learning to believe in sunspots a number of authors have shown that competitive economies may possess sunspot equilibria that is rational expectations equilibria in which purely extrinsic uncertainty affects equilibrium prices and allocations 2 such results demonstrate that it does not require a lack of faith in the rationality of market participants to believe that competitive markets may be subject to purely speculative fluctuations driven solely by expectations 3 the mere existence of sunspot equilibria as solutions to a system of marketclearing conditions however might not be judged sufficient to indicate that competitive markets with rational participants could ever be subject to speculative instability the sunspot equilibria represent states of affairs in which agents act differently in the case of different realizations of the sunspot variable and it is rational for each agent to do so but it might be thought unlikely that the beliefs of all the participants in the market could ever come to be coordinated so as to bring about an equilibrium of that kind it is rational to believe that sunspots convey information about future states of affairs once the economy is in a sunspot equilibrium but why would rational agents ever begin to believe in such a thing so as to create the conditions under which the belief is rational in order to address such a question one must go beyond the mere statement of the conditions for equilibrium and discussion of what states of affairs satisfy them one must specify an explicit dynamic process according to which the beliefs of agents adjust when out of equilibrium any exercise of this kind is necessarily unsatisfactory as there is no univocal meaning for the postulate of rational behavior outside of an equilibrium it may well be the case that

monetary policy and uncertainty in an empirical small open economy model this paper explores optimal policy design in an estimated model of three small open economies australia canada and new zealand within a class of generalized taylor rules we show that to stabilize a weighted objective of output consumer price in ation and nominal interest variation optimal policy does not respond to the nominal exchange this is despite the presence of local currency pricing and due in large part to observed exchange rate disconnect in these economies optimal policies that account for the uncertainty of model estimates as captured by the parameters posterior distrbution similarly exhibit a lack of exchange rate response in contrast to brainard 1967 the presence of parameter uncertainty can lead to more or less aggressive policy responses depending on the model at hand

comparing four models of aggregate fluctuations due to self fulfilling expectations abstract this paper compares four equilibrium business cycle models with increasing returns to scale production technologies that allow for aggregate fluctuations due to self fulfilling expectations necessary and sufficient conditions for the existence of stationary sunspot equilibria are derived numerical examples demonstrate that the degree of increasing returns necessary for the existence of stationary sunspot equilibria lies in the upper range of available empirical estimates the paper also shows that persistent fluctuations are not a necessary property of these four models when the only source of fluctuations is changes in people s expectations about the future path of the economy journal of economic literature classification numbers e32 d43

testing for indeterminacy an application to u s monetary policy reply this paper considers a prototypical new keynesian model in which the equilibrium is undetermined if monetary policy is passive the likelihood based estimation of dynamic equilibrium models is extended to allow for indeterminacies and sunspot fluctuations we construct posterior weights for the determinacy and indeterminacy region of the parameter space and estimates for the propagation of fundamental and sunspot shocks according to the estimated model u s monetary policy post 1982 is consistent with determinacy whereas the pre volcker policy is not we find that before 1979 indeterminacy substantially altered the propagation of shocks

current real business cycle theories and aggregate labor market fluctuations hours worked and the return to working are weakly correlated traditionally the ability to account for this fact has been a litmus test for macroeconomic models existing real business cycle models fail this test dramatically we modify prototypical real business cycle models by allowing government consumption shocks to influence labor market dynamics this modification can in principle bring the models into closer conformity with the data our empirical results indicate that it does

price stability with imperfect financial integration this paper studies whether the international monetary system can be affected by asymmetries in the cross country positions in the international financial markets i e the fact that some countries are large debtors while others are creditors an important channel that is explored is the interaction between international risk sharing and the stabilization role of monetary policy in each country the main finding is that the welfare costs of incomplete markets and the gains of deviating from a policy of price stability are increasing with the cross country asymmetries in the initial net international positions and in particular they become nonnegligible when the persistence of the shocks increases 1 of a permanent shift in steady state consumption for the welfare costs of incomplete markets and 0 2 for the gains of deviating from a policy of price stability when global imbalances become larger optimal monetary policy requires an increase in the volatilities of the real returns on assets and in particular of the nominal interest rates which should happen to be more correlated across countries

