information acquisition and under diversification if an investor wants to form a portfolio of risky assets and can exert effort to collect information on the future value of these assets before he invests which assets should he learn about the best assets to acquire information about are ones the investor expects to hold but the assets the investor holds depend on the information he observes we build a framework to solve jointly for investment and information choices with general preferences and information cost functions although the optimal research strategies depend on preferences and costs the main result is that the investor who can first collect information systematically deviates from holding a diversified portfolio information acquisition can rationalize investing in a diversified fund and a concentrated set of assets an allocation often observed but usually deemed anomalous copyright wiley blackwell

consumer demand for food diversity evidence for germany abstract whereas a large number of empirical studies have been devoted to analysing consumer demand for specific products much less attention has been paid to the household s demand for product variety the number of different products consumed in a specific time period this paper analyses consumer demand for food variety in germany the econometric analysis of 4632 households suggests that variety significantly increases with income and the number of children aged between 7 and 17 years and is significantly higher if the family lives in larger cities in east germany and the housekeeping person is not additionally working full time a single male household consumes a significantly smaller number of different food products the significant and positive impact of household income on food variety is in line with the hypothesis that consumption evolves along a hierarchical order as income increases

macroeconomics with endogenous markups and optimal taxation i augment a flexible price dynamic general equilibrium model with any symmetric intratemporal preferences over a variety of goods supplied under monopolistic bertrand or cournot competition to derive implications for business cycle and market inefficiencies endogenous markups can magnify the impact of shocks on consumption and labor supply through intertemporal substitution mechanisms and the optimal fiscal policy requires a variable labor income subsidy and a capital income tax that converges to zero in the long run with an endogenous number of goods and strategic interactions entry also affects markups and the optimal fiscal policy requires also a tax on profits i characterize equilibrium and efficient market structures and derive optimal tax rules for a variety of preferences including a new type of general additive preferences that nest direct indirect implicit and homothetic additivity

the consumption real exchange rate anomaly with extensive margins abstract this paper investigates a consumption real exchange rate anomaly from the open macroeconomics literature known as the backus smith puzzle we both analytically and quantitatively examine how an expansion of trade along extensive margins can contribute to the puzzle s resolution our argument is based on 1 a wealth effect due to changes in the number of product varieties 2 statistical inefficiency in measuring the number of product varieties and 3 market incompleteness contrary to complete asset markets which in general feature overly strong risk sharing properties changes in the number of product varieties under incomplete markets may produce a wealth effect under high trade elasticity since statistical agencies systematically fail to capture the welfare impact arising from that changes data consistent terms of trade and real exchange rates tend to appreciate due to this positive wealth effect this provides a realistic correlation between data consistent real exchange rates and consumption

welfare analysis of uniform entry tax in a general equilibrium model with heterogeneous industries abstract this paper examines whether uniform entry taxes across all industries can improve welfare in a monopolistic competition model with multiple groups of differentiated goods which vary in parameters including their elasticity of substitution and taste for variety the results show that even if taste for variety is high and monopoly power is weak in some industries the uniform tax rate on entries across all industries can improve welfare when the weighted average of taste for variety over all industries is low and when the weighted average of the lerner index of monopoly power over all industries is high

market distortions and local indeterminacy a general approach we provide a methodology to study the role of market distortions on the emergence of indeterminacy and bifurcations it consists in introducing general specifications for the elasticities of the crucial functions defining the aggregate equilibrium dynamics of the model this allows us to study how market distortions influence the range of values for the elasticity of input substitution under which local indeterminacy and bifurcations occur highlighting the main channels and classes of distortions responsible for indeterminacy most of the specific market imperfections considered in the related literature are particular cases of our framework comparing them we obtain several equivalence results in terms of local dynamic properties applying this methodology to the woodford 30 framework we find that distortions in the capital market per se do not play a major role we further show that for empirically plausible values of elasticity of substitution between inputs indeterminacy requires a minimal degree of distortions this degree seems to be high under output market distortions while with labor market distortions the required degree is empirically plausible

