the impact of fat tails on equilibrium rates of return and term premia abstract we investigate the impact of ignoring fat tails observed in the empirical distributions of macroeconomic time series on the equilibrium implications of the consumption based asset pricing model with habit formation fat tails in the empirical distributions of consumption growth rates are modeled as a dampened power law process that nevertheless guarantees finiteness of moments of all orders this renders model implied mean equilibrium rates of return and equity and term premia finite comparison with a benchmark gaussian process reveals that accounting for fat tails lowers the model implied mean risk free rate by 20 percent raises the mean equity premium by 80 percent and the term premium by 20 percent bringing the model implications closer to their empirically observed counterparts fat tails also increase the model implied volatility of the risk free rate and the equity premium

a multiobjective approach to vendor selection abstract purchases from vendors involve significant costs for many firms decisions related to these purchases include the selection of vendors and the determination of order quantities to be placed with the selected vendors such decisions are frequently multiobjective in nature that is they are evaluated by more than one criterion at least 23 criteria for various vendor selection problems have been identified in this article we present a multiobjective approach to systematically analyze the inherent tradeoffs involved in multicriteria vendor selection problems the approach is motivated by and demonstrated with an actual purchasing problem facing a division of a fortune 500 company

review essay on charles f manski s public policy in an uncertain world analysis and decisions public policy setting often involves quantitative choices with quantitative outcomes yet unqualified statements about the precise consequences of alternative choices characterize much of the policy analysis bearing on these decisions public policy in an uncertain world analysis and decisions by charles f manski characterizes and richly illustrates the nature of this unwarranted certitude it details specific constructive alternatives on which the economics profession has achieved varying degrees of consensus those in our profession charged with the education of future policy analysts should consider using it and how to round out its presentation of decision making from their own perspective jel d02 d04 d80 e61

reversing disbursement rates to estimate stationary wealth processes for endowments with recursive preferences endowments have been accused of hoarding their wealth however the theoretically ideal spending plan remains unclear and in practice endowments follow a range of rules here we derive and estimate the optimal spending plans of an infinitely lived charity or endowment with an epstein zin weil utility function given general markovian returns to wealth we analyse two special cases first where spending is a power function of last period s wealth and second where the endowment uses payout smoothing via non linear least squares we estimate the optimal spending rate and the elasticity of inter temporal substitution for an endowment with a typical diversified portfolio and for a portfolio of hedge funds in a new approach we use maximum entropy methods to characterize the returns distribution of an endowment whose spending plan conforms with the optimality condition we confirm that the estimated returns distribution is largely consistent with the optimal spending plan

unforeseen contingencies and incomplete contracts we scrutinize the conceptual framework commonly used in the incomplete contract literature this literature usually assumes that contractual incompleteness is due to the transaction costs of describing or of even foreseeing the possible states of nature in advance we argue however that such transaction costs need not interfere with optimal contracting i e transaction costs need not be relevant provided that agents can probabilistically forecast their possible future payoffs even if other aspects of the state of the nature cannot be forecast in other words all that is required for optimality is that agents be able to perform dynamic programming an assumption always invoked by the incomplete contract literature the foregoing optimality result holds very generally provided that parties can commit themselves not to renegotiate moreover we point out that renegotiation may be hard to reconcile with a framework that otherwise presumes perfect rationality however even if renegotiation is allowed the result still remains valid provided that parties are risk averse

on welfare frameworks and catastrophic climate risks recent theoretical work in the economics of climate change has suggested that climate policy is highly sensitive to fat tailed risks of catastrophic outcomes weitzman 2009 68 such risks are suggested to be an inevitable consequence of scientific uncertainty about the effects of increased greenhouse gas concentrations on climate criticisms of this controversial result fall into three categories the first suggests that it may be irrelevant to cost benefit analysis of climate policy the second challenges the fat tails assumption and the third questions the behavior of the utility function assumed in the result this paper analyses these critiques and suggests that those in the first two categories have formal validity but that they apply only to the restricted setup of the original result which may be extended to address their concerns they are thus ultimately unconvincing critiques in the third category are shown to be robust however they open up new ethical and empirical challenges for climate economics that have thus far been neglected how should we value catastrophes as a society i demonstrate that applying results from social choice to this problem can lead to counterintuitive results in which society values catastrophes as infinitely bad even though each individual s utility function is bounded finally i suggest that the welfare functions traditionally used in climate economics are ill equipped to deal with climate catastrophes in which population size changes drawing on recent work in population ethics i propose an alternative welfare framework with normatively desirable properties which has the effect of dampening the contribution of catastrophes to welfare

