are the monthly consumer price indexes of each region disaggregated in 57 categories for the 1993 2005 period we estimate the relation between mean inflation and the higher moments of the distribution including several control variables our results point out that spanish regions show a common pattern with regard to nominal rigidities and that spanish inflation is vulnerable to supply shocks

the predictive power of implied volatility evidence from 35 futures markets abstract using data from 35 futures options markets from eight separate exchanges we test how well the implied volatilities ivs embedded in option prices predict subsequently realized volatility rv in the underlying futures we find that for this broad array of futures options iv performs well in a relative sense for a large majority of the commodities studied the implieds outperform historical volatility hv as a predictor of the subsequently rv in the underlying futures prices over the remaining life of the option indeed in most markets examined regardless of whether it is modeled as a simple moving average or in a garch framework hv contains no economically significant predictive information beyond what is already incorporated in iv these findings add to previous research that has focused on currency and crude oil futures by extending the analysis into a very broad array of contracts and exchanges our results are consistent with the hypothesis that futures options markets in general with their minimal trading frictions are efficient

international evidence on the robustness of the day of the week effect consistent with connolly s 1989 1991 evidence this study finds that sample size and or error term adjustments render u s day of the week effects statistically insignificant in contrast day of the week effects in seven european countries and in canada and hong kong are robust to individual sample size or error term adjustments and day of the week effects in five european countries survive the simultaneous imposition of both types of adjustments in most countries where day of the week effects are robust however the effects are statistically significant in not more than two weeks out of the month these findings are inconsistent with explanations of the day of the week effect based on institutional differences or on the arrival of new information thus in the absence of other potential explanations already dismissed by jaffe and westerfield 1985 evidence in this study further complicates the international day of the week effect puzzle

is there a unit root in the inflation rate new evidence from panel data models with multiple structural breaks in this article we examine whether or not the inflation rate for 17 oecd countries can be modelled as a stationary process we find that 1 conventional univariate unit root tests without any structural breaks generally reveal that the inflation rate contains a unit root 2 the kpss univariate test with multiple structural breaks reveals that for 10 out of 17 countries inflation is stationary and 3 the kpss panel unit root test reveals strong evidence for stationarity of the inflation rate for panels consisting of countries which were declared nonstationary by univariate tests

an examination of the robustness of the weekend effect this paper analyzes the robustness of the day of the week dow and weekend effects to alternative estimation and testing procedures the results show that sample size can distort the interpretation of classical test statistics unless the significance level is adjusted down ward specification tests reveal widespread departures from ols assumptions hypothe sis tests results are reported using robust econometric methods and a garch model the strength of the dow and weekend effect evidence appears to depend on the estimation and testing method both effects seem to have disappeared by 1975

the weekend effect on the distribution of stock prices abstract evidence of weekend effects on the distribution of security returns suggests that returns are generated by a process operating closer to trading time rather than calendar time in contrast accumulation of interest over the weekend follows a calendar time process since both the variance of returns and the interest rate are important parameters of the black scholes option pricing model this paper suggests that the model be stated to account for this by utilizing a trading time variance and a calendar time interest rate empirical evidence indicates that this allows the model to better explain market option prices

inflation stationarity during latin american inflation insights from unit root and structural break analysis inflation stationarity has important theoretical and policy implications yet most of the literature has focused on low inflation countries this article investigates inflation stationarity in brazil argentina chile mexico and bolivia during a hyperinflationary period from 1980 to 2004 we test for structural breaks in inflation discuss the breaks in terms of changes in monetary regimes and test if accounting for these structural breaks changes the nonstationarity results for those nations that fail the traditional augmented dickey fuller adf test for inflation all five are found to have inflation rates that are i 0 once the structural breaks analysis is incorporated into our unit root tests

distress rentals and the land rental market as a safety net contract choice evidence from tigray ethiopia rural households in the semiarid northern ethiopian highlands are net buyers of food crop failure due to erratic and unpredictable rainfall occurs frequently and leads to food shortages and income shocks the renting out of land may be one of the coping responses of households exposed to shocks we developed a theoretical household model for poor landlord households capturing their contract choice response to downside production shocks we tested econometrically whether contract choice may depend on poverty capital constraints production risk and random shocks the multinomial logit model estimates show that poor households experiencing random shocks are more likely to choose fixed rent contracts as a distress response to shocks suggesting that fixed rent contracts may be used to meet immediate needs but at the expense of future incomes we also found that fixed rent contracts are preferred when ex ante production risk is low while sharecropping is more likely where production risk is high finally we found an indication that the choice of a fixed rent contract as a coping response to shocks comes as a last resort after all other means of coping are exhausted

