rational panics and stock market crashes abstract this paper offers an explanation for stock market crashes which focuses on the role of rational but uninformed traders we show that uninformed traders can precipitate a price crash because as prices decline they surmise that informed traders received negative information which leads them to reduce their demand for assets and drive the price of stocks even lower the model yields several implications such as that crashes can occur even when the fundamentals are strong and that the magnitude of the crash depends on the fraction of uninformed investors and the amount of unsophisticated passive investing present in the market

information aggregation in common value auctions a key question in information economics and finance is whether prices aggregate information in a competitive environment that is when agents are endowed with private information does competition lead in the limit to prices which would occur if all information were public this paper examines the asymptotic properties of prices in common value auctions when the number of bidders becomes large the main idea in this paper is to separate the issue of information aggregation from the issue of revenue efficiency we also distinguish between the amount of information prices contain and the degree to which prices approximate the asset s value using this approach we get a simple characterization of the limiting distribution of prices we are not only able to answer whether prices converge to the asset s value but also get an explicit form for the limiting distribution prices converge to the expected value of the asset conditional on the information possessed by what we call the pivotal bidder this provides insights on how the auction format and the information structure influence the limiting behavior of prices it shows that the limiting distribution of prices can be derived from the statistical properties of certain order statistics this lets us abstract from the specific equilibrium bidding strategies for example we show that while the first and second price auction have different equilibrium strategies they share a similar limiting distribution of prices these auctions yield different limiting distributions from auctions such as the english auction or kn auction our

the possibility of informationally efficient markets abstract a rational expectations equilibrium with positive demand for financial information does exist under fully revealing asset price contrary to a wide held conjecture whereas a continuum of investors is inconsistent with fully revealing equilibrium finitely many investors with average portfolios demand information in equilibrium if they can adjust portfolio size in an additive signal return model more information diminishes the expected excess return of a risky asset so that investors who only have a choice of portfolio composition or whose asset endowments strongly differ from the average portfolio are worse off under fully revealing price information market equilibria both with and without information acquisition are pareto efficient

the pricing effects of ambiguous private information when private information is observed by ambiguity averse investors asset prices may be informationally inefficient in rational expectations equilibrium this inefficiency implies lower asset prices as uninformed investors require a premium to hold assets and higher return volatility relative to informationally efficient benchmarks moreover asset returns are negatively skewed and may be leptokurtic inefficiency also leads to amplification in price of small changes in news relative to informationally efficient benchmarks public information affects the nature of unrevealed private information and the informational inefficiency of prices asset prices may be lower higher with good bad public information

elimination and selection by aspects in health choice experiments prioritising health service innovations priorities for public health innovations are typically not considered equally by all members of the public when faced with a choice between various innovation options it is therefore possible that some respondents eliminate and or select innovations based on certain characteristics this paper proposes a flexible method for exploring and accommodating situations where respondents exhibit such behaviours whilst addressing preference heterogeneity we present an empirical case study on the public s preferences for health service innovations we show that allowing for elimination by aspects and or selection by aspects behavioural rules leads to substantial improvements in model fit and importantly has implications for willingness to pay estimates and scenario analysis

impact of ex ante hypothetical bias mitigation methods on attribute non attendance in choice experiments in this article we use survey data from nigeria on consumers preferences for organic products to investigate the impact of ex ante hypothetical bias mitigation methods cheap talk and honesty priming on respondents attribute non attendance we employ a framework that allows us to jointly examine the response to the stated choice component and the response to the attribute processing questions while avoiding the potential endogeneity bias and measurement error problems arising from some attribute non attendance methods our results show that the incidence of attribute non attendance varies across the treatments in general with significant difference in attribute non attendance rates between respondents exposed to the mitigation strategies honesty priming and cheap talk and the baseline group we also find that the low willingness to pay values for the honesty priming task appear to correspond with the lowest attribute non attendance rates reported for all the attributes especially price and might reflect a more realistic valuation of the attributes

