an efficiency theorem for incompletely known preferences there are n agents who have von neumann morgenstern utility functions on a finite set of alternatives a each agent i s utility function is known to lie in the nonempty convex relatively open set ui suppose l is a lottery on a that is undominated meaning that there is no other lottery that is guaranteed to pareto dominate l no matter what the true utility functions are then there exist utility functions ui ui for which l is pareto efficient this result includes the ordinal efficiency welfare theorem as a special case

reputation and hierarchy in dynamic models of employment the employment relationship with employees ability and their actions both private information thus combining adverse selection with moral hazard is modeled as a repeated game with self enforcing contracts being perfect bayesian nash equilibria under termination contracts the equilibrium contract structure consists of a hierarchy of ranks finite in number even though ability is continuous reputation acts as an effective device for worker discipline without the need for involuntary unemployment selection by bonding is not in general incentive compatible but selection by promotion of employees through the ranks is many other features correspond to observed employment structures

uncertainty and risk in financial markets this paper considers a general equilibrium model in which the distinction between uncertainty and risk is formalized by assuming agents have incomplete preferences over statecontingent consumption bundles as in bewley 1986 without completeness individual decision making depends on a set of probability distributions over the state space a bundle is preferred to another if and only if it has larger expected utility for all probabilities in this set when preferences are complete this set is a singleton and the model reduces to standard expected utility in this setting we characterize pareto optima and equilibria and show that the presence of uncertainty generates robust indeterminacies in equilibrium prices and allocations for any specification of initial endowments we derive comparative statics results linking the degree of uncertainty with changes in equilibria despite the presence of robust indeterminacies we show that equilibrium prices and allocations vary continuously with underlying fundamentals equilibria in a standard risk economy are thus robust to adding small degrees of uncertainty finally we give conditions under which some assets are not traded due to uncertainty aversion

the effect of punishment on firm compliance with hazardous waste regulations abstract this paper examines the effect of epa s dramatic 1991 increase in the penalties associated with violations of hazardous waste regulations on firm compliance although data from epa s rcra information system show an increase in detected violations after the penalty change once inspection levels are incorporated into the analysis through a censored bivariate probit model i find that violations have decreased since the penalty change however the decrease in violations appears small relative to the increase in recommended penalty levels i also find evidence that the likelihoods of inspection and compliance vary significantly across regions

transaction costs and efficiency of portfolio strategies abstract some recent results for frictionless economies show that popular dynamic portfolio strategies such as stop loss and lock in are inefficient i e for each of these strategies there exists an alternative portfolio strategy that gives the same final payoff distribution at lower initial costs however the alternative strategies require considerably more active trading than the simple strategies the results rely heavily on the assumption of no transaction costs under this assumption the initial investment required is a linear function of the prices of the contingent claims that build the final payoff distribution in this paper we demonstrate that even for modest levels of transaction costs the efficient strategies are more costly than the simple strategies i e a strategy that replicates the final payoff distribution of an efficient strategy is excessively costly due to the transaction costs and the heavy trading involved since the initial investment is no longer a linear function of the contingent claims the optimization problems to find the most efficient strategy are complicated combinatorial optimization problems which can only be solved for trees with a small number of steps in a world without transaction costs options are redundant instruments since all payoff distributions can be replicated by trading in stocks and bonds in the second half of this paper we show that the use of options in a world with transaction costs enables investors to realize final value distributions at lower initial costs than would be possible with trades in stocks an bonds only hence although in theory options do not give rise to other portfolio strategies they do in a more restrictive setting with transaction costs

the economics of crime and punishment an analysis of optimal penalty this paper demonstrates the optimality of a non maximal penalty in a hierarchical enforcement structure the penalty is chosen by the social planner to maximize the probability of monitoring and to minimize the probability of transgression we compare the optimal penalty levels with and without ex post flexibility wherein the players are allowed to alter their decision after they observe the social planner s choice 2000 elsevier science s a all rights reserved