the ex ante and ex post price effects of quarterly earnings announcements reflected in option and stock prices the subject of this study is the effect of investors anticipations of impending informative disclosures on the behavior of option and stock prices our approach introduced in a previous paper patell and wolfson 1979 and substantially extended here represents the following significant departure from traditional information content studies instead of analyzing security price reactions to announcements we analyze preannouncement option prices in order to discern investors beliefs about the range of possible stock price reactions expected to accompany a forthcoming disclosure whose actual content is not yet known in the tests reported here we focus on quarterly earnings announcements as disclosure events whose timing is predictable and we attempt to detect their systematic influence on the relationship between stock and option prices our operational definition of information content emphasizes changes in the variability of common stock returns in response to earnings disclosures while market efficiency precludes investors from predicting the direction of the stock price change which will accompany a future earnings announcement it is likely that investors will anticipate increased price variability at the time of disclosure and indeed several studies have documented announcement date increases in stock price volatility

comparative performance of the black scholes and roll geske whaley option pricing models the original black scholes bs 2 european call option pricing model does not take account of divided payments on the underlying stock and does not allow for the possibility of early exercise that may be optimal when the stock pays dividends black 1 has suggested that the original bs model can be modified to take account of dividends and sharpe 14 predicts that this modified or pseudo american bs approach while not exact is probably sufficient for many listed options

a characterization of the daily and intraday behavior of returns on options the daily and intraday behavior of returns on chicago board options exchange options is examined option returns contain systematic patterns even after adjusting for patterns in the means and variances of the underlying assets this is consistent with the hypothesis that informed trading in options can make the order flow in the options market informative about the value of the underlying asset making options nonredundant the intraday patterns in adjusted option return variances are further consistent with a model of strategic trading by informed and discretionary liquidity traders this paper examines the daily and intraday behavior of returns on options we have two goals our first objective is to identify systematic patterns in the means and variances of daily and intraday returns on options our second objective is to decompose option returns into patterns that are related to the means and variances of the underlying stocks and by inference those patterns that are independent of patterns in the means and variances of the underlying assets 1 our work is important for a number of reasons first options have become as important as common stocks yet there is no detailed investigation of the behavior of returns on options second it is important to identify similarities and differences in return patterns across different securities and market structures an understanding of these similarities and differences would allow us to develop better models of returns that capture these properties closely related to this it is instructive to examine option returns in light of the partial equilibrium models we use to value them specifically are the return patterns in options driven exclusively by the underlying stocks or do option returns contain patterns of their own identifying independent yet similar patterns in options returns may lead to an identification of factors that are common across two different market structures the new york

overreactions in the options market this paper examines the term structure of options implied volatilities using data on s p 100 index options because implied volatility is strongly mean reverting the implied volatility on a longer maturity option should move by less than one percent in response to a one percent move in the implied volatility of a shorter maturity option empirically this elasticity turns out to be larger than suggested by rational expectations theory long maturity options tend to overreact to changes in the implied volatility of short maturity options are investors rational do they behave like bayesian statisticians when it comes to incorporating new information into asset prices proponents of the efficient markets hypothesis would answer this question in the affirmative many others however believe that bayesian rationality is a poor description of investor behavior and that as a consequence asset prices tend to be informationally inefficient one way in which inefficiencies might arise is through the overreactions of traders to the arrival of new information 1 this possibility is raised by experimental and survey findings which indicate that people have a systematic tendency to overemphasize recent data at the expense of other information when making projections 2 the objective of this paper is to search for evidence of such overreactive behavior in a semingly peculiar place the options market options may appear to be unlikely candidates for overreaction because unlike primary securities their prices are closely tied down by arbitrage considerations as black and scholes 1973 demonstrate if stock price volatility is known options prices are completely determined any deviation from the prescribed value implies a riskless profit opportunity however given that volatility is in fact unknown and changing options do retain something of an independent nature not wholly redundant with their underlying stocks options can be thought of as reflecting a speculative market in volatility the implied volatility on a given option obtained by inverting a

testing between competing models of sharecropping the marshallian approach assumes a prohibitively high cost of monitoring the sharecropper s activities while the monitoring approach argues that landlords stipulate and effectively monitor sharecroppers activities i present new evidence using detailed data collected from eight indian villages most tenants own some land of their own this provides a controlled environment in studying the impact of contractual arrangements the differences in input and output intensities on owned minus sharecropped land of the same household are found to be sizable and significant suggesting a rejection of the monitoring approach and supporting the notion of the marshallian productive inefficiency of sharecropping