solving asset pricing models when the price dividend function is analytic we present a new method for solving asset pricing models which yields an analytic price dividend function of one state variable to illustrate our method we give a detailed analysis of abel s asset pricing model a function is analytic in an open interval if it can be represented as a convergent power series near every point of that interval in addition to allowing us to solve for the exact equilibrium price dividend function the analyticity property also lets us assess the accuracy of any numerical solution procedure used in the asset pricing literature

a theory of firm scope the formal literature on firm boundaries has assumed that ex post conflicts are resolved through bargaining in reality parties often simply exercise their decision rights we develop a model based on shading in which the use of authority has a central role we consider two firms deciding whether to adopt a common standard nonintegrated firms may fail to coordinate if one firm loses an integrated firm can internalize the externality but puts insufficient weight on employee benefits we use our approach to understand why cisco acquired stratacom a provider of new transmission technology we also analyze delegation

the reference point approach to the theory of the firm an introduction there is a small but growing literature on the reference point approach to incomplete contracts as formulated by hart and moore the reference point approach has begun to be applied to the theory of the firm in 3 recent papers this introduction reviews the main theoretical aspects of each of these papers it then discusses the relationship between the reference point approach to the firm the transaction cost approach and the property rights approach here it is argued that the reference point approach is a step back towards ex post inefficiencies away from reliance on ex ante inefficiencies

multiattribute utility analysis the case of filipino rice policy major uncertainties and conflicting objectives often arise in public policy analysis this paper advances a framework that is appropriate for public policy problems frequently encountered in agriculture and food systems among other possible benefits its principal value is to provide focus on the major conflicts trade offs and subjective perceptions among affected groups it can be used to isolate major disagreements needed empirical evidence appropriate degrees of risk aversion equity value judgments and consensus solutions in an empirical setting the framework is used to evaluate price policy for rice in the philippines

relational contracts and the theory of the firm relational contracts informal agreements sustained by the value of future relationships are prevalent within and between firms we develop repeated game models showing why and how relational contracts within firms vertical integration differ from those between nonintegration we show that integration affects the parties temptations to renege on a given relational contract and hence affects the best relational contract the parties can sustain in this sense the integration decision can be an instrument in the service of the parties relationship our approach also has implications for joint ventures alliances and networks and for the role of management within and between firms

surveying the economics of plural modes of organization why do firms concomitantly rely on more than one organizational arrangement to procure distribute a given input product in this paper we systematically review and discuss the extensive path undergone by the literature exploring this issue the so called plural forms we address two main questions how to explain the coexistence and often the prevalence of plural forms in many types of businesses are plural forms stable or a transitory phenomenon we describe the most prominent motivations identified in the economics and management literature that drive firms to adopt plural forms and show that their vast majority are related to the mitigation of various types of agency transaction costs we also demonstrate that most of the available pieces of empirical evidence suggest the stability of plural forms over time we conclude by demonstrating the path that has been trailed by the most recent developments

vertical integration and firm boundaries the evidence since ronald h coase s 1937 seminal paper a rich set of theories has been developed that deal with firm boundaries in vertical or input output structures in the last twenty five years empirical evidence that can shed light on those theories also has been accumulating we review the findings of empirical studies that have addressed two main interrelated questions first what types of transactions are best brought within the firm and second what are the consequences of vertical integration decisions for economic outcomes such as prices quantities investment and profits throughout we highlight areas of potential cross fertilization and promising areas for future work

the benefit cost ratio as a decision criteria when managing catastrophes previous work has shown that when projects are non marginal it creates an interdependence among projects this implies that policies to manage catastrophes should not be evaluated in isolation but in conjunction with each other as long as relative risk aversion is sufficiently high the benefits of averting one catastrophe depend positively on the background risk created by other catastrophes this specific bias makes it possible to create upper and lower boundaries on the willingness to pay to manage catastrophes and the optimal policy these boundaries can be used to make inferences on which catastrophes should be averted and not and in which order the upper and lower boundaries depend only on the individual catastrophe s benefit cost ratio and the coefficient of risk aversion which both are easy to identify using standard economic frameworks

