optimizing multinomial logit profit functions the multinomial logit model is a standard approach for determining the probability of purchase in product line problems when the purchase probabilities are multiplied by product contribution margins the resulting profit function is generally nonconcave because of this standard nonlinear search procedures may terminate at a local optimum which is far from the global optimum we present a simple procedure designed to alleviate this problem the key idea of this procedure is to find a path of prices from the global optimum of a related but concave logit profit function to the global optimum of the true but nonconcave logit profit function

the impact of a financial transaction tax on stylized facts of price returns evidence from the lab as the introduction of financial transaction taxes is increasingly discussed by political leaders we explore possible consequences such taxes could have on markets here we examine how stylized facts namely fat tails and volatility clustering are affected by different tax regimes in laboratory experiments we find that leptokurtosis of price returns is highest and clustered volatility is weakest in unilaterally taxed markets where tax havens exist instead tails are slimmest and volatility clustering is strongest in tax havens when an encompassing financial transaction tax is levied stylized facts hardly change compared to a scenario with no tax on all markets

interbank market liquidity and central bank intervention we develop a simple model of the interbank market where banks trade a long term safe asset when there is a lack of opportunities for banks to hedge idiosyncratic and aggregate liquidity shocks the interbank market is characterized by excessive price volatility in such a situation a central bank can implement the constrained efficient allocation by using open market operations to fix the short term interest rate it can be constrained efficient for banks to hoard liquidity and stop trading with each other if there is sufficient uncertainty about aggregate liquidity demand compared to idiosyncratic liquidity demand

constrained assortment optimization for the nested logit model we study assortment optimization problems where customer choices are governed by the nested logit model and there are constraints on the set of products offered in each nest under the nested logit model the products are organized in nests each product in each nest has a fixed revenue associated with it the goal is to find a feasible set of products i e a feasible assortment to maximize the expected revenue per customer we consider cardinality and space constraints on the offered assortment which limit the number of products and the total space consumption of the products offered in each nest respectively we show that the optimal assortment under cardinality constraints can be obtained efficiently by solving a linear program the assortment optimization problem under space constraints is np hard we show how to obtain an assortment with a performance guarantee of 2 under space constraints this assortment also provides a performance guarantee of 1 1 when the space requirement of each produc

an experimental investigation of the patterns of international trade this study is the first attempt to create and study a laboratory economy with some of the prominent features of an international economic system the concept of multiple countries in which each country has its own technology preferences and resource endowments is introduced and operationalized the questions posed in the study are related to the law of comparative advantage factor price equalization terms of trade efficiency in production and exchange as guided by multiple and interacting markets and the effects of tariffs on international transactions the study builds on previous work in the experimental study of general equilibrium phenomena

a nonparametric approach to modeling choice with limited data choice models today are ubiquitous across a range of applications in operations and marketing real world implementations of many of these models face the formidable stumbling block of simply identifying the right model of choice to use because models of choice are inherently high dimensional objects the typical approach to dealing with this problem is positing a priori a parametric model that one believes adequately captures choice behavior this approach can be substantially suboptimal in scenarios where one cares about using the choice model learned to make fine grained predictions one must contend with the risks of mis specification and overfitting underfitting thus motivated we visit the following problem for a generic model of consumer choice namely distributions over preference lists and a limited amount of data on how consumers actually make decisions such as marginal information about these distributions how may one predict revenues from offering a particular assortment of choices an outcome of our investigation is a nonparametric approach in which the data automatically select the right choice model for revenue predictions the approach is practical using a data set consisting of automobile sales transaction data from a major u s automaker our method demonstrates a 20 improvement in prediction accuracy over state of the art benchmark models this improvement can translate into a 10 increase in revenues from optimizing the offer set we also address a number of theoretical issues among them a qualitative examination of the choice models implicitly learned by the approach we believe that this paper takes a step toward automating the crucial task of choice model selection this paper was accepted by yossi aviv operations management

