bulls bears and market sheep abstract a deterministic excess demand model of stock market behavior is presented that generates stochastically fluctuating prices and randomly switching bear and bull markets

garch inadequacy for modelling exchange rates empirical evidence from latin america this article checks for the adequacy of using garch models in exchange rate series using the hinich portmanteau bicorrelation test we find that a garch formulation or any of its variants fails to capture the data generating process of the main latin american exchange rates our results highlight the potential of having misleading public policy when estimates are based in garch types of models this article also complements recent similar findings encountered in european and asian economies

chaos in oil prices evidence from futures markets abstract we test for the presence of low dimensional chaotic structure in crude oil heating oil and unleaded gasoline futures prices from the early 1980s evidence on chaos will have important implications for regulators and short term trading strategies while we find strong evidence of non linear dependencies the evidence is not consistent with chaos our test results indicate that arch type processes with controls for seasonal variation in prices generally explain the non linearities in the data we also demonstrate that employing seasonally adjusted price series contributes to obtaining robust results via the existing tests for chaotic structure maximum likelihood methodologies that are robust to the non linear dynamics lend support for samuelson s hypothesis on contract maturity effects in futures price changes however the tests for chaos are not found to be sensitive to the maturity effects in the futures contracts the results are robust to controls for the oil shocks of 1986 and 1991

uncovering nonlinear structure in real time stock market indexes the s p 500 the dax the nikkei 225 and the ftse 100 this article tests for nonlinear dependence and chaos in real time returns on the world s four most important stock market indexes both the brock dechert scheinkman and the lee white and granger neural network based tests indicate persistent nonlinear structure in the series estimates of the lyapunov exponents using the nychka ellner gallant and mccaffrey neural net method and the zeng pielke and eyckholt nearest neighbor algorithm confirm the presence of nonlinear dependence in the returns on all indexes but provide no evidence of low dimensional chaotic processes given the sensitivity of the results to the estimation parameters we conclude that the data are dominated by a stochastic component

the effects of the international security environment on national military expenditures a multicountry study we consider the influence of countries external security environments on their military spending we first estimate the ex ante probability that a country will become involved in a fatal militarized interstate dispute using a model of dyadic conflict that incorporates key elements of liberal and realist theories of international relations we then estimate military spending as a function of the threat of armed interstate conflict and other influences arms races the defense expenditures of friendly countries actual military conflict democracy civil war and national economic output in a panel of 165 countries 1950 to 2000 we find our prospectively generated estimate of the external threat to be a powerful variable in explaining military spending a 1 percentage point increase in the aggregate probability of a fatal militarized dispute as predicted by our liberal realist model leads to a 3 percent increase in a country s military expenditures

exchange rate uncertainty and agricultural trade panel cointegration analysis for turkey this study addresses the impact of exchange rate levels and uncertainty on bilateral agricultural trade between turkey and 20 major trading partners using panel cointegration analysis for annual data covering the period 1980 2005 results show that i the exchange rate level is less robustly linked to trade volumes than is exchange rate uncertainty ii exchange rate uncertainty is associated with smaller trade volumes in both directions but more so for imports than for exports and iii income growth in turkey is associated with greater imports just as income growth among trading partners is associated with greater exports these findings provide some clues for understanding the recent patterns of turkish agricultural trade and suggest directions for future research

episodic nonlinearity and nonstationarity in alberta s power and natural gas markets abstract this paper uses a new method of testing for linear and nonlinear lead lag relationships between time series introduced by brooks and hinich brooks c and hinich m j cross correlations and cross bicorrelations in sterling exchange rates journal of empirical finance 20 1999 385 404 on alberta s natural gas and power markets the test based on the concepts of cross correlation and cross bicorrelation is used after pre whitening of the data to test for the existence of residual nonlinearity as well as the episodic nature of the nonlinearity our evidence points to a relatively rare episodic nonlinearity within and across the two series having important implications for forecasting these series

distinguishing between stochastic and deterministic behavior in foreign exchange rate returns further evidence abstract the nature of non linear dependence in hourly exchange rate returns is scrutinized while the brock dechert and scheinkman bds test results reject i i d behavior various correlation dimension estimates reveal little evidence in favor of a low dimensional attractor in the time series