a simple state contingent pricing rule for complex intertemporal externalities abstract some externalities such as global warming involve complex relationships between emissions and an environmental state variable with effects over lags of uncertain length coming up with theoretically motivated and practical policy options in such cases has proven difficult deterministic intertemporal general equilibrium models yield what appear to be feasible optimal price paths but only by assuming away many key uncertainties nor do they specify how the possibility of new information should affect the policy path bayesian models allow limited uncertainty and optimal learning based on observed effects of policy changes but suggest a discouraging delay before optimal policy can be identified a full insurance model suggests that risk aversion and fat tailed probabilities of catastrophe imply an implausibly or at least impractically large risk premium implying that practical policy decisions depend so critically on uncertain parameters as to be unavoidably arbitrary this paper proposes an entirely new approach based on the observation that the situation giving rise to a complex intertemporal externality also yields an observable state variable that contains information relevant to the identification of the optimal policy path i derive a simple transformation by which the state variable can yield a good approximation to the optimal externality price i outline assumptions sufficient to yield the transformation and present numerical examples that illustrate its ability to follow linear and nonlinear first best price paths a specific application to greenhouse gases is proposed

multicriteria analysis for agricultural resource management a critical survey and future perspectives abstract this paper reviews multicriteria analysis applied to agricultural resource management the applications utilize either methods for selecting multiattribute discrete alternatives including multiattribute utility theory or methods for solving multiobjective planning problems including goal programming our main purpose is to classify and evaluate the criteria attributes objectives used for modeling agricultural systems and to identify the difficulties for practitioners in applying the methodology the fields of study in agricultural decisions requiring further investigation are also discussed

computing the risky steady state of dsge models this note describes a simple procedure for solving the risky steady state in medium scale macroeconomic models this is the point where agents choose to stay at a given date if they expect future risk and if the realization of shocks is 0 at this date coeurdacier n rey h winant p 2011 the risky steady state the american economic review 101 3 398 401 this new procedure is a direct method which makes use of a second order approximation of the macroeconomic model around its deterministic steady state thus avoiding the need to employ an iterative algorithm to solve a fixed point problem

asset prices and consumption in a model of perpetual youth i construct a general equilibrium overlapping generations model with heterogeneous agents and obtain analytical solutions to asset prices consumption and asset demands individuals have constant absolute risk aversion and a constant probability of dying agents have three stages in their lives in the first stage agents are young and constrained from investing in stocks in the second stage they work and in the third they retire i analyze asset prices numerically and with comparative statics changing any exogenous parameter has large effects on asset prices when there are large demographic changes to the population constrained from investing in stocks

smooth dynamics and computation in models of economic growth abstract in this paper we give an overview of the differentiability properties of the value and policy functions of dynamic programming based upon the differentiability analysis we also derive approximation estimates for the value and policy functions of a discretized model amenable to the computation of optimal solutions

multivariate estimates of the permanent components of gnp and stock prices the economic assumption that a present value relation holds between consumption and income and between stock prices and dividends or the statistical assumption that the consumption income ratio and the dividend price ratio are stationary imply that the permanent or random walk component in each series of a pair must be the same as the permanent component in the other series of a pair either assumption then allows us to estimate the variance of the permanent component of one series gnp stock prices from the variance of the permanent component of the other consumption dividends or from the covariance of the two series permanent components this paper presents such estimates and finds that the permanent components are about half those estimated by similar univariate methods a series of recent papers has examined the importance of a potential unit root to the behavior of real gnp campbell and mankiw 1986 1987 cochrane 1986 clark 1987 and stock prices fama and french 1986 lo and mai if by 0 the series is stationary the response can be any real number which is the innovation in these estimates instead of forcing us to ask the dichotomous question is there a unit root or not they allow us to continuously measure the importance of a potential unit root the actual estimating technique used in these papers varied somewhat cochrane poterba and summers and lo and mai if a series is stationary the variance of k differences will tend to a precursor to this paper appeared under the title spectral density estimates of unit roots we thank masanao aoki lam hansen masao ogaki and chris sims for helpful suggestions the computer programs and data used in this paper are available on request from the authors

