the tail index of exchange rate returns in the literature on the empirical distribution of foreign exchange rates there is now consensus that exchange rate yields are fat tailed three problems however persist 1 which class of distribution functions is most appropriate 2 are the parameters of the distribution invariant over subperiods 3 what are the effects of aggregation over time on the distribution in this paper we employ extreme value theory to shed new light on these questions we apply the theoretical results to ems data

parametric recoverability of preferences revealed preference theory is brought to bear on the problem of recovering approximate parametric preferences from consistent and inconsistent consumer choices we propose measures of the incompati

detecting periodically collapsing bubbles a markov switching unit root test this paper addresses the problem of testing for the presence of a stochastic bubble in a time series in the case that the bubble is periodically collapsing so that the asset price keeps returning to the level implied by the market fundamentals as this is essentially a problem of identifying the collapsing periods from the expanding ones we propose using a generalization of the dickey fuller test procedure which makes use of the class of markov regime switching models the potential of the new methodology is illustrated via simulation and an empirical example is given copyright 1999 john wiley sons ltd

entrepreneurs risk aversion and dynamic firms how do entrepreneurs vary firm size capital structure and default to manage risk we show that more risk averse entrepreneurs run smaller more highly leveraged firms and default less because running a smaller firm with higher debt reduces personal funds at risk in the firm optimal default depends on ex ante debt consumption forgone from firm liquidation and owner capacity to inject funds we show that entrepreneurs sacrifice current consumption in the hope of future success that never materializes for the bottom 25 percent but entrepreneurship is a path toward great wealth and high consumption for the top quartile

on the frequency of large stock returns putting booms and busts into perspective textabstractnumerous articles have investigated the distribution of share prices and find that the returns are fat tailed nevertheless there is still controversy about the amount of probability mass in the tails and hence about the most appropriate distribution to use in modeling returns this controversy has proven hard to resolve as the alternatives are non nested we employ extreme value theory focusing exclusively on the larger observations in order to assess the tail shape within a unified framework we find that at least the first two moments exist this enables one to generate robust probabilities on large returns which put the recent stock market swings into historical perspective

garp for kids on the development of rational choice behavior in this paper we examine the extent to which consumption choices by 7 and 11 year old children and college undergraduates satisfy the axioms of revealed preference we find that choices by even the 7 year olds are considerably more likely to obey revealed preference axioms than would be true if they were choosing randomly 11 year olds do better still while college students do no better than 11 year old children we also find that mathematical ability is not correlated with choosing rationally we argue that this evidence suggests that the ability to choose rationally is not innate but that it does develop quickly

the money pump as a measure of revealed preference violations we introduce a measure of the severity of violations of the revealed preference axioms the money pump index mpi the mpi is the amount of money one can extract from a consumer who violates the axioms it is also a statistical test for the hypothesis that a consumer is rational when behavior is observed with error we present an application using a panel data set of food expenditures the data exhibit many violations of the axioms mostly the mpi for these violations is small the mpi indicates that the hypothesis of consumer rationality cannot be rejected

eliciting welfare preferences from behavioural data sets an individual displays various preference orderings in different payoff irrelevant circumstances it is assumed that the variation in the observed preference orderings is the outcome of some cognitive process that distorts the underlying preferences of the individual we introduce a framework for eliciting the individual s underlying preferences in such cases and then demonstrate it for two cognitive processes satisficing and small assessment errors

some evidence of speculative bubbles in the foreign exchange markets the authors propose that the poor performance of portfolio models is due to their exclusion of speculative bubbles they suggest a new unce rtainty bubble solution as opposed to a risk bubble solution discr etion is minimized because the trend of the bubble is an exact functi on of the structural parameters for three exchange rates the bubble augmented portfolio model passes the usual statistical tests and per forms better than its var equivalent in out of sample dynamic simulat ion when the model was reestimated with the bubbles removed and wit h ordinary dummies in place of the constrained trend the parameter e stimates were invariably insignificant copyright 1987 by ohio state university press