complexity and the character of stock returns empirical evidence and a model of asset prices based on complex investor learning empirical evidence on the distributional characteristics of common stock returns indicates 1 a power law tail index close to three describes the behavior of the positive tail of the survivor function of returns pr r x x a reflection of fat tails 2 general linear and nonlinear dependencies exist in the time series of returns 3 the time series return process is characterized by short run dependence short memory in both returns as well as their volatility the latter usually characterized in the form of autoregressive conditional heteroskedasticity and 4 the time series return process probably does not exhibit long memory but the squared returns process does exhibit long memory we propose a model of complex self referential learning and reasoning amongst economic agents that jointly produces security returns consistent with these general observed facts and which are supported here by empirical results presented for a benchmark sample of 50 stocks traded on the new york stock exchange the market we postulate is populated by traders who reason inductively while compressing information into a few fuzzy notions that they can in turn process and analyze with fuzzy logic we analyze the implications of such behavior for the returns on risky securities within the context of an artificial stock market model dynamic simulation experiments of the market are conducted from which market clearing prices emerge allowing us to then compute realized returns we test the effects of varying values of the parameters of the model on the character of the simulated returns the results indicate that the model proposed in this paper can jointly account for the presence of a power law characterization of the positive tail of the survivor function of returns with exponent on the order of three for autoregressive conditional heteroskedasticity for long memory in volatility and for general nonlinear dependencies in returns

tick size the compass rose and market nanostructure abstract economists have begun using methods borrowed from the physical sciences to search for non linearities in economic and financial data the so called phase portrait from chaos theory in which the values of a time series are plotted against their delayed values is one of the techniques employed for this purpose it has recently been shown however that when returns on traded assets are plotted in this manner in two or three dimensional space surprising patterns arise which seriously distort the conclusions that can be drawn about the underlying data these patterns which resemble a compass rose reflect the microstructure of the market or more specifically the finite size of the ticks by which prices can change in a market the present paper clarifies the reason for this phenomenon it is shown that within the microstructure there exists nanostructure that becomes visible only when the computations are performed without approximation high frequency data from a foreign exchange market are used to illustrate this phenomenon

a note on the wang and wang measure of the quality of the compass rose abstract h wang and c wang visibility of the compass rose in financial asset returns a quantitative study j bank financ 26 2002 1099 1111 derive a measure of the visibility of the radial patterns that appear in a plot of current and past returns which are more commonly known as the compass rose in theory this measure should be positively related to the tick volatility ratio in practice however we find that this relationship does not hold for higher tick volatility ratios that are common to stock market data thus the use of this measure is limited in real world applications we propose a correction factor that improves the behaviour of the quality measure over higher tick volatility ratios however further research is required to fully identify and correct the problem

testing for non linear structure in an artificial financial market abstract we present a stochastic simulation model of a prototype financial market our market is populated by both noise traders and fundamentalist speculators the dynamics covers switches in the prevailing mood among noise traders optimistic or pessimistic as well as switches of agents between the noise trader and fundamentalist group in response to observed differences in profits the particular behavioral variant adopted by an agent also determines his decision to enter on the long or short side of the market short run imbalances between demand and supply lead to price adjustments by a market maker or auctioneer in the usual walrasian manner our interest in this paper is in exploring the behavior of the model when testing for the presence of chaos or non linearity in the simulated data as it turns out attempts to determine the fractal dimension of the underlying process give unsatisfactory results in that we experience a lack of convergence of the estimate explicit tests for non linearity and dependence the bds and kaplan tests also give very unstable results in that both acceptance and strong rejection of iidness can be found in different realizations of our model all in all this behavior is very similar to experience collected with empirical data and our results may point towards an explanation of why robustness of inference in this area is low however when testing for dependence in second moments and estimating garch models the results appear much more robust and the chosen garch specification closely resembles the typical outcome of empirical studies

international financial volatility and agricultural commodity trade a primer recent international financial crises east asia in 1997 russia in 1998 brazil in 1999 and the speed with which they have spread across countries and regions have called into question the very desirability of financial globalization that is the opening of balance of payments capital accounts in both developed and emerging economies since the mid 1980s 1 calls for a new global financial architecture have multiplied and new and old theoretical arguments for and against controlling capital flows as well as domestic financial markets especially banks have been put forward imf rodrik stiglitz there is little empirical evidence to support the debate over the potential effects of enhanced financial volatility at the sectoral level and especially on the agricultural economy has international financial volatility actually affected real sectoral performance and if so how after briefly reviewing literature in this area this paper introduces the methodology and preliminary results of an on going research project that addresses that question with reference to agricultural commodity trade the purpose of the paper is both to generate productive discussion and to motivate similar research in this