when does elastic labor supply cause an inverted u effect of patents on innovation this study analyzes how patent protection affects innovation in an r d based growth model with elastic labor supply we find that increasing patent breadth may generate an inverted u effect on innovation depending on whether the model features the knowledge driven or lab equipment innovation process this result highlights an important interaction between elastic labor supply and the innovation process through which patent protection has an inverted u effect as documented in recent empirical studies

simple market equilibria with rationally inattentive consumers we study a market with rationally inattentive consumers who are unsure of the terms of the offers made by firms but can acquire information about the terms at a cost in a symmetric equilibrium the price set by firms is continuously increasing in the cost of information for consumers and decreasing in the number of firms operating in addition favorable a priori information about a firm leads it to set a higher price and a new entrant can increase demand for incumbents when consumers have heterogeneous costs of information firms selling low quality products may choose to set the highest prices

the refoundation of the symmetric equilibrium in schumpeterian growth models abstract we provide a refoundation of the symmetric growth equilibrium characterizing the research sector of vertical r d driven growth models we argue that the usual assumptions made in this class of models leave the agents indifferent as to where targeting research hence the problem of the allocation of r d investment across sectors is indeterminate by introducing an contamination of confidence in the expected distribution of r d investment we prove that the symmetric structure of r d investment is the unique rational expectations equilibrium compatible with ambiguity averse agents adopting a maxmin strategy

the extensive margin and monetary policy abstract the creation of new firms referred to as the extensive margin is a significant but overlooked dimension of monetary policy a monetary var documents that monetary policy has significant effects on firm creation an analytically tractable model combining sticky prices and firm entry shows that entry alters the transmission of monetary policy innovations acting much like a type of investment in more standard models monetary policy rules that offset the uncertainty of productivity shocks can raise the mean level of entry and thereby welfare suggesting a new motivation for stabilization policy

discrete actions in information constrained decision problems individuals are constantly processing external information and translating it into actions this draws on limited resources of attention and requires economizing on attention devoted to signals related to economic behaviour a natural measure of such costs is based on shannon s channel capacity modelling economic agents as constrained by shannon capacity as they process freely available information turns out to imply that discretely distributed actions and thus actions that persist across repetitions of the same decision problem are very likely to emerge in settings that without information costs would imply continuously distributed behaviour we show how these results apply to the behaviour of an investor choosing portfolio allocations as well as to some mathematically simpler tracking problems that illustrate the mechanism trying to use costs of adjustment to explain stickiness of actions when interpreting the behaviour in our economic examples would lead to mistaken conclusions

taste for diversity and the optimality of economic growth abstract we disentangle the taste for diversity in consumption present in endogenous growth models with expanding product variety from the elasticity of substitution between consumption goods this seriously affects the welfare analysis of the model if taste for diversity is relatively small the market rate of growth may be suboptimally large

aggregation in a model of price competition abstract in a model of price competition single product firms compete for consumers consumers purchase a variable quantity of one of the differentiated goods the paper provides results on equilibrium existence when consumers are heterogeneous in their evaluation of the differentiated goods among each other their evaluation of the differentiated goods relative to the outside good and heterogeneous in income furthermore i provide sufficient conditions for dominance solvability and monotone comparative statics journal of economic literature classification numbers d43 d11

the intrinsic limits of modern economic theory the emperor has no clothes assumptions of the uniqueness and stability of general equilibrium in a walrasian framework have no theoretical justification this paper argues that the key reason for this is that the walrasian model treats people as acting independently of one another especially in their demand behavior this independence plays an essential role in constructing economies with arbitrary excess demand functions thus making individual behavior dependent or similar may open the way to obtaining meaningful restrictions on aggregate excess demand functions copyright 1989 by royal economic society

man bites dog business cycles the newsworthiness of an event is partly determined by how unusual it is and this paper investigates the business cycle implications of this fact signals that are more likely to be observed after unusual events may increase both uncertainty and disagreement among agents in a simple business cycle model such signals can explain why we observe i occasional large changes in macro economic aggregate variables without a correspondingly large change in underlying fundamentals ii persistent periods of high macroeconomic volatility and iii a positive correlation between absolute changes in macro variables and the cross sectional dispersion of survey expectations