bond and stock returns in a simple exchange model this paper studies asset pricing in a general equilibrium representative agent exchange model the assumptions of isoelastic period utility and lognormal endowment allow the derivation of closed form solutions for asset returns without restricting the serial correlation of the log endowment risk premiums on stocks and real bonds are found to be simple functions of relative risk aversion the variance of the log endowment innovation and the weights in the moving average representation of the log endowment the paper analyzes the sign of term premiums the size of the equity premium and the effect of taste shocks on asset prices

information assets technology and organization although there is good reason to expect that the growth of information work and information technology will significantly affect the trade offs inherent in different structures for organizing work the theoretical basis for these changes remains poorly understood this paper seeks to address this gap by analyzing the incentive effects of different ownership arrangement in the spirit of the grossman hart moore ghm incomplete contracts theory of the firm a key departure from earlier approaches is the inclusion of a role for an information asset analogous to the ghm treatment of property this approach highlights the organizational significance of information ownership and information technology for instance using this framework one can determine when 1 informed workers are more likely to be owners than employees of firms 2 increased flexibility of assets will facilitate decentralization and 3 the need for centralized coordination will lead to centralized ownership the framework developed shed

on the size distribution of macroeconomic disasters confidence interval of 2 to 4 the results are robust to uncertainty about the values of the disaster probability and the equity premium and can accommodate seemingly paradoxical situations in which the equity premium may appear to be infinite

contracts entrepreneurs market creation and judgement the contemporary mainstream theory of the firm in perspective this survey gives an overview of the theory of the firm as it is formulated within the contemporary mainstream of economics two groupings of theories are briefly discussed principal agent and incomplete contract models next three of the most recent contributions regarding firms are considered the reference point approach is looked at first followed by a discussion of spulber s book the theory of the firm last we consider the entrepreneurial judgement perspective

modeling synergies in multi criteria supplier selection and order allocation an application to commodity trading abstract we propose a novel meta approach to support collaborative multi objective supplier selection and order allocation ssoa decisions by integrating multi criteria decision analysis and linear programming lp the proposed model accounts for suppliers performance synergy effects within a hierarchical decision structure it incorporates both heterogeneous objective data and subjective judgments of the decision makers dms representing various groups with different voting powers vps we maximize the total value of purchasing tvp by optimizing order quantity assignment to suppliers and taking into consideration their synergies encountered in different time horizons we apply the proposed model to a contractor selection and order quantity assignment problem in an agricultural commodity trading act company we maximize the strategic effectiveness of both the customers and the suppliers minimize risks increase the degree of cooperation between trading partners on all levels of supply chain integration enhance transparent knowledge sharing and aggregation and support collaborative decision making

supplier selection order allocation a two stage multiple criteria dynamic programming approach this paper proposes a two stage multiple criteria dynamic programming approach for two of the most critical tasks in supply chain management namely supplier selection and order allocation in the first stage to address multiple decision criteria in supplier ranking the analytic hierarchy process ahp is employed in the second stage supplier ranks are fed into an order allocation model that aims at maximizing a utility function for the firm as well as minimizing the total supply chain costs subject to constraints on demand capacity and inventory levels a dynamic programming approach is crafted to solve the proposed bi objective model

multi objective models for lot sizing with supplier selection abstract in this paper two multi objective mixed integer non linear models are developed for multi period lot sizing problems involving multiple products and multiple suppliers each model is constructed on the basis of three objective functions cost quality and service level and a set of constraints the total costs consist of purchasing ordering holding and backordering and transportation costs ordering cost is seen as an ordering frequency dependent function whereas total quality and service level are seen as time dependent functions the first model represents this problem in situations where shortage is not allowed while in the second model all the demand during the stock out period is backordered considering the complexity of these models on the one hand and the ability of genetic algorithms to obtain a set of pareto optimal solutions we apply a genetic algorithm in an innovative approach to solve the models comparison results indicate that in a backordering situation buyers are better able to optimize their objectives compared to situations where there is no shortage if we take ordering frequency into account the total costs are reduced significantly