indeterminacy under constant returns to scale in multisector economies recently there has been a renewed interest in indeterminacy or alternatively put in the existence of a continuum of equilibria in dynamic economies that exhibit some market imperfections one of the primary concerns of this literature has been the empirical plausibility of indeterminacy which arises in markets with external effects or with monopolistic competition often coupled with some degree 10 of increasing returns

chaos significance mechanism and economic applications imagine a bargaining model say involving diplomats negotiating tariff levels or a disarmament treaty in which each party has been instructed by higher headquarters to respond to each new offer by her opposite number with a counteroffer that is to be calculated from a simple reaction function provided in advance both negotiating parties are prohibited from revealing their own reaction functions to the other if the perfectly deterministic sequence of offers and counteroffers that must emerge from these simple rules were to begin to oscillate wildly and apparently at random the negotiations could easily break down as each party not understanding the source of the problem came to suspect the other side of duplicity and sabotage yet all that may be involved as we will see is the phenomenon referred to as chaos a case that is emphatically not pathological but in which a dynamic mechanism that is very simple and deterministic yields a time path so complicated that it will pass most standard tests of randomness chaos has become a subject of great interest to specialists and nonspecialists alike besides economics it has entered the literature of geometry physics ecology and meteorology it has been written about at length in the new york times magazine and scientific american as well as technical publications this article seeks to describe what it is how it works and what it means for economics

automobile insurance ratemaking in the presence of asymmetrical information automobile insurance is an example of a market where multi period contracts are observed this form of contract can be justified by asymmetrical information between the insurer and the insured insurers use risk classification together with bonus malus systems in this paper we show that the actual methodology for the integration of these two approaches can lead to inconsistencies we develop a statistical model that adequately integrates risk classification and experience rating for this purpose we present poisson and negative binomial models with regression component in order to use all available information in the estimation of accident distribution a bonus malus system which integrates a priori and a posteriori information on an individual basis is proposed and insurance premium tables are derived as a function of time past accidents and the significant variables in the regression statistical results were obtained from a sample of 19 013 drivers

capacity utilization under increasing returns to scale abstract this paper overcomes an important objection against the empirical relevance of the benhabib farmer model as a potential account of actual business cycle fluctuations this is attributable to an elasticity effect and a returns to scale effect of capacity utilization these effects are closely related to the empirical puzzles that capital appears to play an insignificant role in explaining cyclical movements in output and that the estimated labor elasticity appears to be larger than labor s share due to these effects multiple equilibria and persistent fluctuations can easily occur in a growth model for externalities mild enough so that the aggregate labor demand curve is downward sloping analyses show that the propagation mechanism generated by capacity utilization under mild increasing returns is capable of explaining the periodic patterns of u s business cycles documented by watson journal of economic literature classification numbers e32 e22 c52

risk overhang and market behavior we show that exposure from past business transactions risk overhang can reduce activity in related business lines sometimes to the point where no new trade occurs we focus primarily on the role of overhang in nonlife insurance market disruptions our model predicts that the relative impact duration and character of supply disruptions are related to the extent of overhang these predictions are consistent with differences between the mid 1980s liability insurance crisis and the early 1990s catastrophe reinsurance crisis the overhang model predicts attributes of these crises that prior explanations relying on adverse selection do not we also discuss applications of the overhang model to disruptions in lending and securities markets

iterative computation of cournot equilibrium abstract in a homogeneous coumot model with quasi concave profit functions the problem of determining an equilibrium can be posed as one of solving an equation in one real variable total sales if the response functions are monotone or firms are identical then a certain iterative process based on averaging converges to an equilibrium such iterations have the interpretation that every firm responds to the average of sales by other firms in brevious periods