pareto optima and equilibria when preferences are incompletely known an exchange economy in which agents have convex incomplete preferences defined by families of concave utility functions is considered sufficient conditions for the set of efficient allocations and equilibria to coincide with the set of efficient allocations and equilibria that result when each agent has a utility in her family are provided welfare theorems in an incomplete preferences framework therefore hold under these conditions and efficient allocations and equilibria are characterized by first order conditions

intertemporal equilibria with knightian uncertainty we study a dynamic and infinite dimensional model with incomplete multiple prior preferences in interior efficient allocations agents share a common risk adjusted prior and subjective interest rate interior efficient allocations and equilibria coincide with those of economies with subjective expected utility and priors from the agents multiple prior sets a specific model with neither risk nor uncertainty at the aggregate level is considered risk is always fully insured for small levels of ambiguity there exists an equilibrium with inertia where agents also insure fully against knightian uncertainty when the level of ambiguity exceeds a critical threshold full insurance no longer prevails and there exist equilibria with inertia where agents do not insure against uncertainty at all we also show that equilibria with inertia are indeterminate

hierarchical design and enforcement of income tax policies abstract a hierarchical model of tax compliance is studied in which the government selects a tax policy and then delegates the responsibility to collect taxes to the irs there is a fixed distribution of income in the economy individuals differ by their income which is known niether to the government nor to the irs we completely characterize the solution to the irs s revenue maximizing problem when taxpayers are risk neutral the optimal auditing policy divides the reported incomes into at most three groups we show that the government provides a smaller budget to the irs than the irs would wish

the impact of liberalization on bureaucratic corruption abstract liberalization increases the number of goods available for consumption within a country since bureaucrats value variety this raises the marginal utility of accepting a bribe this benefit effect is counteracted by an increasing cost effect from corruption deterrence activities that arise due to greater international pressure to curb corruption the interaction of these two effects can lead to a non monotonic relation between liberalization and corruption moreover pre commitment to deterrence activities is shown to be more effective in controlling corruption empirical evidence supports the existence of a non monotonic relation between economic openness and corruption among developing countries

inefficient dynamic portfolio strategies or how to throw away a million dollars in the stock market a number of portfolio strategies followed by practitioners are dominated because they are incompletely diversified over time the payoff distribution pricing model is used to compute the cost of following undiversified strategies simple numerical examples illustrate the technique and computer generated examples provide realistic estimates of the cost of some typical policies using reasonable parameter values the cost can be substantial and should not be ignored by practitioners a section on generalizations shows how to extend the analysis to term structure models and other general models of returns this abstract was borrowed from another version of this item

regulatory errors optimal fines and the level of compliance abstract this paper shows that with a hierarchical structure of enforcement regulatory errors cause the optimal penalty to be non maximal even if offenders are risk neutral and fines are pure transfers and the private benefit from violation is strictly less than the social cost for all individuals in contrast with error free monitoring no finite fine is optimal within the same hierarchical structure also full compliance is an equilibrium outcome in the presence of errors whereas in the absence of errors the regulator can achieve only partial compliance

optimal strategies under omega ratio abstract we study portfolio selection under the objective of maximizing the omega ratio proposed by keating and shadwick 2002 as an alternative to the sharpe ratio for performance assessment of investment strategies we show that in a continuous time setting of the financial market the problem is ill posed i e maximizing the omega ratio leads to excessive risk taking by imposing additional restrictions we show that the omega ratio maximizing strategy is still very risky and may coincide with the choice made by risk neutral investors we conclude that caution is needed when using the omega ratio for making asset allocation decisions

an explanation of international differences in education and workplace training abstract we develop a simple search equilibrium model of workplace training and education based on two features first investment in education improves job related learning skills and reduces training costs by firms second firms with vacant skilled job slots can choose between recruitment from the market and training compared to germany and japan the us has both a higher inflow rate into unemployment and a higher efficiency of the matching process while the combined effect of these differences on the share of educated labor is ambiguous the effect on the percentage of firms undertaking workplace training is to unambiguously reduce it