on rational bubbles and fat tails this paper addresses the statistical properties of time series driven by rational bubbles a la blanchard and watson 1982 using insights on the behavior of multiplicative stochastic processes we demonstrate that the tails of the unconditional distribution emerging from such bubble processes follow power laws exhibit hyperbolic decline more precisely we find that rational bubbles predict a fat power tail for both the bubble component and price differences with an exponent smaller than 1 the distribution of returns is dominated by the same power law over an extended range of large returns although power law tails are a pervasive feature of empirical data these numerical predictions are in disagreement with the usual empirical estimates it therefore appears that exogenous rational bubbles are hardly reconcilable with some of the stylized facts of financial data at a very elementary level

the handbook of international macroeconomics preface 1 introduction rick van der ploeg amsterdam 2 quantity constrained models of open economies neil rankin warwick 3 imperfect competition and open economy macroeconomics huw d dixon york 4 relative price movements in dynamic general equilibrium models of international trade david backus nyu patrick kehoe pennsylvania and finn kydland carnegie mellon 5 international fiscal policy coordination and competition assaf razin and efraim sadka tel aviv 6 capital taxation in the world economy a lans bovenberg tilburg 7 history of the international monetary system implications for research in international macroeconomics and finance barry eichengreen berkeley 8 on inflation unemployment and the optimal exchange rate regime george alogoskoufis athens 9 macroeconomic policy speculative attacks and balance of payments crisis pierre richard agenor and robert p flood imf 10 continuous time models of exchange rates and intervention giuseppe bertola princeton 11 stylized facts of nominal exchange rate returns casper g de vries leuven 12 partial versus general equilibrium models of international capital market equilibrium 13 sovereign debt kenneth kletzer santa cruz 14 growth and external debt daniel cohen cepremap 15 growth and deficits in an interdependent world index

on testing the utility hypothesis in order to be able to conduct a test of the core utility hypothesis that is not confounded with tests of subsidiary hypotheses that economic agents all have the same preferences and that their preferences are weakly separable it is necessary to use data that are disaggregated and complete in order to carry out a utility hypothesis test with complete data revealed preference theory must first be extended the generalised axiom of revealed preference is extended to include labour supply and portfolio choice then a complete disaggregated data set is used to test the utility hypothesis and two preference separability hypotheses

measuring rationality with the minimum cost of revealed preference violations abstract we introduce a new measure of how close a set of choices is to satisfying the observable implications of rationality and apply it to a large balanced panel of household level consumption data this new measure the minimum cost index is the minimum cost of breaking all revealed preference cycles found in choices from budget sets unlike existing measures of rationality it responds to both the number and severity of revealed preference violations

how demanding is the revealed preference approach to demand a well known problem with revealed preference methods is that when data are found to satisfy their restrictions it is hard to know whether this should be viewed as a triumph for economic theory or a warning that these conditions are so undemanding that almost anything goes this paper allows researchers to make this distinction our approach uses an axiomatic characterization of a measure of predictive success due to selten 1991 we illustrate the idea using a panel dataset the results show that this approach can lead us to radically reassess our view of the empirical performance of economic theory

testing for bubbles in exchange markets a case of sparkling rates this paper investigates the possibility that the observed deviations of major bilateral exchange rates from values implied by market fundamentals are a consequence of rational asset market bubbles when a new econometric methodology for detecting asset market bubbles is used the joint hypothesis of no bubbles and stable autoregressive processes for relative money supplies and real incomes is rejected for the dollar deutsche mark and dollar pound ratesusing monthly data over the period 1973 82 additional tests for coefficient stability and for lack of cointegration between exchange rates and market fundamentals suggest that the bubble findings must be interpreted with care

rational bubbles during poland s hyperinflation implications and empirical evidence abstract it has been argued that the polish hyperinflation at the end of the eighties was too excessive to be attributed to market fundamentals only in this paper a range of indirect non structural and structural tests for rational exploding deterministic and stochastic bubbles are carried out we adopt a new strategy based on the work of hall and sola 1993a which allows for the possibility of switching regimes in the time series properties of the data to allow for both indirect tests and structural tests for the presence of stochastic bubbles