more powerful panel data unit root tests with an application to mean reversion in real exchange rates unit root tests seeking mean or trend reversion are frequently applied to panel data we show that more powerful variants of commonly applied tests are readily available moreover power gains persist when the modifications are applied to bootstrap procedures that may be employed when cross correlation of a rather general sort among individual panel members is suspected copyright 2004 john wiley sons ltd

how much can marketability affect security values how marketability affects security prices is one of the most important issues in finance we derive a simple analytical upper bound on the value of marketability using option pricing theory we show that discounts for lack of marketability can potentially be large even when the illiquidity period is very short this analysis also provides a benchmark for assessing the potential costs of exchange rules and regulatory requirements restricting the ability of investors to trade when desired furthermore these results provide new insights into the relation between discounts for lack of marketability and the length of the marketability restriction

abusa the structural history of an economic contract this speculative essay seeks an interpretation of abusa a share cropping arrangement which has been of fundamental importance in the development of the ghanaian cocoa industry according to theoretical expectations such an arrangement is both inefficient and inequitable a pre modern or pre capitalist productive relationship which will inevitably yield to a pattern of fixed rents and wage labour here the role of abusa in the spectacular growth of the cocoa economy and in its recent decline is examined with reference to the development of individual contracts it is argued that this ontogenetic development of abusa is structured by the changing domestic circumstances of farm owner and farm worker their competing interests in a maturing cocoa farm are negotiated and expressed in a sequence of contractual arrangements which gives the worker increasing access to the land and the product of his own labour it is suggested that if the evolution of productive relations towards more evidently capitalist

nonlinearity and stationarity of inflation rates evidence from the euro zone countries earlier studies hardly reject the hypothesis of a unit root in inflation few studies have examined the possibility of nonlinearity in inflation and tested nonlinear stationarity of the inflation rates this study thus intends to fill the gap this study utilizes the tests for nonlinearity along with the unit root tests that allow for nonlinearity in the variables to examine the stationarity of inflation rates of 12 european countries that formed the euro zone ez later in the sample period the results suggest that the majority of these countries inflation rates can be characterized by mean reversion during the floating exchange rate period many of them appear to be nonlinear stationary this finding is essential in conducting applied economic studies for these countries when constructing models whose validity relies on whether or not inflation is stationary the results of this study also imply that shocks to inflation have a transitory effect on inflation in the euro area therefore it would be le

external imbalances in the eurozone the paper examines the extent to which current account imbalances of euro area countries are related to intra euro area factors and to external trade shocks we argue that the traditional explanations for the rising imbalances are correct but are incomplete we uncover a large impact of declines in export competitiveness and asymmetric trade developments vis a vis the rest of the world x96 in particular vis a vis china central and eastern europe and oil exporters x96 on the external balance of euro area debtor countries while current account imbalances of euro area deficit countries vis a vis the rest of the world increased they were financed mostly by intra euro area capital inflows in particular by the purchase of government and financial institutions securities and cross border interbank lending which permitted external imbalances to grow over time ruo chen gian maria milesi ferretti and thierry tressel

role of speculative short sales in price formation the case of the weekend effect we argue that short sellers aiect prices in a signi cant and systematic manner in particular we contend that speculative short sales contribute to the weekend eiect the inability to trade over the weekend is likely to cause these short sellers to close their speculative positions on fridays and reestablish new short positions on mondays causing stock prices to rise on fridays and fall on mondays we nd evidence in support of this hypothesis based on a comparison of high short interest stocks and low short interest stocks stocks with and without actively traded options ipos zero short interest stocks and highly volatile stocks in this paper we empirically examine whether speculative short sales aiect prices in a systematic manner the focus is on the weekend eiect that has remained an unexplained anomaly beginning with french 1980 and gibbons and hess 1981 there is much evidence in support of higher returns on fridays and lower returns on mondays keim and stambaugh 1984 nd that friday returns are lower when there is saturday trading ariel 1990 nds that a signi cantly larger number of stocks rises preholiday than postholiday empirical evidence related to more recent periods points to an insigni cant weekend eiect for large rms but continuance of the weekend eiect for an equally weighted index as documented herein 1 many potential explanations of the weekend eiect have been proposed and investigated measurement errors gibbons and hess 1981 and keim and stambaugh 1984 delay between trading and settlement in stocks dyl and martin 1985 and lakonishok and levi 1982 specialist related biases in prices keim and stambaugh timing of corporate releases after friday s close damodaran 1989 reduced institutional trading and greater individual trading on mondays

