single crossing random utility models we propose a novel model of stochastic choice the single crossing random utility model scrum this is a random utility model in which the collection of preferences satisfies the single crossing property we offer a characterization of scrums based on two easy to check properties the classic monotonicity property and a novel condition centrality the identified collection of preferences and associated probabilities is unique we show that scrums nest both single peaked and single dipped random utility models and establish a stochastic monotone comparative result for the case of scrums

on the simple economics of advertising marketing and product design we propose a framework for analyzing transformations of demand such transformations frequently stem from changes in the dispersion of consumers valuations which lead to rotations of the demand curve in many settings profits are a u shaped function of dispersion high dispersion is complemented by niche production and low dispersion is complemented by mass market supply we investigate numerous applications including product design advertising marketing and sales advice and the construction of quality differentiated product lines we also suggest a new taxonomy of advertising distinguishing between hype which shifts demand and real information which rotates demand

optimal investment under ambiguous technology shocks abstract this paper analyzes the behavior of a firm facing an ambiguous technology shock and the effects of the attitude toward ambiguity on optimal capital investment using the smooth ambiguity model of klibanoff et al 2005 although it seems intuitive that an increase in ambiguity aversion always reduces the optimal capital investment this is not necessarily true because the shape of the production function plays a key role in determining the effect under some conditions we show that the optimal amount of capital investment increases decreases in ambiguity aversion if the production function is substitute complement and that this result is counterintuitive when the production function is substitute furthermore our main results hold if we assume the maxmin preferences in ghirardato et al 2004

optimal risk sharing with background risk this paper examines qualitative properties of efficient insurance contracts in the presence of background risk in order to get results for all strictly risk averse expected utility maximizers the concept of stochastic increasingness is used different assumptions on the stochastic dependence between the insurable and uninsurable risk lead to different qualitative properties of the efficient contracts the new results obtained under hypotheses of dependent risks are compared to classical results in the absence of background risk or to the case of independent risks the theory is further generalized to nonexpected utility maximizers

the economics of career concerns part i comparing information structures many incentives in organizations arise not through explicit formal incentive contracts but rather implicitly through career concerns this paper models career concerns through agents trying to manipulate the market assessment of their future productivity the information flow from current actions to market assessment is therefore crucial in determining the nature of these incentives improved information may either increase or reduce incentives the impact of information provides a major distinction between the explicit and implicit incentives model the paper derives general results on comparisons of information structures which serve as counterparts to the standard results on information structures in the principal agent model sufficient statistic impact of a blackwell garbling comparison of inclusive information structures 1999 the review of economic studies limited

on existence and uniqueness of equilibrium in a class of noisy rational expectations models i study a general class of noisy rational expectations models that nests the standard grossman and stiglitz 1980 and hellwig 1980 models but relaxes the usual assumption of joint normality of asset pay offs and supply and allows for more general signal structures i provide a constructive proof of existence of equilibrium characterize the price function and provide sufficient conditions for uniqueness within the class of equilibria with continuous price functions which are met by both the grossman and stiglitz 1980 models and the hellwig 1980 models with a continuum of investors my solution approach does not rely on the typical conjecture and verify method and i exhibit a number of non normal examples in which asset prices can be characterized explicitly and in a closed form the results presented here open up a broad class of models for applied work to illustrate the usefulness of generalizing the standard model i show that in settings with non normally distributed pay offs shocks to fundamentals may be amplified purely due to learning effects price drifts can arise naturally and the disagreement return relation depends in a novel way on return skewness

the comparative statics on asset prices based on bull and bear market measure abstract for single period complete financial asset markets with representative investors we introduce a bull market measure for uncertain state occurrence and its associated ordering between representative investors in markets based on their marginal rate of substitution between equilibrium consumption allocations among possible states these concepts combine and generalize the likelihood ratio dominance relation between probability prospects of state occurrence and the arrow pratt ordering of risk aversion in expected utility settings by analyzing the comparative statics for bull market effects on equilibrium asset prices we derive some monotone properties of the risk free rate and discounted prices of dividend monotone assets