erratum wealth information acquisition and portfolio choice a correction there is an error in my 2004 paper wealth information acquisition and portfolio choice this note shows how to correct it by adjusting the hypotheses of the model specifically it assumes that agents learn about the stock s mean payoff rather than about its realization all the conclusions of the paper remain valid there is a mistake in the derivation of agents unconditional expected utility in wealth information acquisition and portfolio choice review of financial studies 17 3 2004 pages 879 914 some formulas need to be corrected and some assumptions adjusted but all the conclusions of the paper remain valid in particular it remains the case that wealthier investors collect more information and that as a result they hold a larger fraction of their wealth in stocks even though their relative risk aversion is not lower the unconditional expected utility is approximated using a taylor series expansion in which higher order terms are dropped in fact these terms cannot be neglected under the payoff structure postulated in the paper as a result the demand for information cannot be evaluated for arbitrary preferences in this note we offer a solution to the issue which relies on a slight modification of the stock s payoff structure and supports all the conclusions of the paper 1 the problem the expression for the conditional expected utility ej u w2j fj stated on page 906 is correct however equation 12 obtained by taking its unconditional expectation is not to see why we rewrite ej u w2j fj as ej u w2j fj u w0j u w0j ej w fj 1 2 u w0j ej w 2 fj o z 1

auctions actions and the failure of information aggregation we study a market where k identical and indivisible objects are allocated using a uniform price auction where n k bidders each demand one object before the auction each bidder receives an informative but imperfect signal about the state of the world the good that is auctioned is a common value object for the bidders and a bidder s valuation for the object is determined jointly by the state of the world and an action that he chooses after winning the object but before he observes the state we show that there are equilibria where the auction price is completely uninformative about the state of the world and aggregates no information even in an arbitrarily large auction in the equilibrium that we construct because prices do not aggregate information agents have strict incentives to acquire costly information before they participate in the market also market statistics other than price such as the amount of rationing and bid distributions contain extra information about the state our findings sharply contrast with past work which shows that large auctions aggregate information when there is no ex post action

on the possibility of informationally efficient markets this paper presents conditions for a resolution of the grossman stiglitz paradox of informationally efficient markets we display a market with asymmetric information where a privately revealing equilibrium obtains in a competitive framework and where incentives to acquire information are preserved as long as the correlation in traders valuations is not too large the equilibrium is efficient and the problems associated with fully revealing rational expectations equilibria are precluded without resorting necessarily to noise traders the robustness of the results to general information structures is established and the effect of market power is examined in a large market approximation to the competitive economy the model is applied to explain changes in bidding behavior in central bank liquidity auctions in the crisis period jel d82 d84 g14 e59

price inference in small markets this paper investigates the effects of market size on the ability of price to aggregate traders private information to account for heterogeneity in correlation of trader values a gaussian model of double auction is introduced that departs from the standard information structure based on a common fundamental shock the paper shows that markets are informationally efficient only if correlations of values coincide across all bidder pairs as a result with heterogeneously interdependent values price informativeness may not increase monotonically with market size as a necessary and sufficient condition for the monotonicity price informativeness increases with the number of traders if the implied reduction in the absolute value of an average correlation statistic of an information structure is sufficiently small

information aggregation in dynamic markets with strategic traders this paper studies information aggregation in dynamic markets with a finite number of partially informed strategic traders it shows that for a broad class of securities information in such markets always gets aggregated trading takes place in a bounded time interval and in every equilibrium as time approaches the end of the interval the market price of a separable security converges in probability to its expected value conditional on the traders pooled information if the security is non separable then there exists a common prior over the states of the world and an equilibrium such that information does not get aggregated the class of separable securities includes among others arrow debreu securities whose value is 1 in one state of the world and 0 in all others and additive securities whose value can be interpreted as the sum of traders signals

incorporating discontinuous preferences into the analysis of discrete choice experiments data from a discrete choice experiment on improvements of rural landscape attributes are used to investigate the implications of discontinuous preferences on willingness to pay estimates using a multinomial error component logit model we explore differences in scale and unexplained variance between respondents with discontinuous and continuous preferences and condition taste intensities on whether or not each attribute was considered by the respondent during the evaluation of alternatives results suggest that significant improvements in model performance can be achieved when discontinuous preferences are accommodated in the econometric specification and that the magnitude and robustness of the willingness to pay estimates are sensitive to discontinuous preferences