the exponomial choice model a new alternative for assortment and price optimization we investigate the use of a canonical version of a discrete choice model due to daganzo 1979 daganzo c 1979 multinomial probit the theory and its application to demand forecasting academic press new york in optimal pricing and assortment planning in contrast to multinomial and nested logit the prevailing choice models used for optimizing prices and assortments this model assumes a negatively skewed distribution of consumer utilities an assumption we motivate by conceptual arguments as well as published work the choice probabilities in this model can be derived in closed form as an exponomial a linear function of exponential terms the pricing and assortment planning insights we obtain from the exponomial choice ec model differ from the literature in two important ways first the ec model allows variable markups in optimal prices that increase with expected utilities second when prices are exogenous the optimal assortment may exhibit leapfrogging in prices i e a product can be s

competitive behavior in market games evidence and theory we explore whether competitive outcomes arise in an experimental implementation of a market game introduced by shubik 1972 market games obtain pareto inferior strict nash equilibria in which some markets are closed we find that subjects do not coordinate on autarkic nash equilibria but favor more efficient nash equilibria in which all markets are open as the number of subjects participating in the market game increases the nash equilibrium they achieve approximates the associated walrasian equilibrium of the underlying economy motivated by these findings we investigate theoretically whether evolutionary forces lead to walrasian outcomes in market games we introduce a strong version of evolutionary stable strategies sess f orfinite populations our concept requires stability against deviations by coalitions of agents a small coalition of trading agents is sufficient for pareto improving trade to be generated in addition provided that agents lack market power nash equilibria corresponding to approximate competitive outcomes constitute the only approximate sess

inefficient investment waves we show that firms individually optimal liquidity management results in socially inefficient boom and bust patterns financially constrained firms decide on the level of their liquid resources facing cash flow shocks and time varying investment opportunities firms liquidity management decisions generate simultaneous waves in aggregate cash holdings and investment even if technology remains constant these investment waves are not constrained efficient in general because the social and private value of liquidity differs the resulting pecuniary externality affects incentives differentially depending on the state of the economy and often overinvestment occurs during booms and underinvestment occurs during recessions in general policies intended to mitigate underinvestment raise prices during recessions making overinvestment during booms worse however a well designed price support policy will increase welfare in both booms and recessions

leverage cycles and the anxious economy ing opportunities for emerging economies their access to international markets has turned out to be very volatile with frequent periods of market closures even worse as we will show emerging economies with sound fundamentals are the ones that issue less debt during these closures the goal of this paper is to present a theory of asset pricing that will shed light on the problems of emerging assets like emerging markets that are not yet mature enough to be attractive to the general public their marginal buyers are liquidity constrained investors with small wealth relative to the whole economy who are also marginal buyers of other risky assets we will use our theory to argue that the periodic problems faced by emerging asset classes are sometimes symptoms of what we call a global anxious economy rather than of their own fundamental weaknesses

rational expectations and the aggregation of diverse information in laboratory security markets the idea that markets might aggregate and disseminate information and also resolve conflicts is central to the literature on decentralization hurwicz 1972 and rational expectations lucas 1972 we report on three series of experiments all of which were predicted to have performed identically by the theory of rational expectations in two of the three series one in which participants trade a complete set of arrow debreu securities and a second in which all participants have identical preferences double auction trading leads to efficient aggregation of diverse information and rational expectations equilibrium failure of the third series to exhibit such convergence demonstrates the importance of market institutions and trading instruments in achievement of equilibrium

market for information experimental evidence predictions of the noisy rational expectations equilibrium ree model are found to be relatively accurate for both asset and information markets in the laboratory when information about an asset s uncertain dividend is sold to a fixed number of highest bidders prices allocations efficiency and distribution of profit predictions of the full revelation ree model in the asset market dominate the predictions of the walrasian model demand for information shifts to the left and its price declines close to zero when the price of information is fixed at a relatively high level the number of informed agents and the informativeness of the asset market tends to adjust to permit the informed agents to recover their investment in information

experiments on percolation of information in dark markets in dark markets order submissions are bilateral and transaction prices are known only to the trading counterparties here we study to what extent the information aggregation theory proposed by duffie and collaborators predicts outcomes in a laboratory version of such markets we find that prices aggregate the available information but not in the strict sense of the theory where prices converge exponentially fast to average private signals prices instead fluctuate within bands around this average the band widths reflect in the best case the precision of the average signal and otherwise the precision of a single private signal