selection dynamics asymptotic stability and adaptive behavior selection dynamics are often used to distinguish stable and unstable equilibria this is particularly useful when multiple equilibria prevent a priori comparative static analysis this paper reports an experiment designed to compare the accuracy of the myopic best response dynamic and an inertial selection dynamic the inertial selection dynamic makes more accurate predictions about the observed mutual best response outcomes

the value of screening mechanisms under alternative insurance possibilities abstract this paper investigates the welfare implications of symmetrical improvements in information and accompanying screening mechanisms which allow for improved matching of individuals to their respective risk classes unlike previous models used to investigate this phenomenon this paper allows for the possibility that individuals differ not simply according to exogenously specified unequal loss probabilities but rather that individuals possess different self protection technologies moreover various insurance contracting possibilities are also considered it is demonstrated that the structural form of the heterogeneity of technologies and the type of insurance contracts available in the market determine in an interactive way the value of information which improves the matching of individuals to risk class

categorizing risks in the insurance industry this paper analyzes the welfare implications of imperfectly categorizing risks in the insurance industry under conditions of asymmetric information firms initially unable to distinguish the risk type of individuals are provided with imperfect information concerning risk membership the paper then compares various wilson type equilibria to determine the welfare implications of firms imperfectly categorizing risks it is shown that only in the case where the initial equilibrium is of the nash no subsidy type is there a pareto type improvement in welfare

indeterminacy home production and the business cycle a calibrated analysis abstract in this paper i present a business cycle model with one market sector that produces a standard good and another that produces a non market or home good the model can have multiple equilibria and therefore cycles driven only by self fulfilling expectations with low externalities to market production in particular an upward sloping aggregate labor demand as e g in farmer and guo j economic theory 63 1994 42 72 is not required for indeterminacy the effect of technology shocks is also studied in all cases the time series that are generated have properties that are comparable to the real us postwar series

spotting sunspots some evidence in support of models with self fulfilling prophecies abstract this paper adds financial assests to roger farmer s business cycle model with increasing returns and self fulfilling beliefs by using information from the financial markets in conjunction with the structure of the model we can uncover from financial data the belief shocks that drive the model specifically we assume that belief shocks drive both economic fluctuations and asset returns the financial market information allows us to identify these shocks we use our methods to generate dynamic simulations of the model and show that it has incremental predictive power for key us time series

evidence on adverse selection equilibrium signaling and cross subsidization in the insurance market the configuration of equilibrium in the market for automobile collision insurance is examined empirically by representing the premium deductible menu and the demand function as a standard hedonic system using contractual data from a representative insurer we estimate a reduced form hedonic premium equation and the inverse of the marginal bid equation for insurance coverage the data reveal an equilibrium with adverse selection and market signaling but lead us to reject the hypothesis that high risks receive contracts subsidized by low risks

aggregate returns to scale and embodied technical change theory and measurement using stock market data abstract we develop a new general equilibrium growth accounting framework that features increasing returns to scale imperfect competition and incorporates technological revolutions into the description of technical progress we propose a way to tell apart revolutionary changes in technology and incremental innovations using stock market data we use our framework to jointly estimate the overall embodied tfp change during 1953 1995 and the aggregate output elasticity we find that the it revolution raised the aggregate tfp level by about 20 we suggest a 1 09 1 11 range for the aggregate returns to scale

adverse selection and finite horizon insurance contracts abstract we use a particular contract to analyze three issues regarding adverse selection monopoly and the use of time within a finite horizon the description and existence of an epsilon equilibrium equilibrium the achievement of a nash equilibrium and the optimality of risk revelation among the results obtained we show that at equilibrium low risk individuals buy full insurance most of the time and high risk individuals always buy full insurance we also show that the equilibrium with risk revelation is a nash equilibrium these results are compared with those of the self selection mechanism stiglitz 1977 and of the equilibrium under moral hazard radner 1981