inferred vs stated attribute non attendance in choice experiments a study of doctors prescription behaviour abstract it is increasingly recognised that respondents to choice experiments employ heuristics such as attribute non attendance ana to simplify the choice tasks this paper develops an econometric model which incorporates preference heterogeneity among respondents and allows the probability of non attendance to depend on the respondents stated non attendance we find evidence that stated ana is a useful indicator of the prevalence of non attendance in the data contrary to previous papers in the literature we find that estimates of marginal rates of substitution derived from models which account for ana are similar to the standard logit estimates

more hands more power estimating the impact of immigration on output and technology choices using early 20th century us agriculture can shifts in output mix or technologies attenuate the impact of immigration on wages we explore this using immigration induced changes in relative labor supply at the county level in us censuses of agriculture in early 20th century an increase in labor supply induced a shift away from capital intensive crops and a reduction in farm size crop mix adjustments were more likely in counties less specialized in a given crop while adjustments in technological and organization changes were more marked in the rest suggestive evidence indicates that crop mix adjustments but not organizational changes were sufficient to limit wage impacts

asymmetric price movements and borrowing constraints a rational expectations equilibrium model of crises contagion and confusion this study proposes a rational expectations equilibrium model of crises and contagion in an economy with information asymmetry and borrowing constraints consistent with empirical observations the model finds 1 crises can be caused by small shocks to fundamentals 2 market return distributions are asymmetric and 3 correlations among asset returns tend to increase during crashes the model also predicts 1 crises and contagion are likely to occur after small shocks in the intermediate price region 2 the skewness of asset price distributions increases with information asymmetry and borrowing constraints and 3 crises can spread through investor borrowing constraints

a discrete choice model with endogenous attribute attendance abstract this paper develops a discrete choice model in which the decision to consider an attribute in the choice process is modelled endogenously in an application to patients choice of general practitioner it is found that the proposed model outperforms the standard logit model in terms of goodness of fit and produces substantially different estimates of willingness to pay

the enduring impact of the american dust bowl short and long run adjustments to environmental catastrophe the 1930 s american dust bowl was an environmental catastrophe that greatly eroded sections of the plains analyzing new data collected to identify low medium and high erosion counties the dust bowl is estimated to have immediately substantially and persistently reduced agricultural land values and revenues during the depression and through at least the 1950 s there was limited reallocation of farmland from activities that became relatively less productive agricultural adjustments such as reallocating land from crops to livestock recovered only 14 to 28 of the initial agricultural cost the economy adjusted predominately through migration rather than through capital inows and increased industry

information acquisition price informativeness and welfare abstract we consider the market for a risky asset with heterogeneous valuations private information that agents have about their own valuation is reflected in the equilibrium price we study the learning externalities that arise in this setting and in particular their implications for price informativeness and welfare when private signals are noisy so that agents rely more on the information conveyed by prices discouraging information gathering may be pareto improving complementarities in information acquisition can lead to multiple equilibria

social interaction and stock market participation we propose that stock market participation is influenced by social interaction in our model any given social investor finds the market more attractive when more of his peers participate we test this theory using data from the health and retirement study and find that social households those who interact with their neighbors or attend church are substantially more likely to invest in the market than non social households controlling for wealth race education and risk tolerance moreover consistent with a peer effects story the impact of sociability is stronger in states where stock market participation rates are higher