optimal management of transfers an odd paradox abstract this paper considers the case of transfers when there exists a serious preference misalignment between the transfer maker and the beneficiary the former wants to reduce the resulting outcome discrepancy through monitoring the use of the transfer and imposing sanctions if the discrepancy proves too large this external discipline combines with the internal discipline of the beneficiary that is his her willingness and ability to align with the transfer maker s objective besides the fact that costs of monitoring and sanctioning are explicitly taken into account an original feature of our model specification is that the two types of discipline are made comparable they can be summed up to obtain an aggregate discipline we show that paradoxically an exogenous improvement of internal discipline may be over compensated by a fall of external discipline total discipline thus decreases and the discrepancy between the actual and the intended uses of the transfer increases instead of decreasing another consequence is that the relationship between internal and total disciplines may be non monotonic these results generalize to alternative specifications of the basic model

corruption in tax administration abstract we extend the game theoretic model of graetz reinganum and wilde 1986 to allow for corruption in tax administration in the presence of corruption audit rates are generally higher than in its absence in fact in the presence of corruption it is possible to sustain equilibria in which all returns are audited moreover when some auditors accept bribes it is possible for increases in the fine rate or the tax rate to reduce expected government revenue

an empirical test of pricing kernel monotonicity summary a large class of asset pricing models predicts that securities which have high payoffs when market returns are low tend to be more valuable than those with high payoffs when market returns are high more generally we expect the projection of the stochastic discount factor on the market portfolio that is the discounted pricing kernel evaluated at the market portfolio to be a monotonically decreasing function of the market portfolio numerous recent empirical studies appear to contradict this prediction the non monotonicity of empirical pricing kernel estimates has become known as the pricing kernel puzzle in this paper we propose and apply a formal statistical test of pricing kernel monotonicity we apply the test using 17 years of data from the market for european put and call options written on the s p 500 index statistically significant violations of pricing kernel monotonicity occur in a substantial proportion of months suggesting that observed non monotonicities are unlikely to be the product of statistical noise copyright 2014 john wiley sons ltd

distributional analysis of portfolio choice trading in a market is compared with receiving some particular consu mption bundle given increasing state independent preferences and complete markets the analysis focuses on the distribution price of t he particular bundle the distributional price is the price of the ch eapest utility equivalent bundle sold in the market the distribution al price is determined by the distribution functions of the outside b undle and the state price density simple portfolio performance measu res illustrate the value of the approach unlike capm based measures these measures are valid even when superior information is the sourc e of superior performance copyright 1988 by the university of chicago

avoidance screening and optimum enforcement a standard assumption in the economic literature on crime and punishment is that fines are costless transfers given this assumption several economists have argued that it is optimal to set the fine for engaging in a proscribed activity as high as possible the argument is a simple one raising the probability of a fine is costly since it requires devoting more resources to monitoring and apprehending individuals in contrast raising the magnitude of a fine is costless therefore the least costly way to achieve a given expected fine is to set the fine as high as possible presumably equal to the offender s wealth and adjust its probability so that the desired expected fine is obtained

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

reasonable doubt and the optimal magnitude of fines should the penalty fit the crime models of the enforcement compliance relationship have assumed that both the probability and magnitude of fines are independent choice variables of policy makers these models indicate that it may be optimal to monitor with lowfrequency but to inflict uniformly maximal penalties for all infractions detected this article shows that if the judicial system is built on the reasonable doubt test then the penalty and the probability of conviction are not independent in particular as the penalty increases the probability of conviction falls as a result uniformly maximal penalties may actually encourage crime rather than deter it this article shows that optimal fines should rise with the severity of the infraction that is the penalty should fit the crime models of the enforcement compliance relationship generally treat both the probability and magnitude of fines as independent choice variables of the government this approach has led becker 1968 and others to conclude that it is optimal to set uniformly maximal penalties for all crimes and to set the probability of conviction at the minimum level necessary to enforce compliance with the law while this normative prescription is natural and intuitive there still remains a larger positive question of why in most nations of the world penalties are not uniformly high but rather rise with the severity of the crime one possible resolution of the positive and normative questions may lie in the fact that penalties and probabilities of conviction are not generally independent convictions are typically determined by judges or jurors who are instructed to convict only if the evidence convinces them beyond a reasonable doubt that the accused is guilty psychologists however have found that a juror s willingness to convict may be influenced by more than just the evidence jurors are very sensitive to the potential penalties that defendants may pay