a class of nonlinear arch models a class of nonlinear arch models is suggested the proposed class encompasses several functional forms for arch which have been put forth in the literature a lagrange multiplier test is developed to test engle s arch specification against the wider class of models this test provides an easily computed diagnostic check of the adequacy of an arch model after it has been estimated the theory is applied to a number of weekly exchange rate series and we find strong evidence of nonlinear arch

exchange rate uncertainty and agricultural trade using a sample of bilateral trade flows across ten developed countries between 1974 and 1995 this article explores the effect of exchange rate uncertainty on the growth of agricultural trade as compared to other sectors based on a gravity model that controls for other factors likely to determine bilateral trade the results show that real exchange rate uncertainty has had a significant negative effect on agricultural trade over this period moreover the negative impact of uncertainty on agricultural trade has been more significant compared to other sectors

an explanation for the compass rose pattern abstract the compass rose pattern cannot be observed in daily returns in the spot foreign exchange forex market but is observable when intraday forex returns are used monte carlo simulations show that the pattern is visible only when the tick volatility ratio is above some threshold level a condition that is readily met with intraday returns

exchange rate risk and u s agricultural trade flows this paper analyzes the effect of exchange rate risk on u s agricultural trade flows a model which incorporates exchange rate risk is applied to ten countries while exchange rate risk was not significant in the seven developed markets results indicate that the exchange rate variable adversely affected u s agricultural exports to the three developing countries used in the analysis these findings underscore the importance of exchange rate risk in developing countries trading behavior issues such as establishment of well developed financial and commodity markets in developing countries must be addressed in future research

chaos and the compass rose abstract we show that the recently discovered compass pattern in stock returns that results from discrete jumps of stocks seriously distorts the null distribution of the brock dechert scheinkmann bds chaos test under the null hypothesis of i i d returns the true rejection probability exceeds the nominal size by wide margins which suggests that much of the evidence for chaos that has so far been found in stock returns might well be due to the fact that prices change only in discrete ticks

nonlinear dependence in finnish stock returns abstract past research into the evolution of finnish stock returns focuses on modeling linear and nonlinear dependence using various arima and garch formulations respectively this paper extends the extant work by using grassberger procaccia correlations dimensions to explore the nature of the nonlinear dynamics in daily finnish stock returns during the 1970s and 1980s nonlinear behavior in both periods is evident a simple garch model removes the nonlinearity in the first decade and dramatically reduces the nonlinearity in the second period this supports the notion that finnish stock returns exhibit nonlinear dependence but that the form of dependence is not chaotic

nonlinear dynamics and stock returns simple deterministic systems are capable of generating chaotic output that mimics the output of stochastic systems for this reason algorithms have been developed to distinguish between these two alternatives these algorithms and related statistical tests are also useful in detecting the presence of nonlinear dependence in time series in this article the authors apply these procedures to stock returns and find evidence that indicates the presence of nonlinear dependence on weekly returns from the center for research in security prices value weighted index copyright 1989 by the university of chicago

testing novel implications from the selectorate theory of war the authors tested five novel hypotheses derived from the selectorate theory of war with data for up to about 140 states and spanning the years 1816 1993 the hypotheses point to subtle differences in selection effects across regime types that should operate during crises that fall short of war and also during wars leaders who rely on a large coalition such as democrats to remain in office are shown to be more selective than their small coalition counterparts in their willingness to fight wars when the odds of victory are not overwhelming they are also more selective than their small coalition counterparts in their willingness to take part in disputes that fall short of war when the odds are not exceptionally favorable however they are less selective about this form of participation than they are about war small coalition leaders show no such selectivity in their preparedness to engage in disputes short of war or in war as a function of their odds of victory these results hold whether the odds of victory are assessed continuously or whether they are based on a specific threshold the authors also find in keeping with the selectorate theory that if a war fails to resolve quickly democrats try harder than autocrats to win and when the war is over democrats demobilize much more slowly than autocrats