econometric models of asymmetric price transmission abstract in this paper we review the existing empirical literature on price asymmetries in commodities providing a way to classify and compare different studies that are highly heterogeneous in terms of econometric models type of asymmetries and empirical findings relative to the previous literature this paper is novel in several respects first it presents a detailed and updated survey of the existing empirical contributions on price asymmetries in the transmission mechanism linking input prices to output prices second this paper presents an extension of the traditional distinction between long run and short run asymmetries to new categories of asymmetries such as contemporaneous impact distributed lag effect cumulated impact reaction time equilibrium and momentum equilibrium adjustment path regime effect regime equilibrium adjustment path each empirical study is then critically discussed in the light of this new classification of asymmetries third this paper evaluates the relative merits of the most popular econometric models for price asymmetries namely autoregressive distributed lags partial adjustments error correction models regime switching and vector autoregressive models finally we use the meta regression analysis to investigate whether the results of asymmetry tests are not model invariant and find which additional factors systematically influence the rejection of the null hypothesis of symmetric price adjustment the main results of our survey can be summarized as follows i each econometric model is specialized to capture a subset of asymmetries ii each asymmetry is better investigated by a subset of econometric models iii the general significance of the f test for asymmetric price transmission depends mainly on characteristics of the data dynamic specification of the econometric model and market characteristics overall our empirical findings confirm that asymmetry in all its forms is very likely to occur in a wide range of markets and econometric models

why do option returns change sign from day to night abstract average delta hedged returns for standard poor s 500 index options are large 0 7 per day when we decompose these option returns into intraday and overnight components average close to open returns are 1 per day and open to close returns are positive 0 3 a similar return pattern holds for all maturity and moneyness categories and equity options these positive intraday returns are particularly difficult to explain however our results are consistent with option prices failing to account for the well known fact that stock volatility is substantially higher intraday than overnight these findings help explain price formation in the options market

transaction costs risk aversion and the choice of contractual arrangements publisher summary this chapter discusses transaction costs risk aversion and the choice of contractual arrangements every transaction involves a contract and the transactions conducted in the marketplace entail outright or partial transfers of property rights among individual contracting parties the contractual arrangements through which these transfers are negotiated are several and varied the chapter presents a theory that states that economic efficiency is the same under various land tenure arrangements subject to the constraint of private property rights although transaction costs exist in the real world the theory enables the understanding of much of the farming behavior however the presence of a variety of contractual arrangements under the same constraint of competition poses the question of the choice of these arrangements if a firm can increase efficiency in production by employing productive resources of more than one resource owner a contract to combine the resources will be obtained the formation of the contract involves partial transfers of property rights in one form or another such as leasing hiring or mortgaging

on the valuation of american call options on stocks with known dividends both the roll and the geske equations for the valuation of the american call option on a stock with known dividends are incorrectly specified this note presents the corrected valuation formula explains the misspecifications and provides a numerical example

a methodology for assessing model risk and its application to the implied volatility function model we propose a methodology for assessing model risk and apply it to the implied volatility function ivf model this is a popular model among traders for valuing exotic options our research is different from other tests of the ivf model in that we reflect the traders practice of using the model for the relative pricing of exotic and plain vanilla options at one point in time we find little evidence of model risk when the ivf model is used to price and hedge compound options however there is significant model risk when it is used to price and hedge some barrier options

stock price clustering on option expiration dates abstract this paper presents striking evidence that option trading changes the prices of underlying stocks in particular we show that on expiration dates the closing prices of stocks with listed options cluster at option strike prices on each expiration date the returns of optionable stocks are altered by an average of at least 16 5 basis points which translates into aggregate market capitalization shifts on the order of 9 billion we provide evidence that hedge rebalancing by option market makers and stock price manipulation by firm proprietary traders contribute to the clustering

pricing options in an extended black scholes economy with illiquidity theory and empirical evidence this article studies the pricing of options in an extended black scholes economy in which the underlying asset is not perfectly liquid the resulting liquidity risk is modeled as a stochastic supply curve with the transaction price being a function of the trade size consistent with the market microstructure literature the supply curve is upward sloping with purchases executed at higher prices and sales at lower prices optimal discrete time hedging strategies are then derived empirical evidence reveals a significant liquidity cost intrinsic to every option copyright 2006 oxford university press