structuring resource allocation decisions a framework for building multi criteria portfolio models with area grouped options multi criteria portfolio modelling has been extensively employed as an effective means to allocate scarce resources for investment in projects when considering costs benefits and risks some of these modelling approaches allow the grouping of projects into organisational areas thus also supporting the decision of resource allocation among organisational units in a way that is collectively efficient for the organisation however structuring in practice a portfolio model using this latter type of approach is not a trivial task how should areas be defined where should new projects be included how should one define the criteria to evaluate performance as far as we know there is very little indication in the operational research and decision sciences literatures on how to structure this type of model this paper suggests different ways to structuring portfolio models where projects are divided into areas and evaluated by multiple criteria and illustrates their use in two action research projects drawing on these experiences it then suggests a general framework for the structuring of such models in practice directions for future research are also identified

preference programming for robust portfolio modeling and project selection in decision analysis difficulties of obtaining complete information about model parameters make it advisable to seek robust solutions that perform reasonably well across the full range of feasible parameter values in this paper we develop the robust portfolio modeling rpm methodology which extends preference programming methods into portfolio problems where a subset of project proposals are funded in view of multiple evaluation criteria we also develop an algorithm for computing all non dominated portfolios subject to incomplete information about criterion weights and project specific performance levels based on these portfolios we propose a project level index to convey i which projects are robust choices in the sense that they would be recommended even if further information were to be obtained and ii how continued activities in preference elicitation should be focused the rpm methodology is illustrated with an application using real data on road pavement projects

learning and climate feedbacks optimal climate insurance and fat tails we study the effect of potentially severe climate change on optimal climate change policy accounting for learning and uncertainty in the climate system in particular we test how fat upper tailed uncertainty over the temperature change from a doubling of greenhouse gases the climate sensitivity affects economic growth and emissions policy in addition we examine whether and how fast uncertainties could be diminished through bayesian learning our results indicate that while overall learning is slow the mass of the fat tail diminishes quickly since observations near the mean provide evidence against fat tails we denote as partial learning the case where the planner rejects high values of the climate sensitivity with high confidence even though significant uncertainty remains fat tailed uncertainty without learning reduces current emissions by 38 relative to certainty indicating significant climate insurance or paying to limit emissions today to reduce the risk of very high temperature changes is optimal however learning reduces climate insurance by about 50 the optimal abatement policy is strongly influenced by the current state of knowledge even though greenhouse gas ghg emissions are difficult to reverse non fat tailed uncertainty is largely irrelevant for optimal emissions policy

internal rationality imperfect market knowledge and asset prices we present a decision theoretic framework in which agents are learning about market behavior and that provides microfoundations for models of adaptive learning agents are internally rational i e maximize discounted expected utility under uncertainty given dynamically consistent subjective beliefs about the future but agents may not be externally rational i e may not know the true stochastic process for payoff relevant variables beyond their control this includes future market outcomes and fundamentals we apply this approach to a simple asset pricing model and show that the equilibrium stock price is then determined by investors expectations of the price and dividend in the next period rather than by expectations of the discounted sum of dividends as a result learning about price behavior affects market outcomes while learning about the discounted sum of dividends is irrelevant for equilibrium prices stock prices equal the discounted sum of dividends only after making very strong assumptions about agents market knowledge

solving asset pricing models with stochastic volatility abstract this paper provides a closed form solution for the price dividend ratio in a standard asset pricing model with stochastic volatility the growth rate of the endowment is a first order gaussian autoregression while the stochastic volatility innovations can be drawn from any distribution for which the moment generating function exists the solution is useful in allowing comparisons among numerical methods used to approximate the nontrivial closed form the closed form solution reveals that when using perturbation methods around the deterministic steady state the approximate solution needs to be sixth order accurate in order for the parameter capturing the conditional standard deviation of the stochastic volatility process to be present

consumption asset pricing with stable shocks exploring a solution and its implications for mean equity returns abstract we study the consumption based asset pricing model due to lucas econometrica 46 1978 1429 the exogenous endowment sequence is modeled as a linear stochastic process driven by stable shocks in an otherwise standard framework the gaussian process emerges as a special case we derive exact analytical solutions for asset prices and returns and provide conditions under which these exist we also study the ability of the model to generate realistic values of observed mean rates of return