industry equilibrium with outside financing and moral hazard implications for market integration abstract in this paper we study industry equilibrium under the assumptions that 1 firms need outside financing and 2 they have a moral hazard problem in taking potentially excessive risks we characterize an industry equilibrium with credit rationing where firms choose not to take risks and compare this to the industry equilibrium in the absence of credit rationing in both cases we show that competition increases and prices decline as markets integrate however in markets with credit rationing there is typically more exit a smaller decline in prices and most strikingly the market value of the industry increases rather than decreases

optimality of debt under flexible information acquisition we study the optimality of debt through the interaction between se curity design and information acquisition an impatient seller designs an asset backed security and a buyer decides whether to buy it to provide liquidity facing dierent securities the buyer has incentives to acquire in formation from dierent aspects of the fundamental which in turn aects security design speci cally the buyer bene ts from information acqui sition at the expense of the seller through adverse selection the seller hence deliberately designs the security to induce the buyer to acquire the information least harmful to the seller s interest since securities can be designed in arbitrary ways the resulting incentive to acquire information is very exible thus we introduce exible information acquisition to capture this interaction we show that debt is uniquely optimal com pared with the security design literature we neither assume monotonicity of the feasible securities nor impose various distributional assumptions on the fundamental or information structures fixed aggregate cash ow and homogeneous information cost are two key factors driving the results jel d86 d82 g32

the welfare cost of one size fits all patent protection to analyze the welfare gain from allowing for differentiated patent protection across sectors this study develops a two sector quality ladder growth model in which patent breadth is a policy variable and derives optimal patent breadth under two patent regimes we show that a uniform optimal patent breadth is a weighted average of sector specific optimal patent breadth and b sector specific optimal patent breadth is larger in the sector that has a larger market size and more technological opportunities to derive the optimal policy we allow for an arbitrary path of patent breadth and derive the optimal path by solving a stackelberg differential game we find that the optimal path of patent breadth under each patent regime is stationary time consistent and subgame perfect finally we perform a numerical investigation and find that even a moderate degree of asymmetry across sectors can generate a significant welfare cost of uniform patent protection

welfare ranking ad valorem and specific tariffs under monopolistic competition actual trade and tariff policy prefers ad valorem tariffs to specific tariffs yet in this paper we show that in a setting of monopolistic competition realizing a given restriction on imports via a specific tariff would generate more consumer utility than obtaining the same restriction via an ad valorem tariff jel classification f12 un classement en terme de bien etre des droits de douane ad valorem et specifiques quand on est en regime de concurrence monopolistique les politiques commerciales en vigueur pref rent les droits de douane ad valorem aux droits de douane specifiques or ce memoire montre que dans un contexte de concurrence monopolistique reduire les importations par le truchement d un droit de douane specifique genere plus d utilite pour le consommateur que les memes restrictions obtenues par le truchement d un droit de douane ad valorem

firm entry markups and the monetary transmission mechanism abstract two business cycle models with endogenous firm and product entry are estimated by matching impulse responses to a monetary policy shock the competition effect implies that entry lowers desired markups and dampens inflation under translog preferences where the substitutability between goods depends on their number we find evidence of such an effect that model generates more countercyclical markups than dixit and stiglitz 1977 monopolistic competition model where price stickiness is the only source of markup fluctuations in contrast a model with strategic interactions between oligopolistic firms cannot generate an empirically relevant competition effect and is statistically equivalent to the dixit stiglitz model

rational inattention in uncertain business cycles the paper proposes endogenous information choice as a channel through which uncertainty affects price dynamics i consider a rational inattention model with volatility uncertainty and endogenous information processing capability according to the model firms learning and optimal attention exhibits inertia and asymmetry in response to volatility changes firms choose to process more information when uncertainty rises especially about aggregate conditions and their pricing behavior changes accordingly using a markov switching factor augmented vector autoregression ms favar the paper also documents a significant positive correlation between volatility and firms responsiveness to macro and microlevel shocks consistent with model predictions