first order risk aversion heterogeneity and asset market outcomes we examine a wide range of two date economies populated by heterogeneous agents with the most common forms of nonexpected utility preferences used in finance and macroeconomics we demonstrate that the risk premium and the risk free rate in these models are sensitive to ignoring heterogeneity this follows because of endogenous withdrawal by nonexpected utility agents from the market for the risky asset this finding is important precisely because these alternative preferences have frequently been proposed as possible resolutions to various asset pricing puzzles and they have all been examined exclusively in a representative agent framework the well documented shortcomings of asset pricing models based in part on the expected utility eu hypothesis has motivated a large and rapidly grow ing set of pricing models that incorporate nonexpected utility preferences the pricing implications of these models in the existing literature have been based exclusively on the assumption of a single representative agent ra who prices assets using the aggregate endowment as the consumption process while ag gregation is well understood in the standard eu setting see constantinides 1982 it can be more complicated when some or all agents do not have eu we provide a simple and intuitive examination of the asset pricing implications of heterogeneity for the most commonly used alternatives to eu our primary finding is that the risk premium and the risk free rate are sensitive to ignoring heterogeneity in all of the simple two date non eu models that we examine we compare the prices in a model with two agent types to the prices in a model with a single representative agent who has a wealth weighted average of the utility parameters in the two agent economy the economies are otherwise identical for example they have the same endowment process market structure etc it is common for the single agent model to overstate the equity premium often by as much as 100 or more of the value in the two agent model and to understate the level of the risk free rate often by as much as 20 of the value in the two agent model

ambiguity and nonparticipation the role of regulation we investigate the implications of ambiguity aversion for performance and regulation of markets in our model agents decision making may incorporate both risk and ambiguity and we demonstrate that nonparticipation arises from the rational decision by some traders to avoid ambiguity in equilibrium these participation decisions affect the equilibrium risk premium and distort market performance when viewed from the perspective of traditional asset pricing models we demonstrate how regulation particularly regulation of unlikely events can moderate the effects of ambiguity thereby increasing participation and generating welfare gains our analysis demonstrates how legal systems affect participation in financial markets through their influence on ambiguity the author 2009 published by oxford university press on behalf of the society for financial studies all rights reserved for permissions please e mail journals permissions oxfordjournals org oxford university press

releasing the trap a method to reduce inattention bias in survey data with application to u s beer taxes this study uses discrete choice experiments to explore the efficacy of prompts targeted at reducing inattention bias upon receiving feedback inattentive respondents are given the opportunity to reanswer a so called trap question that checks for attentiveness we find that individuals who miss trap questions and do not correctly revise their responses have significantly different choice patterns as compared to individuals who correctly answer the trap question adjusting for these inattentive responses has a substantive impact on policy impacts results based on attentive participant responses indicate that a minimum beer price would have to be substantial to substantially reduce beer demand jel c83 q18 q51

informed speculation with imperfect competition competitive rational expectations models have the unsatisfactory property dubbed the schizophrenia problem by hellwig that each trader takes the equilibrium price as given despite the fact that he influences that price an examination of information aggregation in a non competitive rational expectations model using a nash equilibrium in demand functions shows that the schizophrenia problem is avoided by having each trader take into account the effect his demand has on the equilibrium price given a distribution of private information across traders prices reveal less information than in the competition equilibrium and prices no longer become fully informative in the limit as noise trading vanishes or as traders become risk neutral with small traders the model may become one of monopolistic competition not perfect competition in contrast to the competitive model a reasonable model of endogenous acquisition of costly private information is obtained even when traders are risk neutral

how do respondents process stated choice experiments attribute consideration under varying information load the popularity of stated choice sc experiments has produced many design strategies in which researchers use increasingly more complex choice settings to study choice behaviour when the amount of information to assess increases we wonder how an individual handles such information in making a choice defining the amount of information as the number of attributes associated with each choice set we investigate how this information is processed as we vary its complexity four ordered heterogeneous logit models are developed each for an sc design based on a fixed number of attributes in which the dependent variable defines the number of attributes that are ignored we find that the degree to which individuals ignore attributes is influenced by the dimensionality of the sc experiment the deviation of attribute levels from an experienced reference alternative the use of adding up attributes where feasible the number of choice sets evaluated and the personal income of the respondent the empirical evidence supports the view that individuals appear to adopt a range of coping strategies that are consistent with how they process information in real markets and that aligning choice complexity with the amount of information to process is potentially misleading relevancy is what matters copyright 2006 john wiley sons ltd