huggett economies with multiple stationary equilibria abstract i obtain a closed form solution to a huggett economy with constant absolute risk aversion cara utility when the vector of individual state variables follows a var 1 process with an arbitrary shock distribution the stationary equilibrium is unique if the income process is ar 1 but not necessarily so otherwise with gaussian shocks i provide general sufficient conditions for the existence of at least three equilibria when the income process is either arma 1 1 ar 2 or has a persistent transitory pt representation with negatively correlated shocks the possibility of multiple equilibria calls for caution in comparative statics exercises and policy analyses using heterogeneous agent models as an illustration i provide an example in which the welfare implication of changing the income risk goes in opposite directions depending on the choice of equilibrium

solving asset pricing models with gaussian shocks this paper provides a closed form solution for the price dividend ratio in a standard asset pricing model when the growth rate of the endowment is a first order gaussian autoregression it determines the conditions under which this solution is bounded the findings are useful in allowing comparisons among numerical methods used to approximate the nontrivial closed form the solution method is extended to accommodate multivariate and higher ordered autoregressive processes

the total cost of logistics in supplier selection under conditions of multiple sourcing multiple criteria and capacity constraint abstract little attention is given in the literature to decisions on the appropriate selection of suppliers and on assigning order quantities to these suppliers in the case of multiple sourcing with multiple criteria and with suppliers capacity constraints only a few mathematical programming models to analyse such decisions have been published to date and these have tended to consider only net price as the cost of purchasing although the costs of transportation ordering and storage may be significantly important to the decision in this paper a mixed integer non linear programming model is presented to solve the multiple sourcing problem which takes into account the total cost of logistics including net price storage transportation and ordering costs buyer limitations on budget quality service etc can also be considered in the model an algorithm is proposed to solve the model and the model is illustrated using a numerical example

common mistakes in making value trade offs value trade offs define how much must be gained in the achievement of one objective to compensate for a lesser achievement on a different objective value trade offs that adequately express a decision maker s values are essential both for good decision making in multiple objective contexts and for insightful analyses of multiple objective decisions this paper identifies and illustrates 12 important mistakes frequently made that limit one s ability to determine useful value trade offs it then suggests how to avoid making these mistakes the intent is to provide practical advice for making good value trade offs and hence better decisions

fifth order perturbation solution to dsge models abstract this paper derives a fifth order perturbation solution to dsge models the paper develops a new notation that reduces the notational complexity of high order solutions and yields a faster code the new notation consists of new matrix forms of high order multivariate chain rules and a new representation of the model as a function of one vector variable the algorithm that implements the new notation is between 3 and 55 times faster than dynare depending on model size and solution order

world income components measuring and exploiting risk sharing opportunities a method is constructedfor decomposing the variance of changes in incomes in the world into components to indicate the most important risk sharing opportunities among people of the world a constant absolute risk premium carp model an intertemporal general equilibrium model of the world is presented to permit optimal contract design for a contract designer maximizing a social welfare function the optimal contracts maximize the equilibrium world real interest rate securities are defined in terms of eigenvectors of a transformed variance matrix the method is applied using penn world table data on the g 7 countries 1950

the history of the theory of the firm from marshall to robinson and chamberlin the source of positivism in economics a widely believed story in the folklore of the economics profession is that the theories of perfect competition and monopoly were well established from the time of marshall or perhaps pigou s economics of welfare and that the role of imperfect or monopolistic competition theory was to fill in the middle ground between these extremes it will be shown in this paper that the folklore conflicts with the historical evidence robinson and chamberlin created the theory of perfect competition in the course of inventing imperfect and monopolistic competition theory robinson and chamberlin between them were concerned with the same issues that concerned marshall the difference is that robinson and chamberlin derived their analyses from a few clear axioms while marshall sought to develop his analysis from a well informed but necessarily impressionistic description of actual business behaviour and dynamic processes along with the introduction of indifference analysis to english speaking economists by hicks and allen robinson and chamberlin gave the theory of value and distribution a complete and logically consistent axiomatic basis because their axioms relating to business motivation and behaviour were amenable to empirical verification the work of robinson and chamberlin rendered the theory of value and distribution open to a new empirical criticism it will be argued that the widespread acceptance of friedman s 195 3 positive methodological position was a necessary response to these empirical criticisms if the new axiomatic foundations of the theory of value and distribution were to be as secure as those previously provided by marshall