taste for variety and optimum production patterns in monopolistic competition abstract many positive and normative results in models using the monopolistic competition framework of the dixit stiglitz spence type depend on the value of an important parameter the taste for variety in these models however the taste for variety is linked in a close but arbitrary manner to the degree of market power of monopolistic competitors in this paper we make a simple modification to the basic model which clearly disentangles taste for variety and market power we then show how this changes the usual comparisons between social optimum and market outcomes

behavioral heterogeneity and the income effect inspired by the recent literature on aggregation theory this paper introduces hits a semiparametric model of consumer demand that allows for diversity in tastes the strong variation of budget shares observed across income groups has two possible origins the individual income effect and taste differences between poor and rich households consumer surveys reporting repeated cross sections do not permit the direct measurement of these two effects in hits linear heterogeneity allows the gmm estimation of structural coefficients on an aggregate series the joint density of spending and tastes is then recovered from cross sections by a nonparametric procedure involving a deconvolution we estimate the model on british data 1968 1998 and report that taste heterogeneity explains a large fraction of the variation of budget shares with income

implications of rational inattention abstract a constraint that actions can depend on observations only through a communication channel with finite shannon capacity is shown to be able to play a role very similar to that of a signal extraction problem or an adjustment cost in standard control problems the resulting theory looks enough like familiar dynamic rational expectations theories to suggest that it might be useful and practical while the implications for policy are different enough to be interesting

full scale real tests of consumer behavior using experimental data abstract this paper reports on the results of three experiments based on the neoclassical theory of consumer behavior all these experiments were carried out with the aim of simulating real world behavior nonparametric tests applying the theory of revealed preference show that a significant number of individuals exhibit inconsistent behavior if nearly optimizing behavior is postulated then most of these inconsistencies disappear but random choices produce almost the same results the hypothesis of a representative consumer statistical average behavior seems a more fruitful approach

labor market dynamics when un employment is a social norm this paper proposes a new keynesian model with search and matching frictions in the labor market that can account for the cyclicality and persistence of vacancies unemployment job creation inflation and the real wage after a monetary shock motivated by evidence from psychology unemployment is modeled as a social norm the norm is defined here as the belief that individuals in society prioritize or should prioritize the search for gainful employment whereas those who do not are perceived as outside the norm and consequently stigmatized households pressure the unemployed to find jobs the fewer unemployed workers there are the more supporters the norm has and therefore the greater the pressure and psychological cost experienced by each jobseeker as this psychological cost is procyclical it hinders the wage from absorbing most of the effect of the shock thus the model is able to capture the high volatility of vacancies and unemployment observed in the data accounting for the shimer puzzle the paper also departs from the literature by introducing price rigidity in the labor market inducing additional inertia and persistence in inflation and the real wage after a monetary shock the model s responses after a monetary shock are in line with the responses obtained from a var on us data

tariffs in monopolistic competition models with leisure consumption trade off abstract this note introduces a leisure consumption trade off into monopolistic competition models resulting in ambiguous welfare effects of tariff protection a small tariff is welfare reducing when the terms of trade effect is smaller than an international returns to scale effect

transformations of the commodity space behavioral heterogeneity and the aggregation problem aggregation in exchange markets is studied by imposing restrictions on distributions of the households characteristics approximate bounds for market demand price elasticities that depend upon specific measures of behavioral heterogeneity are provided increasing behavioral heterogeneity makes aggregate expenditures more independent of prices this has strong consequences for the prevalence in the aggregate of the weak axiom of revealed preference of gross substitutability and on uniqueness and stability of the walrasian exchange equilibrium these strong macroeconomic regularities are obtained essentially through distributional assumptions as no rationality requirements are imposed on individual demand functions other than homogeneity and walras law journal of economic literature classification numbers d11 d41 d50 el 1992 academic press lnc there are still quite a few unpleasant gaps nowadays between macroanalysis and microanalysis of socioeconomic systems a leading instance drawn from social choice theory is arrow s celebrated impossibility theorem 1 which states that any attempt to aggregate individual preferences into a consistent social ordering or a collective choice procedure satisfying a few appealing requirements is bound to fail the impossibility arises however only if one insists that the procedure should work for every possible environment or in other words for all distributions of individual preferences a possible resolution of the problem is therefore to identify broad classes of distributions of preferences for which aggrega the bulk of the research reported in this paper was essentially done at yale university during the fall semester of 1990 i thank all my colleagues for their support and comments especially martin shubik herbert scarf and truman bewley i also had very useful conversations with jorgen weibull mike jerison andreu mas colell christian gouri6roux camille bronsard guy laroque bruno jullien and bernard caillaud i am much indebted to ai klevorick for his comments on an earlier draft but my greatest debt is to werner hildenbrand whose pioneering insights and stubborn insistance have over the years kept quite a few of us struggling beyond the fads of the moment with the aggregation problem our profession is fortunate indeed to have him around