the effect of low skilled immigration on u s prices evidence from cpi data i exploit the large variation across u s cities and through time in the relative size of the low skilled immigrant population to estimate the causal effect of immigration on prices of nontraded goods and services using an instrumental variables strategy i find that at current immigration levels a 10 percent increase in the share of low skilled immigrants in the labor force decreases the price of immigrant intensive services such as housekeeping and gardening by 2 percent wage equations suggest that lower wages are a likely channel through which these effects take place however wage effects are significantly larger for low skilled immigrants than for low skilled natives implying that the two are imperfect substitutes

liquidity regimes and optimal dynamic asset allocation abstract we solve a portfolio choice problem when expected returns covariances and trading costs follow a regime switching model the optimal policy trades towards an aim portfolio given by a weighted average of the conditional mean variance efficient portfolios in all future states the trading speed is higher in more persistent riskier and higher liquidity states it can be optimal to overweight low sharpe ratio assets such as treasury bonds because they remain liquid even in crisis states we illustrate our methodology by constructing an optimal us equity market timing portfolio based on an estimated regime switching model and on trading costs estimated using a large order institutional trading data set

learning and price discovery in a search market we introduce learning into an otherwise standard two sided search and bargaining market there is uncertainty about the price distribution due to uncertainty about an underlying exogenous state of relative demand in the high state buyers are on the long side otherwise they are on the short side in equilibrium prices are on average higher in the high state individual agents learn about the distribution while searching agents typically start out by experimenting with a tough bargaining position buyers may initially insist on a low price and sellers on a high price after successive failures to trade agents become increasingly pessimistic about the market conditions and soften their bargaining stance when frictions are small equilibrium transaction prices are approximately market clearing despite aggregate demand being unknown thus the search and bargaining procedure enables price discovery in a decentralized market

generic existence of completely revealing equilibria for economies with uncertainty when prices convey information conditions which imply the existence of strict rational expectations equilibria for most static pure exchange economies where prices convey information about the state of the world are analyzed information is aggregated and transmitted by prices because agents have different initial information and maximize the conditional expectation of state dependent utility functions major results state that if with probability one agents characteristics do not vary too much as the state of the world varies then generically there exist equilibrium price functions which reveal all initial information more precisely if the support of the image measure is contained in a compact c1 manifold satisfying some technical conditions which is of sufficiently low dimension relative to the number of commodities then existence of completely revealing equilibria is generic any economy satisfying these assumptions can be approximated by a sequence of economies which also obey these assumptions and have completely revealing equilibrium price functions slight perturbations do not destroy the existence property

people and machines a look at the evolving relationship between capital and skill in manufacturing 1860 1930 using immigration shocks abstract this paper estimates the elasticity of substitution between capital and skill in manufacturing using immigration induced variation in skill mix across u s counties between 1860 and 1930

information linkages and correlated trading in a market with informationally connected traders the dynamics of volume price informativeness price volatility and liquidity are severely affected by the information linkages every trader experiences with his peers we show that in the presence of information linkages among traders volume and price informativeness increase moreover we find that information linkages improve or damage market depth and lower or boost the traders profits according to whether these linkages convey positively or negatively correlated signals finally our model predicts patterns of trade correlation consistent with those identified in the empirical literature trades generated by neighbor traders are positively correlated and trades generated by distant traders are negatively correlated

insider trading in a rational expectations economy it is often argued that efficiency considerations require society to freely permit insider trading in this article an opposing efficiency argument is formalized the model incorporates an investment stage followed by a trading stage if outsiders expect insiders to take advantage of them in trading outsiders will reduce their investment the insiders loss from this diminished investor confidence may more than offset their trading gains consequently a prohibition on insider trading may effect a pareto improvement insiders are made better off if they can precommit not to trade on their privileged information govemment regulation accomplishes exactly this jel 022 026 313 the traditional rationale articulated for insider trading regulation and other securities law is that such rules promote confidence in markets indeed president franklin d roosevelt justified the first major u s securities legislation by saying it should give impetus to honest dealing in securities and thereby bring back public confidence similar language is still invoked half a century later in connection with enforcement efforts against insider trading and in proposals for tightened stock