ordering ambiguous acts we investigate what it means for one act to be more ambiguous than another the question is evidently analogous to asking what makes one prospect riskier than another but beliefs are neither objective nor representable by a unique probability our starting point is an abstract class of preferences constructed to be strictly partially ordered by a more ambiguity averse relation we define two notions of more ambiguous with respect to such a class a more ambiguous i act makes an ambiguity averse decision maker dm worse off but does not affect the welfare of an ambiguity neutral dm a more ambiguous ii act adversely affects a more ambiguity averse dm more as measured by the compensation they require to switch acts unlike more ambiguous i more ambiguous ii does not require indifference of ambiguity neutral elements to the acts being compared second we implement the abstract definitions to characterize more ambiguous i and ii for two explicit preference families maxmin expected utility and smooth ambiguity our characterizations show that the outcome of a more ambiguous act is less robust to a perturbation in probability distribution governing the states third the characterizations also establish important connections between more ambiguous and more informative as defined on statistical experiments by blackwell 1953 and others fourthly we give applications to defining ambiguity in the small and to the comparative statics of more ambiguous in a standard portfolio problem and a consumption saving problem

preservation of more risk averse under expectations abstract the preservation of risk aversion properties of utility functions under expectation operations is of interest in the study of derived utility functions in sequential decision problems and in problems with multiple contemporaneous sources of uncertainty the purpose of this note is to present sufficient conditions for the pratt relation more risk averse to be preserved under expectations

competition in public service provision the role of not for profit providers abstract with public services such as health and education it is not straightforward for consumers to assess the quality of provision many such services are provided by monopoly not for profit providers and there is concern that for profit providers may increase profit at the expense of quality this paper explores the implications of entry by for profit providers when there is unobserved quality the model generates three key policy relevant insights first by developing a novel approach to competition between different organizational forms it frames the relevant trade offs precisely second it shows the value of keeping an incumbent not for profit as an active provider third it characterizes the optimal payment or voucher value to an entrant for each consumer who switches in a way that can be applied empirically

risk aversion and the choice between risky prospects the preservation of comparative statics results most results in what can be termed the comparative statics of risk aversion are obtained when there is only one source of uncertainty the primary example which originally motivated the definition of risk aversion is that more risk averse people are willing to pay a higher premium for insuring against risk it is known that the results do not generally carry over when there is another source of uncertainty the paper develops conditions under which comparative statics results are robust against the introduction of additional sources of uncertainty

changes in background risk and risk taking behaviour economic decision making under uncertainty often takes place in the presence of multiple risks and in markets that are less than complete as a consequence choices about endogenous risks sometimes must be made while simultaneously facing one or more immutable exogenous background risks that are not under the control of the agent and that are independent of endogenous risks it is somehow natural to assume that an exogenous deterioration in background wealth will cause an individual to take more care elsewhere if we define a deterioration for example as making the individual poorer by removing a fixed amount of initial wealth we know from pratt 1964 that decreasing absolute risk aversion dara of an individual s von neumann morgenstern utility function yields this natural result if on the other hand background wealth becomes riskier due to the addition of a zero mean risk that is also statistically independent of all other risks behavior will be more risk averse if and only if preferences are risk vulnerable as defined by gollier and pratt 1996 risk vulnerability described below in section 4 is a stronger notion than dara and includes proper risk aversion pratt and zeckhauser 1987 and standard risk aversion eeckhoudt and kimball 1992 kimball 1993 as particular cases but a deterioration in background wealth may encompass more complicated distribution changes than the introduction of another statistically independent risk in this paper we examine background wealth deteriorations that take the form of both general firstand second degree stochastic dominance changes in risk fsd and ssd respectively in particular we determine conditions that are both necessary and sufficient for each of these two types of background risk changes to imply more risk averse behavior on the part of the individual for the case of fsd changes this condition turns out to be ross stronger characterization of decreasing absolute risk aversion in the case of general ssd changes in the distribution of background wealth the condition derived is a stronger version in ross sense of the conditions characterizing preferences that are locally risk vulnerable in the sense of gollier and pratt the necessary and sufficient conditions derived are fairly restrictive upon preferences however if we take as positive behavior that individuals act in a more risk averse manner whenever the distribution of background wealth deteriorates these conditions place canonical limits upon appropriate utility representations at the very least they

does risk sharing increase with risk aversion and risk when commitment is limited i consider a risk sharing game with limited commitment and study how the discount factor above which perfect risk sharing is self enforcing in the long run depends on agents risk aversion and the riskiness of their endowment when agents face no aggregate risk a mean preserving spread may destroy the sustainability of perfect risk sharing if each agent s endowment may take more than three values with aggregate risk the same can happen with only two possible endowment realizations with respect to risk aversion the intuitive comparative statics result holds without aggregate risk but it holds only under strong assumptions in the presence of aggregate risk in simple settings with two endowment values i also show that the threshold discount factor co moves with popular measures of risk sharing