credit constraints in general equilibrium experimental results our work attempts to investigate the influence of credit tightness orexpansion on activity and relative prices in a multimarket set up we report on somedouble auction two market experiments where subjects had to satisfy an inequalityinvolving the use of credit the experiments display two regimes characterizedby high and low credit availability the critical value of credit at the commonboundary of the two regimes has a compelling interpretation as the maximal credituse at the arrow debreu equilibrium of the abstract economy naturally associatedto our experimental environment our main results are that changes in theavailability of credit a have minor and unsystematic effects on quantitiesand relative prices in the high credit regime b have substantial effects bothon quantities and relative prices in the low credit regime

an experimental test of an optimal growth model this paper describes the design and behavior of an experimental economy with the structure of the ramsey cass koopmans model of optimal growth the experiment includes three different implementations of the model a decentralized implementation with multiple agents and a market for capital a treatment where individual subjects are placed in the role of social planners and a treatment where the social planner consists of five agents making a joint decision the findings highlight the role of market institutions in facilitating convergence to the optimal steady state jel c91 c92 o40

assortment optimization under variants of the nested logit model we study a class of assortment optimization problems where customers choose among the offered products according to the nested logit model there is a fixed revenue associated with each product the objective is to find an assortment of products to offer so as to maximize the expected revenue per customer we show that the problem is polynomially solvable when the nest dissimilarity parameters of the choice model are less than one and the customers always make a purchase within the selected nest relaxing either of these assumptions renders the problem np hard to deal with the np hard cases we develop parsimonious collections of candidate assortments with worst case performance guarantees we also formulate a convex program whose optimal objective value is an upper bound on the optimal expected revenue thus we can compare the expected revenue provided by an assortment with the upper bound on the optimal expected revenue to get a feel for the optimality gap of the assortment by using this approach our computational experiments test the performance of the parsimonious collections of candidate assortments that we develop

collateral constraints and the law of one price an experiment we test the asset pricing implications of collateralized borrowing that is of using assets as collateral to borrow money in the laboratory to this purpose we develop a general equilibrium model with collateral constraints amenable to laboratory implementation and gather experimental data in the laboratory assets that can be leveraged fetch higher prices than assets that cannot even though assets payoffs are identical in all states of the world collateral value therefore creates deviations from the law of one price the spread between collateralizeable and noncollateralizeable assets is significant and quantitatively close to theoretical predictions

an experiment on the efficiency of bilateral exchange under incomplete markets abstract we test in a controlled laboratory environment whether traders in a bilateral exchange internalize the impact of their actions on market prices better than in a large market in this model traders choose asset holdings constrained by a technology frontier next each trader experiences a random shock which makes only one type of asset profitable in a general equilibrium environment with incomplete markets this leads to pecuniary externalities because traders increase scarce asset holdings beyond what is socially optimal this behavior is especially exacerbated in large experimental markets as traders fail to internalize the impact of their actions on prices we find that when markets are incomplete a bilateral exchange can slightly mitigate the extent of pecuniary externalities and weakly increase welfare

revenue management under a general discrete choice model of consumer behavior customer choice behavior such as buy up and buy down is an important phenomenon in a wide range of revenue management contexts yet most revenue management methodologies ignore this phenomenon or at best approximate it in a heuristic way in this paper we provide an exact and quite general analysis of this problem specifically we analyze a single leg reserve management problem in which the buyers choice behavior is modeled explicitly the choice model is very general simply specifying the probability of purchase for each fare product as a function of the set of fare products offered the control problem is to decide which subset of fare products to offer at each point in time we show that the optimal policy for this problem has a quite simple form namely it consists of identifying an ordered family of efficient subsets s 1 s m and at each point in time opening one of these sets s k where the optimal index k is increasing in the remaining capacity x and decreasing in the remaining time that is the more capacity or less time available the further the optimal set is along this sequence we also show that the optimal policy is a nested allocation policy if and only if the sequence of efficient sets is nested that is s 1 s 2 s m moreover we give a characterization of when nesting by fare order is optimal we also develop an estimation procedure for this setting based on the expectation maximization em method that jointly estimates arrival rates and choice model parameters when no purchase outcomes are unobservable numerical results are given to illustrate both the model and estimation procedure