redistribution and market efficiency an experimental study abstract we study the interaction between competitive markets and income redistribution that reallocates unequal pre tax market incomes away from the rich to the poor majority in one setup participants earn their income by trading in a double auction da with exogenous zero or full redistribution in another setup after trading they vote on redistributive tax policies in a majoritarian election with two competing candidates this results in virtually full redistribution even when participants have the opportunity to influence taxes by transferring money to the candidates we find that the high redistribution reduces trading efficiency but not as much as predicted if market participants trade randomly this is because rather than capitulating to the much lower trading incentives many participants respond to redistribution by asking and bidding more conservatively in the da and in this way help to prevent further efficiency losses

dealing with ignored attributes in choice experiments on valuation of sweden s environmental quality objectives using a choice experiment this paper investigates how swedish citizens value three environmental quality objectives in addition a follow up question is used to investigate whether respondents ignored any attributes when responding the resulting information is used in model estimation by restricting the individual parameters for the ignored attributes to zero when taking the shares of respondents who took both the environmental and the cost attributes 52 69 of the respondents into account then the wtp for each attribute changes if the respondents who ignored the attributes have a zero wtp at the same time we find evidence that not all respondents who claimed to have ignored an attribute really did however the most commonly ignored non monetary attributes always have the lowest rankings in terms of wtp across all three environmental objectives thus our results show that instead of ignoring attributes completely respondents seem to put less weight on the attributes they claimed to have ignored

business as usual market crashes and wisdom after the fact the authors present a three stage model of market dynamics in the first stage routine behavior tends to keep information of common interest trapped in private hands in the second stage private information reaches a threshold that triggers some agents to alter their behavior these actions release information to the market the final stage involves the market s response to this news as other participants react to the initial departure from routine behavior the authors present an application to industry investment they also outline applications to the international debt crisis to bank runs and to political upheavals copyright 1994 by american economic association

gps shifting agencies in choice of treatment earlier studies have shown that general practitioners gps prescription choices are influenced by effect patient costs and costs to society patient attitude and own experience this study builds on this knowledge and explores how prescription behaviour is affected when choices are made in different contexts where the conflicting roles as agents for the patient and agents for society are stressed a total of 309 danish gps were randomly allocated to one of three versions of a web based questionnaire which included a discrete choice experiment mixed logit models in willingness to pay wtp space were estimated with and without accounting for stated attribute non attendance results show that the gp s role as agent for his patients is clearly strengthened in the presence of national recommendations in contrast when recommendations are not present and when gps face a patient who is currently taking an expensive albeit effective medication the gp takes on his role as agent for society we find no evi

an introduction to the theory of rational expectations under asymmetric information every good economics textbook contains the cliche that market prices provide signals which facilitate the allocation of resources to their best use in a world not subject to random shocks consumers and producers when faced with competitive prices need look no further than their own preferences or production technology to be able to make a decision they need give no thought to the tastes endowments or technology of other agents however in a world subject to random shocks this is no longer the case agents are faced with the problem of forecasting future states of nature and more importantly of forecasting the impact of these states on the actions of other agents rational expectations theories provide a model of how agents make those forecasts in a world subject to random shocks it will be the case that agents acquire or at least attempt to acquire information about the future realization of the shocks it will in general be the case that different agents have access to different information the fact that information is dispersed throughout the economy has the potential to cause a misallocation of resources relative to what would be the case if all agents knew everything an efficient allocation of resources will in general require the transfer of information from consumers who have some information about their future demands to producers who can take current actions to mitigate avoidable scarcities or surpluses though many classical and neo classical writers emphasize the informational role of prices the standard marshallian or walrasian model of competitive equilibrium does not involve prices transferring information across traders the purpose of this paper is to show that rational expectations models are radically different from walrasian models in an economy where traders have diverse information this is demonstrated by showing that unlike what occurs in a walrasian equilibrium of an economy with heterogeneous information if there is a complete set of insurance markets and utility is additively separable over time then there exists a rational expectations equilibrium which gives consumers the same allocation as if each consumer has access to all of the economy s information this implies that under the above assumptions a central planner with all the economy s information could not pareto dominate the competitive allocation achieved when traders have diverse information and rational expectations this paper makes no attempt to survey the literature on rational expectations the reader is referred to shiller 1978 barro 1981 for a survey of macroeconomics and rational expectations and radner 1980 for a survey of the microeconomics and mathematical theory of rational expectations this paper will however try to outline the evolution of the rational expectations concept from a notion of optimal forecasting to a virtually complete departure from the walrasian model of equilibrium the rest of this section is devoted to a discussion of pre rational expectations ideas