impact of macroeconomic policies upon agricultural trade and international agricultural development international commodity markets in the early 1980s have experienced a severe cyclical downturn high real rates of interest have discouraged stock holding and disinflation has caused asset market participants to shift out of commodities into financial assets this is only the most recent bout of turbulence since we passed from the stable bliss of the 1950s and 1960s the basic question is whether this instability results from a seemingly unending series of shocks or is there a more general basic explanation which transcends individual events

how sensitive are malaysia s bilateral trade flows to depreciation in an attempt to assess the impact of currency depreciation on the trade balance recent studies are employing disaggregated trade data to avoid aggregation bias however since import and export prices are not available at disaggregated level recent studies are using export and import values rather than their volumes so that they can establish direct relation between inpayments and the exchange rate as well as between outpayments and the exchange rate this study explores the experience of malaysia bilateral inpayments and outpayments models are estimated between malaysia and her 14 trading partners using quarterly data and bound testing approach to cointegration the results show that while real depreciation of the ringgit has short run effects in the long run it increases malaysia s inpayments from only five trading partners

the euro dollar exchange rate chaotic or non chaotic a continuous time model with heterogeneous beliefs abstract the aim of this paper is to develop a continuous time exchange rate model that allows for heterogeneity of the agents beliefs in order to explore non linearities and possible chaotic behaviour the theoretical model contains an intrinsic non linearity that gives rise to a jerk differential equation which is in principle capable of generating chaos the model is econometrically estimated in continuous time with euro dollar data and examined for the possible presence of chaotic motion our results indicate that the possibility of chaotic dynamics in our model is rejected

on nonlinear dynamics the case of the pork cycle new methods for analyzing nonlinear dynamic processes are used to evaluate the hogcorn price ratio the results present evidence of nonlinear dynamics in the pork cycle moreover while garch processes account for some of the nonlinearities the pork cycle is apparently characterized by more complex dynamic forms the empirical analysis provides some evidence of the presence of chaos in the pork cycle the results also indicate that the dynamic process generating the pork cycle is nonlinear and cannot be adequately characterized by a small number of state variables

sectoral effects of exchange rate volatility on united states exports abstract we analyze the effects of real exchange rate volatility on the proportions of bilateral exports of nine categories of goods from the united states to seven major industrial countries using a fixed effect framework in six of the nine categories the volatility of the real exchange rate significantly affects the value of exports and in five of these categories the effect is positive these results are consistent with a model in which risk neutral firms increase supply of elastically demanded exports in response to an increase in the volatility of the real exchange rate

the effects of exchange rate volatility on agricultural trade i extend cho sheldon and mccorriston s 2002 analysis of the effect of exchange rate volatility on agricultural trade among the g 10 countries to a broad sample of developed and developing nations i replicate their original finding that exchange rate volatility has a large negative impact on agricultural trade between g 10 members after controlling for agricultural export subsidies which are correlated with exchange rate volatility i show that the original impact declines by half using the extended sample i find that the effect of exchange rate volatility is much larger for developing country exporters than for developed exporters copyright 2008 oxford university press

the role of price risk in china s agricultural and fisheries exports to the us abstractthis article explores the effect of price risk on the us importers optimal allocation of agriculture imports between the major supplier china and other competing countries we first modify a demand system to account for the impacts of own price risk and cross price risk and then apply the model to 16 agricultural and fisheries commodities exported to the us the estimation results show that importers are sensitive to price risks of 14 chinese commodities comparisons between price risk trade relations of agricultural and fisheries products and between trade effects of cross price risk on chinese goods and substitutes provide strong evidence for explaining the observed trade patterns our study highlights the importance of price stability in promoting international trade especially from developing countries to developed countries

pairs selection and outranking an application to the s p 100 index pairs trading is a popular quantitative speculation strategy this article proposes a general and flexible framework for pairs selection the method uses multiple return forecasts based on bivariate information sets and multi criteria decision techniques our approach can be seen as a sort of forecast combination but the output of the method is a ranking it helps to detect potentially under and overvalued stocks a first application with s p 100 index stocks provides promising results in terms of excess return and directional forecasting