some stronger measures of risk aversion in the small and the large with applications the arrow pratt measures of risk aversion for von neumann morgenstern utility functions have become workhorses for analyzing problems in the microeconomics of uncertainty they have been used to characterize the qualitative properties of demand in insurance and asset markets to examine the properties of risk taking in taxation models and to study the interaction between risk and life cycle savings problems to name just a few applications equally importantly they have generated the linear risk tolerance class of utility functions which has provided canonical examples in such diverse areas as portfolio theory and the theory of teams despite these successes there have been a number of areas for which the results have been weaker than hoped it is natural to use the risk aversion measures to compare the behavior of individuals in risky choice situations for example consider the individual portfolio choice problem in a two asset world with a riskless asset and a risky asset if individual a has a uniformly higher arrow pratt coefficient of risk aversion than individual b then b will always choose a portfolio combination with more wealth invested in the risky asset but suppose that both assets are risky now there is no obvious sense in which the more risk averse individual can be said to hold a less risky portfolio but it seems strange that such a simple alteration should destroy the analytics which support the basic intuition similarly consider the basic insurance problem if one individual a is more risk averse than another b in the arrow pratt sense it follows that a will pay a larger premium to insure against a random loss than will b typically though an individual evaluates partial rather than total insurance that is only some gambles can be insured against and others must be retained in this case even when the gambles which are retained are independent from those which are insured it is no longer true that the individual whose arrow pratt measure of risk aversion is higher will pay a larger insurance premium the situation is no better when we consider comparative statics exercises for a single individual decreasing absolute risk aversion in the sense of arrow and

monotone comparative statics under uncertainty this paper analyzes monotone comparative statics predictions in several classes of stochastic optimization problems the main results characterize necessary and sufficient conditions for comparative statics predictions to hold based on properties of primitive functions that is utility functions and probability distributions the results apply when the primitives satisfy one of the following two properties i a single crossing property which arises in applications such as portfolio investment problems and auctions or ii log supermodularity which arises in the analysis of demand functions affiliated random variables stochastic orders and orders over risk aversion

marginal conditional stochastic dominance this paper introduces the concept of marginal conditional stochastic dominance mcsd which states the conditions under which all risk averse individuals when presented with a given portfolio prefer to increase the share of one risky asset over that of another mcsd rules also answer the question of whether all risk averse individuals include a new asset in their portfolio when assets returns are correlated mcsd criteria are expressed in terms of the probability distributions of the assets and of the underlying portfolio an empirical application of mcsd is provided using stocks traded on the new york stock exchange mcsd rules are used to show that in the long run one cannot assert that the market portfolio is inefficient

choosing between risky prospects the characterization of comparative statics results and location independent risk we consider expected utility maximizers choosing from a family of risky prospects and examine how choice is influenced by the decision makers attitude to risk if the family of risky prospects can be ordered so that as decision makers are more risk tolerant they choose a gamble higher in the ordering then it is natural to say that the family of risky prospects admit a comparative static result the paper characterizes when comparative static results of this sort exist an application is to propose a criterion of location independent riskiness

precautionary bidding in auctions we analyze bidding behavior in auctions when risk averse buyers bid for a good whose value is risky we show that when the risk in the valuations increases dara bidders will reduce their bids by more than the appropriate increase in the risk premium ceteris paribus buyers will be better off bidding for a more risky object in first price second price and english auctions with affiliated common interdependent values this precautionary bidding effect arises because the expected marginal utility of income increases with risk so buyers are reluctant to bid so highly we also show that precautionary bidding behavior can make dara bidders prefer bidding in a common values setting to bidding in a private values one when risk neutral or cara bidders would be indifferent thus the potential for a winner s curse can be a blessing for rational dara bidders

money housing and world market the dialectic of globalised production this article offers an interpretation of the domestic and global dimensions of the us housing financial and economic crisis in a marxian framework my key argument is that the origins of the great recession can be fully understood only within an analysis of the system of globalised production and the corresponding division of labour manifest in the symbiotic relationship between the financialised us centred core and the commodity producing periphery the imbalance between production and finance in the us economy mirrors the global imbalance between the ability to produce and the capacity to consume