manipulation and the allocational role of prices it is commonly believed that prices in secondary financial markets play an important allocational role because they contain information that facilitates the efficient allocation of resources this paper identifies a limitation inherent in this role of prices it shows that the presence of a feedback effect from the financial market to the real value of a firm creates an incentive for an uninformed trader to sell the firm s stock when this happens the informativeness of the stock price decreases and the beneficial allocational role of the financial market weakens the trader profits from this trading strategy partly because his trading distorts the firm s investment we therefore refer to this strategy as manipulation we show that trading without information is profitable only with sell orders driving a wedge between the allocational implications of buyer and seller initiated speculation and providing justification for restrictions on short sales

information quality and options microstructure researchers have long understood that information quality has an effect on price formation in the underlying asset market however option researchers have largely ignored the fact that information quality might also impact the options market this article characterizes the nature of the impact by showing how option prices and implied volatility levels are related to the forward looking information quality path this result follows from a noisy rational expectations model that abandons the normal distribution in favor of the gamma distribution but maintains the standard assumption of exponential utility thus the new model bridges the gap between the microstructure literature that relies so heavily on the normal exponential framework and the options literature that relies exclusively on models that are consistent with the limited liability of stock prices the model s tractability allows for a robustness check against the standard framework and provides a viable setting for analyzing the empirical implications of information quality for the options market jel d8 gl

asymmetric information nonadditive expected utility and the information revealed by prices an example i develop a simple example of a model in which agents have asymmetric information and preferences that are represented by a nonadditive expected utility function the a priori uninformed agent after observing the equilibrium price has conditional beliefs that remain nonadditive then even when the equilibrium price function is fully revealing i e one to one it may be worth while for an a priori uninformed agent to buy redundant private information if he is more confident in that information than in that revealed by the price system

wealth information acquisition and portfolio choice i solve with an approximation a grossman stiglitz economy under general preferences thus allowing for wealth effects because information generates increasing returns decreasing absolute risk aversion in conjunction with the availability of costly information is sufficient to explain why wealthier households invest a larger fraction of their wealth in risky assets one no longer needs to resort to decreasing relative risk aversion an empirically questionable assumption furthermore i show how to distinguish empirically between these two explanations finally i find that the availability of costly information exacerbates wealth inequalities copyright 2004 oxford university press

market liquidity hedging and crashes in the absence of significant news hedging strategies were blamed for the stock market crash of october 1987 but traditional models cannot explain how a relatively small amount of selling could cause so large a price drop the authors develop a rational expectations model in which prices play an important role in shaping expectations markets are much less liquid in their model than in traditional models discontinuities or crashes can occur even with relatively little hedging the model is consistent with theories as disparate as keynes beauty contest insights and thom s catastrophe analysis and suggests means to reduce volatility copyright 1990 by american economic association

are fast responses more random testing the effect of response time on scale in an online choice experiment scepticism over stated preference surveys conducted online revolves around the concerns over professional respondents who might rush through the questionnaire without sufficiently considering the information provided to gain insight on the validity of this phenomenon and test the effect of response time on choice randomness this study makes use of a recently conducted choice experiment survey on ecological and amenity effects of an offshore windfarm in the uk the positive relationship between self rated and inferred attribute attendance and response time is taken as evidence for a link between response time and cognitive effort subsequently the generalised multinomial logit model is employed to test the effect of response time on scale which indicates the weight of the deterministic relative to the error component in the random utility model results show that longer response time increases scale i e decreases choice randomness this positive scale effect of response time is further found to be non linear and wear off at some point beyond which extreme response time decreases scale while response time does not systematically affect welfare estimates higher response time increases the precision of such estimates these effects persist when self reported choice certainty is controlled for implications of the results for online stated preference surveys and further research are discussed