stochastic dominance and expected utility survey and analysis while stochastic dominance has been employed in various forms as early as 1932 it has only been since 1969 1970 that the notion has been developed and extensively employed in the area of economics finance agriculture statistics marketing and operations research in this survey the first second and third order stochastic dominance rules are discussed with an emphasis on the development in the area since the 1980s

how large are the benefits from using options the paper explores the economic value of being able to span market outcomes through the use of options we model an economy with a single risky asset consumption takes place at one date corresponding to the horizon of all investors options on the consumption good are not redundant securities in the economy because volatility is uncertain the model enables us to examine the benefits to investors of using options to optimize their investments within this model the gains from the use of options appear to be relatively minor

asset demands without the independence axiom an important application of the theory of choice under uncertainty is to asset markets and an important property in these markets is a preference for portfolio diversification if an investor is an expected utility maximizer then s he is risk averse if and only if s he exhibits a preference for diversification this paper examines the relationship between risk aversion and portfolio diversification when preferences over probability distributions of wealth do not have an expected utility representation

on the duality between prior beliefs and trading demands in an abstract model with asymmetric information we show that there is a duality relationship between the prior beliefs and trading demands of bets for any given individual then we aggregate all the agents to obtain a second duality relationship between common prior beliefs and trading possibilities we easily derive from these relationships the no trade theorem and its converse general efficiency results can be obtained moreover our framework is sufficiently general to cover special cases proved previously for example econometrica 62 1994 1327 discussion paper 83 center for rationality and interactive decision theory the hebrew university of jerusalem 1995 j econom theory 91 2000 127 gameseconom behav 24 1998 172 yet our argumentsare both simple and intuitive r 2003 published by elsevier science usa

employment tenure and earnings profiles in japan and the united states comments the relationship between job tenure and annual earnings in japan has received considerable attention from social scientists examining employment contracts and the japanese compensation system in their widely cited article masanori hashimoto and john raisian 1985 using data for 1980 showed that japanese men have greater job tenure than comparable workers in the united states and that the earnings of japanese men rise more rapidly with increased tenure they found that an additional year of tenure increases earnings in both small and large firms in japan more than does an additional year of general market experience their results for the united states indicate that general market experience increases earnings more than an additional year of job tenure the 1970 s and 1980 s were a period of substantial change in japanese labor markets due to the rapid aging of the population and the restructuring of the economy following the oil crisis the present analysis extends the work of hashimoto and raisian by estimating earnings equations for japanese men for the years 1971 1976 1981 and 1986 specifically we wish to investigate whether hashimoto and raisian s findings have been stable over time or whether changes in the labor market have altered the importance of tenure relative to total labor market experience in the japanese labor market i changes in the labor market

equilibrium unemployment with internal labour markets the flow approach to the labour market is based on a clear distinction between trade and production this paper argues that this separation is not realistic because many firms in developed economies usually fill an important share of their vacancies by upgrading incumbent employees the implications of the existence of internal labour markets are explored with the help of a simple model that extends the well known pissarides setup the main result is that the distribution of unemployment by education is correlated with the relative importance of internal labour markets in particular i show that more internalization is associated both with more inequality in the distribution of unemployment with the burden falling mainly on the less educated and with less inequality in the distribution of wages by education the model also generates in a simple way upward sloping wage profiles which are offered by firms with internal labour markets to their recruits who face a nonzero probability of promotion to a skilled job

equilibrium pricing in incomplete markets given the exogenous price process of some assets we constrain the price process of other assets that are characterized by their final payoffs we deal with an incomplete market framework in a discrete time model and assume the existence of the equilibrium in this setup we derive restrictions on the state price deflators these restrictions do not depend on a particular choice of utility function we investigate numerically a stochastic volatility model as an example our approach leads to an interval of admissible prices that is more robust than the arbitrage pricing interval