monetary policy real exchange rates and u s agricultural exports interest rates will attract capital to dollar money market instruments which in turn will cause the value of the dollar to rise in foreign exchange markets a stronger dollar makes our exports more expensive to other countries thereby reducing the quantity demanded and it also causes the price of imports into the united states to decline in dollar terms creating competitive pressures for domestic imports sic that compete with imports such as the automobile steel and textile industries the monetary authorities accomplish what they want to accomplish but the burden of adjustment is borne by the export sectors and the sectors that have strong import competition in this way one can see that the problems of agriculture and the automobile industry in the early 1980 s have been cut in part from the same cloth a period of very tight monetary policy

visibility of the compass rose in financial asset returns a quantitative study abstract the compass rose phenomenon is studied based on the random walk model of stock prices it is found that the structure is inherently present in any financial data having a finite precision but becomes visible only under some conditions a quantitative description of the pattern visibility condition is given providing a method for the interpretation of pattern appearance and a more comprehensive understanding of the compass rose phenomenon this is achieved by defining a measure of pattern quality the arguments and the proposed method are supported by numerical examples one such example is the presentation of patterns in portfolios with some specific weights

a panel bootstrap cointegration test this paper proposes a bootstrap test for the null hypothesis of cointegration in panel data the test is general enough to allow for dependence both within and between the cross sectional units and is shown to work well in small samples

interrelationships between monetary instruments and agricultural commodity trade during the last decade agricultural economists have devoted increasing attention to the macroeconomic aspects of agricultural problems indeed a recent presidential address to the american agricultural economics association tweeten centered on the macroeconomics of agriculture given the currency of the monetary approach to macroeconomics it is not surprising therefore that there is also a growing interest in the effects of monetary instruments and monetary phenomena on agricultural commodity trade in this paper i shall discuss what i feel are some of the most pertinent issues that researchers must address in this area before we proceed too far with our discussion it is important to define what i mean by a monetary instrument perhaps arbitrarily i reserve the term monetary instrument for those macroeconomic variables which are primarily determined within domestic or international monetary markets obvious examples are the level of the money supply interest rates and exchange rates i justify the term instrument by noting that as far as the agricultural sector is concerned these variables are by and large predetermined for example the levels of the money supply and interest rates in the united states are to a large extent determined by the policy of the federal reserve similarly the price of the currency the exchange rateis ultimately determined by the demand and the supply for the currency and thus at least partially by governmental policy the first step in any attempt to outline research needs and goals is an identification of what has been done in the past although the literature on the macroeconomics of agriculture is farily large and rapidly expanding eckstein and heien lamm schuh 1976 and tweeten are important examples relatively li tl attention has been given to the effect of monetary instruments on agricultural trade what attention has been given to this area of resea ch has revolved mainly around the role of exchange rates in determining agricultural exports and prices thus it is logical to start our discussion with a brief survey of the literature on exchange rates and agriculture

exchange rate dynamics central bank interventions and chaos control methods abstract we use a simple chartist fundamentalist model developed by day and huang to explore recent chaos control algorithms as potential candidates for central bank intervention rules we find that methods such as delayed feedback control ogy and constant feedback have in principle the potential to reduce exchange rate variability and deviations from fundamentals even in the presence of large dynamic noise

chaotic dynamics in a cash in advance economy abstract this paper introduces sufficient conditions for the existence of deterministic cycles and chaos in cash in advance models building on the earlier work of woodford 1994 chaotic equilibria are shown to be particularly likely in the cash in advance model because of a unique characteristic of such models a discontinuous derivative in the difference equation map at the satiation level of real balances the existence of a kink means that chaotic equilibria may exist without implausibly large curvatures in the utility function since a chaotic time series that makes use of the kink would sometimes exhibit zero nominal interest rates the paper also gives an example of chaos in which nominal interest rates remain strictly positive