exact solution of asset pricing models with arbitrary shock distributions abstract the paper provides an exact solution to standard asset pricing models for any distribution of shocks to endowment s growth rate it determines the conditions that guarantee the existence of a stationary bounded equilibrium and examines these conditions for an edgeworth expansion distribution of the shocks the results are extended to the case of multivariate asset pricing models

the firm as a communication network this paper analyzes how organizations can minimize costs of processing and communicating information communication is costly because it takes time for an agent to absorb new information sent by others agents can reduce this time by specializing in the processing of particular types of information when these returns to specialization outweigh costs of communication it is efficient for several agents to collaborate within a firm it is shown that efficient networks involve centralization that individuals delegate tasks to subordinates only if they are overloaded and that the number of transits to the top tends to be equalized across individual information items

four formal izable theories of the firm in this essay i define and compare elemental versions of four theories of the firm these elemental theories are distilled from important contributions by hart holmstrom klein williamson and others although these contributions have been widely cited and much discussed i have found it difficult to understand the commonalities distinctions and potential combinations of these seemingly familiar contributions in this essay therefore i attempt to clarify these issues in three steps i begin with informal summaries of the theories then turn to simple but formal statements of each elemental theory and finally nest the four elemental theories in an integrative framework

a model of competitive stock trading volume a model of competitive stock trading is developed in which investors are heterogeneous in their information and private investment opportunities and rationally trade for both informational and noninformational motives i examine the link between the nature of heterogeneity among investors and the behavior of trading volume and its relation to price dynamics it is found that volume is positively correlated with absolute changes in prices and dividends i show that informational trading and noninformational trading lead to different dynamic relations between trading volume and stock returns

on the stability of the constant relative risk aversion crra utility under high degrees of uncertainty growth models under uncertainty and constant relative risk aversion crra utility are fragile in explaining consumers choice as equilibrium consumption is dependent on distributional assumptions we show that under semi nonparametric distributions general equilibrium models are stable as the existence of expected utility is guaranteed

the contractual nature of the firm for their helpful comments i am grateful to armen a alchian yoram barzel keith leffler john s mcgee and dean worcester 1 ronald h coase the nature of the firm 4 economica 386 1937 the paper however was written several years earlier see note 3 infra 2 the social sciences citation index provides the following information breaking down the period of 1966 80 into three five year periods the total citations of coase s firm paper for each subperiod are 1966 70 17 citations 1971 75 47 citations and 1976 80 105 citations

a note on some limitations of crra utility abstract in a standard environment for choice under uncertainty with constant relative risk aversion crra the existence of expected utility is fragile with respect to changes in the distributions of random variables changes in prior information or the assumption of rational expectations

is the market price of risk infinite abstract in a bayesian model a rational expectations euler equation involves a learning wedge that disconnects the consumer s imrs from the rational expectations pricing kernel the wedge is extremely volatile and explains the high volatility of the rational expectations pricing kernel

on modeling and interpreting the economics of catastrophic climate change with climate change as prototype example this paper analyzes the implications of structural uncertainty for the economics of low probability high impact catastrophes even when updated by bayesian learning uncertain structural parameters induce a critical tail fattening of posterior predictive distributions such fattened tails have strong im plications for situations like climate change where a catastrophe is theoretically possible because prior knowledge cannot place sufficiently narrow bounds on overall damages this paper shows that the economic consequences of fat tailed structural uncertainty along with unsureness about high temperature damages can readily outweigh the effects of discounting in climate change policy analysis

on the existence of expected utility with crra under stur abstract this note shows that in a standard framework for choice under uncertainty expected utility fails to exist with constant relative risk aversion crra when the endowment follows a stochastic unit root stur process

first order risk aversion and the equity premium puzzle abstract this paper integrates yaari s dual theory of choice under uncertainty into a multiperiod context and examines its implications for the equity premium puzzle an important property of these preferences is that of first order risk aversion which implies in our model that the risk premium for a small gamble is proportional to the standard deviation rather than the variance since the standard deviation of the growth rate in aggregate consumption is considerably larger than its variance the model can generate both a small risk free rate and a moderate equity premium