testing data for consistency with revealed preference the author develops a method of hypothesis testing for revealed preference tests this method is particularly well suited to tests of commonality of tastes or tests of preference stability he devises a metric based on an estimate of the fraction of expenditure wasted in maximizing utility if all consumers in the sample share the same utility function this metric increases in size with increases in the proportion of observations having different tastes and with increasing differences in tastes the author proposes bootstrap methods for estimating the distribution of the test statistic copyright 1995 by mit press

a theory of anticipated utility abstract a new theory of cardinal utility with an associated set of axioms is presented it is a generalization of the von neumann morgenstern expected utility theory which permits the analysis of phenomena associated with the distortion of subjective probability

employment stability in newly founded firms a matching approach using linked employer employee data from germany using a linked employer employee dataset and taking the perspective of individuals rather than firms this paper analyzes some effects of joining startups we show that entrants in new firms differ from those joining incumbent firms and we use a matching approach to compare a group of employees joining new firms in 1995 1996 with a control group entering incumbent firms our results indicate that individuals employment stability was higher in incumbent than in newly founded firms while their risk of becoming unemployed was lower in particular in eastern germany joining firms that were older than 6 years improved individuals employment prospects

a test for speculative bubbles in the sterling dollar exchange rate 1981 84 the u s dollar price of the u k pound sterling is tested for a speculative bubble defined as a period with a nonzero median in excessreturns a nonparametric procedure is developed which controls for data mining over the period of flexible exchange rates and finds a negative bubble in the excess return to holding sterling rather than dollar assets during the period 1981 84 possible interpretations arebootstrap equilibria rational bubbles nonsym metric fundamentals and nonrational expectations copyright 1986 by american economic association

a measure of rationality and welfare evidence showing that individual behavior often deviates from the classical principle of preference maximization has raised at least two important questions 1 how serious are the deviations 2 what is the best way to analyze choice behavior in order to extract information for the purpose of welfare analysis this paper addresses these questions by proposing a new way to identify the preference relation that is closest in terms of welfare loss to the revealed choice

borrowing from employees wage dynamics with financial constraints we analyze how the financial conditions of the firm affect the compensation structure of workers the size of the firm and its dynamics firms that are financially constrained offer long term wage contracts characterized by an increasing wage profile that is they pay lower wages today in exchange of higher future wages effectively borrowing from their employees because constrained firms also operate at a suboptimal scale which then increases gradually over time we have that younger and smaller firms grow faster and pay lower wages jel g31 j31 e24

optimal lending contracts and firm dynamics we develop a general model of lending in the presence of endogenous borrowing constraints borrowing constraints arise because borrowers face limited liability and debt repayment cannot be perfectly enforced in the model the dynamics of debt are closely linked with the dynamics of borrowing constraints in fact borrowing constraints must satisfy a dynamic consistency requirement the value of outstanding debt restricts current access to short term capital but is itself determined by future access to credit this dynamic consistency is not guaranteed in models of exogenous borrowing constraints where the ability to raise short term capital is limited by some prespecified function of debt we characterize the optimal default free contract which minimizes borrowing constraints at all histories and derive implications for firm growth survival leverage and debt maturity the model is qualitatively consistent with stylized facts on the growth and survival of firms comparative statics with respect to technology and default constraints are derived borrowing constraints are an important determinant of firm growth and survival 1 such constraints may arise in connection to the financing of investment opportunities faced by firms or temporary liquidity needs such as those required to survive a recession this paper develops a theory of endogenous borrowing constraints and studies its implications for firm dynamics in our model debt is constrained by the firm s limited liability and option to default a lending contract specifies an initial loan size future financing and a repayment schedule the choice of these variables in turn determines future growth the firm s future borrowing capacity and its ability and willingness to repay hence borrowing constraints and firm dynamics are jointly determined we study this dynamic design problem our model builds on thomas and worral s 1994 model of foreign direct investment at time zero a risk neutral borrower firm or entrepreneur has a project which requires a fixed initial set up cost every period the project yields revenues that increase with the amount of 1 there is considerable evidence suggesting that financing constraints are important determinants of firm dynamics gertler and gilchrist 1994 argue that liquidity constraints may explain why small manufacturing firms respond more to a tightening of monetary policy than do larger manufacturing firms perez quiros and timmermann 2000 show that in recessions smaller firms are more sensitive to the worsening of credit market conditions as measured by higher interest rates and default premia evans and jovanovic 1989 show that the liquidity constraints are essential in the decision to become an entrepreneur fazzari hubbard and petersen 1988 among others view financial constraints as an explanation for the dynamic behaviour of aggregate investment and cabral and mata 1996 are able to fit reasonably well the size distribution of portuguese manufacturing firms by estimating a simple model of financing constraints for surveys see hubbard 1998 and stein 2003