stabilization policy can lead to chaos stabilization policy can lead to chaos nonlinearities in economies as elsewhere can generate chaotic equilibria the presence of pareto inferior chaotic equilibria might seem reason enough to use stabilization policy to select preferable equilibria however i show that a stabilization policy with feedback can itself lead to chaotic dynamics thus the existence of nonlinearities in the economy does not by itself justify monetary or fiscal policies aimed at reducing economic instability current evidence cannot distinguish whether monetary policy stabilizes a nonlinear economy creates nonlinear dynamics in the economy or both i introduction in recent years the claim has been made that nonlinearities and self fulfilling expectations in the private economy generate economic instability that can and should be offset by government policies this instability shows up as a positive variance in the steady state of an economy that otherwise would have a steady state with zero variance and higher utility for households on the basis of such models grandmont and malgrange 1986 9 conclude that we should expect a free market economy to perform rather badly under laissez faire in addition there is a possible role for deterministic stabilization policies that would if understood and believed eliminate forecasting mistakes and the corresponding efficiency losses and would guarantee the ultimate disappearance of endogenous fluctuations the purpose of this note is to provide a simple example of stabilization policy leading to chaotic time series behavior this example is an elaboration of friedman s 1953 classic argument that with uncertain knowledge about the economy stabilization policy can increase the variance of the goal variable nonlinearities can make as much a case against stabilization policy as for it the example is ad hoc in some respects but it is based on common ingredients of many models ii a simple example interesting aspects of an economy can be summarized by the quantity equation 1 mv y assume that real income y is constant which implies that changes in nominal income are proportional to changes in the price level in one respect using the quantity equation means that the example below does not have the same force as a tight general equilibrium model of the economy without the underlying detail equation 1 is ad hoc in another respect the example below has more force an equation such as 1 commonly characterizes the general equilibrium models in which money has a significant effect on the economy hence one interpretation is that the example has some generality assume that the monetary authority targets nominal income and knows 1 that the quantity theory characterizes the long run equilibrium of the economy and 2 the level of velocity that is consistent with zero inflation v in these circumstances there is one obvious equilibrium consistent with the goal the money stock is constant and the public expects a constant money supply and zero inflation in this equilibrium nominal income can be stabilized at the target level of nominal income y the monetary authority just need set the money supply to m v 1y if the monetary authority is uncertain about the public s response to its actions one strategy is to adopt a cautious stabilization policy to support the economy s approach to the long run deterministic equilibrium one commonly proposed set of feedback rules is the proportional policies introduced by phillips 1954 in the levels such a rule for the money supply is 2 m m alpha y y sub 1 where y sub 1 is last period s nominal income and alpha is the adjustment parameter assume that private agents believe that the monetary authority eventually will accomplish its goal of setting y equal to y

cointegration and detectable linear and nonlinear causality analysis using the london metal exchange lead contract this study applies linear and nonlinear granger causality tests to examine the dynamic relation between london metal exchange lme cash prices and three possible predictors the analysis uses matched quarterly inventory uk treasury bill interest rates futures prices and cash prices for the commodity lead traded on the lme the effects of cointegration on both linear and nonlinear granger causality tests is also examined when cointegration is not modelled evidence is found of both linear and nonlinear causality between cash prices and analysed predictor variables however after controlling for cointegration evidence of significant nonlinear causality is no longer found these results contribute to the empirical literature on commodity price forecasting by highlighting the relationship between cointegration and detectable linear and nonlinear causality the importance of interest rate and inventory as well as futures price in forecasting cash prices is also illustrated failure to detect significant

non linear granger causality in the currency futures returns abstract this paper examines the relationship between currency futures returns by employing a test for non linear causality the results indicate evidence of unidirectional non linear causality relationship in four cases however after filtering the returns using a garch 1 1 model we find insignificant and statistically weaker non linear causality relationships

effects of exchange rate changes on u s agriculture a dynamic analysis an econometric model of the wheat corn and soybean markets is used to examine the dynamic effects of exchange rate fluctuation on u s commodity markets exports and agricultural prices are found to be sensitive to movements in the exchange rate while domestic factors such as disappearance and inventories are less sensitive but still responsive dramatic short run adjustments in prices and exports are followed by less dramatic but significant longer run adjustments thus the hypothesis of elastic response to the exchange rate seems particularly relevant for the short run

on the power of macroeconomic linkages to explain events in u s agriculture the significance for agriculture of macroeconomic events in the 1980s depends upon what elements in the macroeconomy are most strongly linked to agriculture and how these linkages function it is idle to say for example that inflation poses particularly serious problems for agriculture in the 1980s unless we have evidence that inflation generally causes particularly serious problems for agriculture this paper concentrates on the past literature and current state of evidence on such questions the final section considers the possibility of scientifically defensible forecasts for the 1980s it is short

some evidence concerning macroeconomic chaos abstract an empirical assessment of a linear stochastic perspective for canadian macroeconomic time series is presented the methods used are based on the mathematics of chaos present evidence suggests that low order deterministic chaos does not provide a satisfactory characterization of the data the absence of significant nonlinear structure for the investment and unemployment series is of particular note in light of past findings with american data the degree to which the use of a time trend can impose a pseudo structure on the data is illustrated