regulating externalities through testing abstract testing for compliance with regulation of a negative externality is analyzed in a strategic framework the outcome is described where the number tested and the penalties for observed noncompliance are each controlled by different agencies or by different levels within the regulatory agency and where the number tested cannot be precommitted comparative statics results are provided and the equilibrium is compared with the welfare optimum for different objectives of those doing the testing it is shown that the actual enforcement decision can sometimes be optimally delegated even if those doing the enforcement have objectives different from minimizing expected social cost

hedge fund performance 1990 2000 do the money machines really add value we investigate the claim that hedge funds offer investors a superior risk return tradeoff we do so using a continuous time version of dybvig s 1988a 1988b payoff distribution pricing model the evaluation model which does not require any assumptions with regard to the return distribution of the funds to be evaluated is applied to the monthly returns of 77 hedge funds and 13 hedge fund indices from may 1990 april 2000 the results show that as a stand alone investment hedge funds do not offer a superior risk return profile we find 12 indices and 72 individual funds to be inefficient with the average efficiency loss amounting to 2 76 per annum for indices and 6 42 for individual funds part of the inefficiency cost of individual funds can be diversified away funds of funds however are not the preferred vehicle for this as their performance appears to suffer badly from their double fee structure looking at hedge funds in a portfolio context results in a marked improvement in the evaluation outcomes seven of the 12 hedge fund indices and 58 of the 72 individual funds classified as inefficient on a stand alone basis are capable of producing an efficient payoff profile when mixed with the s p 500 the best results are obtained when 10 20 of the portfolio value is invested in hedge funds

on the job search in a matching model with heterogeneous jobs and workers this paper considers a matching model with heterogenous jobs unskilled and skilled and workers low and high educated which allows for on the job search by mismatched workers the latter are high educated workers who transitorily accept unskilled jobs and continue to search for skilled jobs our findings show that on the job search introduces an additional source of between and within group wage inequality furthermore the higher quit rate of mismatched workers exerts a negative externality on unskilled jobs and weakens the labour market position of low educated workers this last feature changes the effects of skill biased technological change and it alters the response of the labour market to shifts in the skill distribution this paper has been written for presentation as an invited lecture at the annual conference of the european association of labour economics eale 2003 seville 18 21 september 2003 we are very grateful to maite blazquez for excellent research assistance we also wish to thank barbara petrongolo participants in seminars at uc3m core essex and lse for helpful comments and especially j albrecht for his insightful discussion on a preliminary draft of this paper the usual disclaimer applies

liquidity and valuation in an uncertain world abstract during the 2007 2009 financial crisis there was little or no trading in a variety of financial assets even though bid and ask prices existed for many of these assets we develop a model in which this illiquidity arises from uncertainty and we argue that this new form of illiquidity makes bid and ask prices unsuitable as metrics for establishing fair value for these assets we show how the extreme uncertainty that traders face can be characterized by incomplete preferences over portfolios and we use bewley s 2002 model of decision making under uncertainty to derive equilibrium quotes and the nonexistence of trading at these quotes we then suggest alternatives for valuing assets in illiquid markets

on the optimality of path dependent structured funds the cost of standardization abstract this paper examines the suitability of an important class of standard financial structured products namely those whose performances are based on smoothing the return of a given risky underlying asset while providing a guarantee at maturity using various assumptions about the customers attitudes towards risk we show that such standardized products are not optimal even if the financial market volatility is constant as a by product we provide in particular the optimal portfolio value in the regret rejoice framework to go further with the notion of aversion of getting a return smaller than the risk free one using the notion of compensating variation we determine for the first time the monetary losses of providing these standardized products instead of the optimal ones to the customers we show that these monetary losses can be very significant when the volatility of the risky asset is stochastic from the operational point of view such results highly suggest to trade on the volatility index vix and or to introduce derivatives written on it when selling standardized funds in order to better meet investors needs and preferences