nonparametric tests of utility maximization and weak separability for consumption leisure and money some of the most fundamental assumptions of economics are utility maximization and weak separability of the arguments in the represen tative consumer s utility function this paper contains results from nonparametric tests of these assumptions about consumer behavior the authors find that quarterly per capita data on consumption goods le isure and monetary assets are consistent with utility maximization further consumption goods and leisure meet necessary and sufficient conditions for weak separability additionally one grouping of relat ively liquid monetary assets meets the necessary conditions for weak separability they also test and find no evidence of homothetic prefe rences copyright 1987 by mit press

consistency and heterogeneity of individual behavior under uncertainty by using graphical representations of simple portfolio choice problems we generate a very rich dataset to study behavior under uncertainty at the level of the individual subject we test the data for consistency with the maximization hypothesis and we estimate preferences using a two parameter utility function based on faruk gul 1991 this specification provides a good interpretation of the data at the individual level and can account for the highly heterogeneous behaviors observed in the laboratory the parameter estimates jointly describe attitudes toward risk and allow us to characterize the distribution of risk preferences in the population

fundamentals uncertainty bubbles and exchange rate dynamics abstract using a monetary model of exchange rate determination we study exchange rate dynamics with bubbles which depend on stochastic market fundamentals these dynamics can be either stochastically stable or unstable and either monotonic or non monotonic including cyclic in an extreme case they converge with probability one and exhibit cyclic movements implications for the analysis of time dependent regime shifts are also explored exchange rates with bubbles are likely to appear less volatile than the fundamentals in finite samples both the variance bounds and cointegration tests might thus be ineffective in testing the absence of bubbles under fundamentals uncertainty

pitfalls in testing for explosive bubbles in asset prices a number of studies e g robert j shiller 1981 olivier j blanchard and mark watson 1982 kenneth d west 1988 have argued that dividend and stock price data are not consistent with the market fundamentals hypothesis in which prices are given by the present discounted values of expected dividends these results have often been construed as evidence for the existence of bubbles or fads related arguments have been made with respect to gold bonds and foreign exchange a major problem with such arguments e g james hamilton and charles whiteman 1985 is that apparent evidence for bubbles can be reinterpreted in terms of market fundamentals that are unobserved by the researcher behzad t diba and herschel i grossman 1984 1988b and hamilton and whiteman 1985 have recommended the alternative strategy of testing for rational bubbles by investigating the stationarity properties of asset prices and observable fundamentals 1 in essence the argument for equities is that if stock prices are not more explosive than dividends then it can be concluded that rational bubbles are not present since they would generate an explosive component to stock prices 2 using unit root tests autocorrelation patterns and cointegration tests to implement this procedure diba and grossman 1988b p 529 state that the analysis supports the conclusion that stock prices do not contain explosive rational bubbles this paper shows that the above battery of tests is in fact unable to detect an important class of rational bubbles the point is demonstrated by constructing rational bubbles that appear to be stationary when unitroot tests are applied even though they are explosive in the relevant sense simulations show that when such bubbles are present stock prices will not appear to be more explosive than dividends on the basis of these tests even though the bubbles are substantial in magnitude and volatility the presence of rational bubbles in actual stock prices thus remains an open question