exchange rate uncertainty and the demand for u s soybeans this study examines the effects of exchange rate uncertainty on bilateral soybean trade flows and finds that imports for japan france and spain are sensitive to short term variations in nominal bilateral exchange rates this research extends previous work by focusing on bilateral trade for a single commodity using a longer sample period and testing over a variety of model specifications the results suggest that the effects vary across countries depending on access to forward markets the availability of alternative soybean suppliers the degree of market concentration in the domestic soybean processing sector and the degree of currency risk importers are willing to assume the decline in u s agricultural exports during the 1980s has been explained by numerous factors including stagnant world income increased foreign competition the existence of trade barriers and the level of the exchange rate an additional factor exchange rate volatility has received less attention in agricultural trade models since the adoption of the flexible exchange rate system in the early 1970s variability in exchange rates has had a potentially destabilizing impact on trade disruptions in trade can occur because exchange rate variations change the actual price paid or received for traded goods causing adjustments in quantities traded domestic prices or in the timing of sales in order to avoid the effects of variability on profits other longer term effects may occur if exchange rate uncertainty persists to the extent that goods are substitutable such adjustments can be manifested as a sustained preference for domestic suppliers over foreign suppliers or alternative sources of foreign supply may be explored the magnitude of the effect of exchange rate uncertainty on quantity imported is dependent upon inter alia the respective exchange rate elasticities and the importer s response to variability for some goods this magnitude can be substantial the objective of this study is to determine

robust structure without predictability the compass rose pattern of the stock market plotting daily stock returns against themselves with one day s lag reveals a striking pattern evenly spaced lines radiate from the origin the thickest lines point in the major directions of the compass this compass rose pattern appears in every stock it is caused by discreteness however counter examples demonstrate that the existence of exchange imposed tick sizes e g eighths is neither necessary nor sufficient for the compass rose the compass rose cannot be used to make abnormal profits it is structure without predictability among other consequences the compass rose may bias estimation of arch models and tests for chaos technical analysts attempt to identify recurring patterns in stock prices e g edwards and magee 1992 similarly chaos researchers embed time series of stock returns into multi dimensional spaces and attempt to identify lowdimensional attractors e g barnett and chen 1988 figure 1 the hope is that with structure comes predictability and abnormal profits in fact neither of these literatures has yet discovered indisputable structure we follow a procedure similar to a chaos researcher s we look at a simple scatter diagram of daily stock returns plotted against themselves with one day s lag we document a structural relationship the compass rose that is strikingly geometrical in contrast to the products of technical analysis and chaos theory the structure we find is indisputably present in every stock unfortunately the compass rose cannot be used for predictive purposes by market participants it is an artifact of market microstructure it follows that even a successful search for significant structure in stock market data need not enhance predictability nor lead to abnormal profits an equally important lesson is that microstructure effects can be spectacular in daily and even weekly data several areas for future research are given these include potential biases caused by the compass rose in the estimation of autoregressive conditional heteroskedasticity arch models and in a standard test for chaos

regime type the fate of leaders and war we propose and test a formal model of war and domestic politics building on recent evidence on the relationship between regime type the effect of war on the probability of losing office and the consequences of losing office the less the outcome of international interaction affects a leader s tenure and the less punitive are the consequences of losing office the more a leader is willing to make concessions to strike a peaceful bargain we demonstrate that our theory successfully predicts war involvement among nondemocratic regime types moreover our theory offers an intuitive explanation for the democratic peace compared to nondemocratic leaders the tenure of democratic leaders depends relatively little on the war outcome and democratic leaders fare relatively well after losing office thus democratic leaders should be more willing and able to avoid war especially with other democrats

some empirical evidence on the time series properties of four uk asset prices in this paper the authors examine the time series behavior of four u k asset prices and estimate two types of models for the differenced series much previous research has found the presence of time varying heteroskedasticity in the error process for asset prices a linear model with gqarch errors is compared to a joint bilinear model with gqarch errors the latter choice motivated by the ability of bilinear models to capture turbulent behavior the adequacy of these models is determined by examining simulations and also employing test statistics the forecasting performance of the two models is also compared copyright 1996 by the london school of economics and political science