on environmental taxation under uncertain environmental damage this paper addresses optimal taxation when therelationship between the consumption of a dirty good and the resulting environmentaldamage is uncertain and treated as a randomvariable by policy makers the main purpose isto analyze how increased uncertainty measuredas a mean preserving increase in the spread ofthis random variable affects the optimalcommodity tax on the dirty consumption good incase the only task of government is to correctthe environmental externality and if thepreferences are characterized by nondecreasingabsolute risk aversion we find that thecommodity tax on the dirty consumption goodincreases in response to additionaluncertainty if on the other hand thegovernment provides a public good and uses alump sum tax in addition to the commodity tax it is possible that the commodity tax decreasesas a response to additional uncertainty evenif the preferences are characterized bynondecreasing absolute risk aversion a similarresult emerges although for different reasons if the lump sum tax is replaced by a laborincome tax

efficient trading strategies in the presence of market frictions we provide a price characterization of efficient contingent claims that is chosen by at least a rational agent in multiperiod economies with market frictions frictions include market incompleteness transaction costs short selling and borrowing costs we characterize the inefficiency cost of a trading strategy its required investment minus the largest amount necessary to obtain the same utility level and we propose a measure of portfolio performance we show that arbitrage bounds cannot be tightened based on efficiency without restricting preferences or endowments we observe common investment strategies becoming inefficient with market frictions and others rationalized by them in this article we characterize efficient contingent claims to future consumption consumption bundles in multiperiod economies with uncertainty taking a wide range of market frictions into account 1 such as dynamic market

auditing and competitive bidding in the public sector abstract this paper investigates the impact of a ministry s budget size on the choice between auditing a niskanen bureau and employing competitive bidding in the provision of a publicly funded good the ministry s marginal expected payoff increases fastest with budget size for auctioning as opposed to auditing however the ministry is shown to switch from a purely public provision to a competitive provision as the budget size increases even if expected fixed costs favor the audit the study contributes to the literature by extending the niskanen framework and by endogenizing the institutional arrangements for the provision of public sector goods

subjective beliefs and ex ante trade we study a definition of subjective beliefs applicable to preferences that allow for the perception of ambiguity and provide a characterization of such beliefs in terms of market behavior using this definition we derive necessary and sufficient conditions for the efficiency of ex ante trade and show that these conditions follow from the fundamental welfare theorems when aggregate uncertainty is absent our results show that full insurance is efficient if and only if agents share some common subjective beliefs our results hold for a general class of convex preferences which contains many functional forms used in applications involving ambiguity and ambiguity aversion we show how our results can be articulated in the language of these functional forms confirming results existing in the literature generating new results and providing a useful tool for applications

to comply or not to comply pollution standard setting under costly monitoring and sanctioning in this paper we characterize optimal regulatory policies composed of a pollution standard a probability of inspection and a fine for non compliance in a context where both monitoring and sanctioning are socially costly and the penalty may include gravity and non gravity components at the regulator s discretion under given penalties the optimal policy entails compliance with the standard as long as a quite intuitive condition is met non compliant policies may include standards even below the pollution levels that minimize the sum of abatement costs and external damages interestingly the appropriate structure of the penalty under non compliance is highly progressive while the best possible shape of the fine under compliance is linear if the regulator is entitled to choose the structure of the fine linear penalties are socially preferred and the optimal policy induces compliance

internal labour markets causes and consequences the paper analyzes the causes and consequences of internal labor market rules that yield long tenure promotion from within seniority pensions and due process in dismissals about half the workforce are estimated to be in such markets competitive reasons for internal labor markets as a response to specific training and arms length relationships between workers and firms are surveyed these reasons are found to be consistent with the pattern of internal labor markets among non union firms however some internal labor markets e g among small unionized firms are probably a response to union pressure and government regulations in these circumstances low labor mobility could pose problems for policy copyright 1991 by oxford university press

endogenous public sector budgeting to centralize or not in this paper the impact of budget size on a government s choice to centralize or decentralize the budgetary process is investigated using asymmetric information differing preferences and endogenous budgetary arrangements the central government chooses between a budgetary process that excludes the regional board centralization and one that includes the board decentralization in the determination of program budget levels it is predicted that the central government will decentralize the budgetary process at low and centralize at high overall budget levels switching from decentralization to centralization is predicted to