historical property rights sociality and the emergence of impersonal exchange in long distance trade this laboratory experiment explores the extent to which impersonal exchange emerges from personal exchange with opportunities for long distance trade we design a three commodity production and exchange economy in which agents in three geographically separated villages must develop multilateral exchange networks to import a good only available abroad for treatments we induce two distinct institutional histories to investigate how past experience with prop erty rights affects the evolution of specialization and exchange we find that a history of unenforced property rights hinders our subjects ability to develop the requisite personal social arrangements to support specialization and effec tively exploit impersonal long distance trade jel c90 d23 d5 p 4

pecuniary externalities in economies with financial frictions this article characterizes the efficiency properties of competitive economies with financial constraints in which phenomena such as fire sales and financial amplification may arise we show that financial constraints lead to two distinct types of pecuniary externalities distributive externalities that arise from incomplete insurance markets and collateral externalities that arise from price dependent financial constraints for both types of externalities we identify three sufficient statistics that determine optimal taxes on financing and investment decisions to implement constrained efficient allocations we also show that fire sales and financial amplification are neither necessary nor sufficient to generate inefficient pecuniary externalities we demonstrate how to employ our framework in a number of applications whereas collateral externalities generally lead to over borrowing the distortions from distributive externalities may easily flip sign leading to either under or over borrowing both types of externalities may lead to under or over investment

time varying threshold cointegration and the law of one price a theoretical model of the law of one price which allows for seasonality in transaction costs and supply and demand conditions between markets is developed bivariate three regime threshold vector error correction models are applied to natural gas markets to examine seasonality in threshold levels results indicate that there are nonlinear adjustments to the law of one price in seven pair wise markets chicago is used as the base market in the natural gas sector dynamic threshold effects relative to the chicago market vary depending on season geographical location and whether the market is an excess producing or consuming market

price dynamics in general equilibrium experiments general equilibrium ge theory faces several related challenges classical theories of out of equilibrium adjustment are intuitive but implausibly centralized further standard restrictions on individual preferences place little structure on aggregate excess demand functions amongst other issues this fact implies that economies can be unstable under classical dynamics and thus instability appears to be an unavoidable feature of ge theory this paper recounts laboratory studies of ge environments which reveal that classical theories of dynamics do in fact organize market activity surprisingly well these experiments suggest that the walrasian auctioneer for example appears to be a constructive abstraction and that instability should be accommodated within theory rather than circumscribed laboratory applications of ge theory focused on issues beyond stability and dynamics are also briefly surveyed

consistency and heterogeneity of individual behavior under uncertainty by using graphical representations of simple portfolio choice problems we generate a very rich dataset to study behavior under uncertainty at the level of the individual subject we test the data for consistency with the maximization hypothesis and we estimate preferences using a two parameter utility function based on faruk gul 1991 this specification provides a good interpretation of the data at the individual level and can account for the highly heterogeneous behaviors observed in the laboratory the parameter estimates jointly describe attitudes toward risk and allow us to characterize the distribution of risk preferences in the population

multiple product firms a nested logit approach this paper proves the existence of a symmetric equilibrium with multiproduct firms using a nested logit model of demand the demand model is parameterized by two variables that characterize different dimensions of preference for variety these reflect intragroup heterogeneity and intergroup heterogeneity a group or nest being the set of products produced by a firm there are then two dimensions to market performance the total number of firms and the range of products produced per firm it is shown that the market equilibrium involves an excessive number of firms but each firm provides too few products copyright 1992 by blackwell publishing ltd

the d level nested logit model assortment and price optimization problems we consider assortment and price optimization problems under the d level nested logit model in the assortment optimization problem the goal is to find the revenue maximizing assortment of products to offer when the prices of the products are fixed using a novel formulation of the d level nested logit model as a tree of depth d we provide an efficient algorithm to find the optimal assortment for a d level nested logit model with n products the algorithm runs in o d n log n time in the price optimization problem the goal is to find the revenue maximizing prices for the products when the assortment of offered products is fixed although the expected revenue is not concave in the product prices we develop an iterative algorithm that generates a sequence of prices converging to a stationary point numerical experiments show that our method converges faster than gradient based methods by many orders of magnitude in addition to providing solutions for the assortment and price optimization problems