anticipation of quarterly earnings announcements a test of option market efficiency abstract this study tests chicago board options exchange efficiency by examining option price behavior in the weeks surrounding a firm s quarterly earnings announcement the evidence presented here suggests that a first order autoregressive seasonal process describes quarterly earnings behavior and demonstrates that the information content of an earnings announcement is fully incorporated in option prices by the end of the announcement week

underreaction overreaction and increasing misreaction to information in the options market this paper investigates options market reaction to changes in the instantaneous variance of the underlying asset there are three main findings first options market investors underreact to individual daily changes in instantaneous variance second these same investors overreact to periods of mostly increasing or mostly decreasing daily changes in instantaneous variance third they tend to underreact overreact to current daily changes in instantaneous variance that are preceded mostly by daily changes of the opposite same sign the third finding can reconcile the first two and is also consistent with well established cognitive biases

the spread of sharecropping in tuscany the political economy of transaction costs land tenure is central to many agricultural transformations the author examines one of these transformations the spread of sharecropping in late medieval and early modern tuscany previous research suggested that sharecropping spread as agricultural relations were refeudalized in contrast the author s analyses of fixed term and share term leasing sharecropping show that landlords used sharecropping when it lowered their overall costs of labor supervision and land management however to explain the spread of sharecropping the florentine political economy which created particular patterns of land management costs and labor supervision costs must also be considered florence was a well developed center for urban manufacturing landlords were frequently urban merchants and they resided in florence these factors were crucial in shaping agricultural relations landlords use of sharecropping to reduce the overall costs of land management and labor supervision increased as the distance from florence the site of landlords principal activities increased as the size of farms increased and when crops had high costs of labor supervision and land management thus the use of sharecropping to lower costs associated with agricultural production must be considered in the context of the tuscan political economy

option mispricing around nontrading periods we find that option returns are significantly lower over nontrading periods the vast majority of which are weekends our evidence suggests that nontrading returns cannot be explained by risk but rather are the result of widespread and highly persistent option mispricing driven by the incorrect treatment of stock return variance during periods of market closure the size of the effect implies that the broad spectrum of finance research involving option prices should account for nontrading effects our study further suggests how alternative industry practices could improve the efficiency of option markets in a meaningful way

the efficiency of share contracts in ghana s cocoa industry social anthropologists have contributed significantly to our understanding of the consistency between observed labour contracts in the ghana cocoa industry and the cultural historical development of the country this article contributes to the ongoing research efforts in this area by demonstrating that the observed labour contracts are also efficient and consistent with the predictions of economic theory it concludes that joint efforts by anthropologists and economists may be one effective way to proceed in seeking insights into a labour market that is so deeply rooted in the culture of a people

weekend effects on stock returns a note some researchers have apparently been surprised to discover that the distribution of stock returns depends on the day of the week kenneth french 3 for example in testing whether daily stock returns are generated by a trading time or calendar time hypothesis provided convincing evidence of a negative market return on mondays as french carefully notes this finding runs counter to both hypotheses since a trading time view would have expected stock returns equal on different days and a calendar time view would have higher expected returns on monday to compensate for the longer holding period in this paper we offer a partial explanation for the apparently puzzling discovery of different daily returns we argue that the expected stock returns as measured for example from closing to closing prices should depend on the day of the week in general we argue that the expected returns on mondays should be lower than would be implied simply by a trading time or calendar time model and the returns on fridays should be higher in addition we anticipate that holidays will have complex effects on stock returns on other days of the week our argument is based on the delay between trading and settlements in stocks and in clearing checks the explanation that we offer for different measured daily returns does not contradict the efficient market hypothesis as correctly adjusted expected returns should not differ according to the day of the week

valuation of american call options on dividend paying stocks empirical tests abstract this paper examines the pricing performance of the valuation equation for american call options on stocks with known dividends and compares it with two suggested approximation methods the approximation obtained by substituting the stock price net of the present value of the escrowed dividends into the black scholes model is shown to induce spurious correlation between prediction error and 1 the standard deviation of stock return 2 the degree to which the option is in the money or out of the money 3 the probability of early exercise 4 the time to expiration of the option and 5 the dividend yield of the stock a new method of examining option market efficiency is developed and tested

the overvaluation of purchasing power parity abstract recent panel studies of purchasing power parity have reported strong evidence of mean reversion in real exchange rates however these studies fail to control for cross sectional dependence in the data this failure has dramatic consequences raising the significance level of tests with a nominal size of 5 percent to as much as 50 percent it is shown in this paper that controlling for cross sectional dependence no evidence against the random walk null can be found in panels of up to 64 real exchange rates this finding cannot be attributed to low power as there is ample power in panels of this size to reject the unit root null