portfolio choice attention allocation and price comovement abstract this paper models the attention allocation of portfolio investors investors choose the composition of their information subject to an information flow constraint given their expected investment strategy in the next period which is to hold a diversified portfolio in equilibrium investors choose to observe one linear combination of asset payoffs as a private signal when investors use this private signal to update information about two assets changes in one asset affect both asset prices and may lead to asset price comovement the model also has implications for the transmission of volatility shocks between two assets

the effect of a common currency on the volatility of the extensive margin of trade abstract this paper studies the effects of the european monetary unification on the volatility of the extensive margin of trade first we highlight empirical novel facts about the effects of monetary unification we build country level measures of the extensive margin of intra emu exports and describe how their volatilities evolved over time we show that the adoption of a common currency has been associated with an increase of the volatility of the extensive margin of exports for most countries and a decrease in the volatility of the extensive margin of exports for germany second we address this question theoretically and build a two country version of the model of ghironi and melitz 2005 with endogenous entry heterogenous firms endogenous tradability endogenous labor supply and sticky prices we compare the volatility of the extensive margin of trade under fixed exchange rates and in a monetary union monetary unification does imply an increase in the volatility of the extensive margin of trade for pre emu followers such as france or the netherlands and a decrease in the volatility of the extensive margin of trade for the leader germany this pattern is qualitatively consistent with the data but arises only if monetary policy responds moderately to output

a quantized approach to rational inattention abstract in this paper i propose a model of rational inattention where the choice variable is a deterministic function of the exogenous variables and still only a finite amount of information is being used this holds provided the choice variable is discrete rather than continuous that is the mapping from the realization of the exogenous variables to the endogenous ones is piece wise constant thus limited information is now a source of lumpiness in behavior rather than a source of noise the approach is applied to a simple static model of price setting where individual price setters face aggregate monetary shocks and idiosyncratic productivity shocks the effect of aggregate money shocks on output and prices is studied it is shown that as the variance of idiosyncratic shocks become large the aggregate log price level converges to a linear function of the aggregate money shock with a coefficient which is strictly between 0 and 1 consequently unanticipated aggregate money shocks have real effects on output in contrast to the sticky price model of caplin and spulber 1987 but these effects are smaller than in standard rational inattention models or in the lucas 1972 misperception model

strategic procurement openness and market structure abstract we examine strategic procurement behaviour by governments and its effect on market structure in sectors such as defence and pharmaceuticals where the government is the dominant consumer in a world economy with trade between producer countries and between producers and non producers we use a modified dixit stiglitz utility function with an independent taste for variety there is free entry and exit by firms but by anticipating their participation constraint governments can indirectly choose the number of domestic firms and their size through its choice of procurement price unlike the standard model with no independent taste for variety and no external sector of non producer countries there are incentives for subsidies openness impacts on industrial structure and procurement coordination between producer countries affects firm numbers

on monopolistic competition and optimal product diversity workers rents also matter in the dixit stiglitz model of monopolistic competition entry of firms is socially too small other authors have shown that excess entry is also a possibility with other preferences for diversity we sow that workers rents also contribute to explain excess entry through a general equilibrium mechanism larger wages indeed raises the aggregate earnings and firms sales and profits which entices too many firms to enter we discuss the possibility of over provision of varieties by comparing the equilibrium to unconstrained and constrained social optima and to other regulatory frameworks where wages are not controlled