limited asset markets participation monetary policy and inverted aggregate demand logic abstract this paper incorporates limited asset markets participation in dynamic general equilibrium and develops a simple analytical framework for monetary policy analysis aggregate dynamics and stability properties of an otherwise standard business cycle model depend nonlinearly on the degree of asset market participation while moderate participation rates strengthen the role of monetary policy low enough participation causes an inversion of results dictated by conventional wisdom the slope of the is curve changes sign the taylor principle is inverted optimal welfare maximizing discretionary monetary policy requires a passive policy rule and the effects and propagation of shocks are changed however a targeting rule implementing optimal policy under commitment delivers equilibrium determinacy regardless of the degree of asset market participation our results may justify fed s behavior during the great inflation period

adverse selection and statistical discrimination an analysis of canadian automobile insurance abstract statistical discrimination occurs when a characteristic such as sex is used as an indicator of the risk group of an individual the theory of adverse selection is used to explain the occurrence of statistical discrimination a model of the market for collision insurance which is based on the theory of adverse selection is estimated on canadian data the results suggest that adverse selection occurs in this market simulations of the effect of prohibiting sexual discrimination in the 21 24 age group indicate that the premiums for single females would increase substantially and that a significant proportion would no longer purchase collision insurance

the efficiency effects of categorical discrimination in the insurance industry recent public policy debate has focused concern on the equity dimensions of categorical discrimination based on sex age or race in insurance and similar markets we consider the efficiency effects of such discrimination and establish that costless imperfect categorization always enhances efficiency when categorization entails a nonnegligible resource cost however no unambiguous efficiency ranking of informational regimes is possible when categorization is costless we demonstrate that government having no better information than market participants can effect redistribution without assuming dictatorial control of the market implying that a market equilibrium with costless categorization is potentially pareto superior to one without it when categorization is costly however the market may categorize when pareto improvements are not possible

indeterminacy of equilibria in a hyperinflationary world experimental evidence the authors design and study an olg experimental economy where the government finances a fixed real deficit through seigniorage the economy has continua of nonstationary rational expectations equilibria and two stationary rational expectations equilibria the authors do not observe nonstationary rational expectations paths observed paths tend to converge close to or somewhat below the low inflation stationary state the adaptive learning hypothesis is consistent with the data in selecting the low inflation stationary state rational expectations equilibrium as a long run stationary equilibrium nevertheless simple adaptive learning models do not capture the market uncertainty or the biases observed in the data copyright 1993 by the econometric society

firm dynamics and markup variations implications for sunspot equilibria and endogenous economic fluctuations this paper analyzes how the interaction between firms entry and exit decisions and variations in competition gives rise to self fulfilling expectation driven fluctuations in aggregate economic activity and in measured total factor productivity tfp the analysis is based on a dynamic general equilibrium model in which net business formation is endogenously procyclical and leads to endogenous countercyclical variations in markups this interaction leads to indeterminacy in which economic fluctuations occur as a result of self fulfilling shifts in the beliefs of rational forward looking agents when calibrated with empirically plausible parameter values and driven solely by self fulfilling shocks to expectations the model can quantitatively account for the main empirical regularities characterizing postwar u s business cycles and for 65 of the fluctuations in measured tfp

some unpleasant general equilibrium implications of executive incentive compensation contracts abstract we consider a simple real business cycle model in which shareholders hire self interested executives to manage their firm a generic family of compensation contracts similar to those employed in practice is studied when compensation is convex in the firm s dividend an increase in the firm s output results in a more than proportional increase in the managers income incentive contracts of sufficient yet modest convexity are shown to result in an indeterminate general equilibrium one in which business cycles are driven by self fulfilling fluctuations in managers expectations the proposed family of contracts may yield first best outcomes for specific parameter choices

asymmetric information and learning evidence from the automobile insurance market this paper tests the predictions of adverse selection models using data from the automobile insurance market i find that in contrast to what recent research suggests the evidence is consistent w