worker financed versus firm sponsored training how are skilled workers supplied to the economy a search and matching model of general human capital is developed to contrast worker financed training with firm sponsored training to evaluate which type of training might prevail in the economy it will be shown that firm sponsored training is more likely to occur when there is greater friction in the labour market whereas worker financed training prevails in a less frictional market moreover the model has multiple equilibria in labour markets with intermediate friction comparative statistics exercises tell us that reductions in labour market friction result in less firm sponsored training in the economy but encourage worker financed training

youth labour markets in spain education training and crowding out abstract the stylised facts describing the poor performance of the youth labour market in spain over the last two decades entailing high unemployment rates for both higher and lower educated workers over education and low intensity of on the job training are explained through a simple matching model where higher educated workers crowd out lower educated ones from their traditional entry jobs in this model a combination of rigid labour market institutions and an increase in the relative supply of higher educated workers harms the training prospects of lower educated workers

stochastic dominance and expected utility while stochastic dominance has been employed in various forms as early as 1932 it has only been since 1969 1970 that the notion has been developed and extensively employed in the area of economics

financial market structures revealed by pricing rules efficient complete markets are prevalent abstract it is well known that when an arbitrage free financial market is incomplete or has tradable financial assets with frictions there must be multiple risk neutral probability measures the main motivation for the present study is to elucidate what type of market structure usually emerges from pricing rules first we obtain that finitely generated pricing rules characterized by polytopes of probabilities capture the class of all finite arbitrage free financial markets that are potentially incomplete or subject to frictions affecting tradable assets next we provide a novel characterization of efficient securities and introduce related notions of market completeness that underlies pricing rules our main result shows that the class of efficient complete markets with bid ask spreads is the prevalent case revealed by finitely generated pricing rules

a definition of uncertainty aversion a definition of uncertainty or ambiguity aversion is proposed it is argued that the definition is well suited to modelling within the savage as opposed to anscombe and aumann domain of acts the defined property of uncertainty aversion has intuitive empirical content behaves well in specific models of preference multiple priors and choquet expected utility and is tractable tractability is established through use of a novel notion of differentiability for utility functions called eventwise differentiability

delegation as commitment the case of income tax audits in this article we study the value of delegating authority over income tax audit policy arising from the incompleteness of contracts consider a utilitarian government whose ability to commit is limited to aggregate dimensions of its audit policy as publicly verifiable information about detailed allocations of audit budgets is not available we show that the welfare level associated with the full commitment solution can be attained by delegating authority over audit policy to a manager the latter is offered a simple incentive scheme based only on the aggregate variables which are publicly observable in contrast if the government retains authority direct commitment to these same variables does not allow the full commitment welfare level to be achieved thus despite sharing a common informational basis delegation may perform better than centralized arrangements in the presence of incomplete contracts

self selection and pareto efficient taxation abstract this paper analyses the set of pareto efficient tax structures the formulation of the problem as one of self selection not only shows more clearly the similarity between this problem and a number of other problems such as the optimal pricing of a monopolist which have recently been the subject of extensive research but also allows the derivation of a number of new results we establish i under fairly weak conditions randomization of tax structures is desirable ii if different individuals are not perfect substitutes for one another in production then the general equilibrium effects until now largely ignored in the literature of changes in the tax structure may be dominant in determining the optimal tax structure in particular if the relative wage of high ability and low ability individuals depends on the relative supplies of labor the optimal tax structure entails a negative marginal tax rate on the high ability individuals and a positive marginal tax rate on the low ability individuals the marnitude of which depends on the elasticity of substitution iii if individuals differ in their preferences pareto efficient taxation may entail negative marginal tax rates for high incomes while iv if wage income is stochastic the marginal tax rate at the upper end may be 100 our analysis thus makes clear that the main qualitative properties of the optimal tax structure to which earlier studies called attention are not robust to these attempts to make the theory more realistic