the implications of additive community preferences in a multi consumer economy we investigate the consequences of imposing additivity on community preferences we show that there are important implications of additive community preferences that are not implied by the additivity of a single consumer s preferences in particular we show that imposing additivity on community preferences implies the existence of a representative consumer with a utility function in the ces family we demonstrate the restrictive nature of these implications with three examples our interpretation of the results is that single consumer models are unable to adequately represent important features of multi consumer economies

strategic pricing with rational inattention to quality this paper studies both theoretically and experimentally the pricing strategy of a rm that faces a consumer who is rationally inattentive to product quality sims 2003 in a standard sequential pricing game rational inattention to quality produces two types of mixed strategy perfect bayesian equilibria one where sellers pool at a low price and buyers are fully inattentive to quality and one where there is semi pooling at a high price and buyers are selectively attentive to quality i characterize these

market structure cost asymmetries and fiscal policy effectiveness abstract imperfectly competitive macroeconomic models typically assume a symmetric equilibrium with identical firms despite the fact that most industries are characterised by substantial degrees of firm heterogeneity we examine how inter firm efficiency gaps affect fiscal policy effectiveness under monopolistic competition

price points and price dynamics abstract a standard model of price setting is extended to include an important role for price points as well as sticky information it makes empirically reasonable predictions about the frequency of price adjustments the sizes of price increases and decreases the shape of the hazard function the fraction of price changes that are price increases and the relationship between price changes and inflation when the model of price setting is integrated into a small scale dsge model it implies plausible aggregate effects of monetary policy in contrast to a model with a prominent role for price points but no information rigidities

fiscal policy monopolistic competition and finite lives abstract this paper studies the short run transitional and long run output effects of permanent and temporary shocks in public consumption under various financing methods to this end a dynamic macroeconomic model for a closed economy is developed which features a perfectly competitive final goods sector and a monopolistically competitive intermediate goods sector finitely lived households consume final goods supply labor and save part of their income amongst the findings for a permanent rise in public consumption are i monopolistic competition increases the absolute value of the balanced budget output multiplier ii positive long run output multipliers are obtained only if the generational turnover effect is dominated by the intertemporal labor supply effect iii short run output multipliers under lump sum tax financing are smaller than long run output multipliers if labor supply is elastic and iv bond financing reduces the size of long run output multipliers as compared to lump sum tax financing and may give rise to non monotonic adjustment paths if labor supply is sufficiently elastic and the speed of adjustment of lump sum taxes is not too high temporary bond financed fiscal shocks are shown to yield i permanent effects on output and ii negative long run output multipliers

is there always too little research in endogenous growth with expanding product variety abstract it is generally believed that models of endogenous growth with expanding product variety typically yield a too low level of research we show here that this result is due to the implicit choice of a particular value for a crucial parameter once this parameter is set free one finds that too much research can occur as well

the microfoundations project in general equilibrium theory the author 1 argues that the long lived microfoundations project based on general equilibrium models has come to an end and 2 shows that non walrasian models intended to provide microfoundations for macroeconomics are inadequate the arguments are derived from the sonnenschein mantel debreu smd demonstration of the arbitrariness of aggregate excess demands in general equilibrium models of the walrasian arrow debreu mckenzie type the issues raised have significance for the proper method of modeling macroeconomic phenomena for instance the smd results have led a growing number of general equilibrium theorists to make assumptions concerning macroeconomic structure in order to analyze other regularities at the macro level these points validate the position that systematic macroeconomic phenomena are intrinsically macroeconomic copyright 1994 by oxford university press

the dynamic effects of currency union on trade abstract the response of trade to a monetary union is a dynamic process an empirical study of the european monetary union finds that the extensive margin of trade in new goods responded several years ahead of emu implementation and ahead of overall trade volume a dynamic rational expectations trade model shows that early entry of new firms in anticipation is explainable as a rational forward looking response to news the model helps identify which types of trading frictions are reduced by a currency union and shows how new entry can be affected by uncertainty about emu

the struggle to survive in the r d sector implications for innovation and growth by allowing for investment activities by research and development r d firms to prevent product obsolescence we show that if legal patent protection is too strong a higher r d subsidy rate delivers insufficient investments for survival in the r d sector depressing innovation and growth in the long run

optimal monetary policy with endogenous entry and product variety deviations from long run price stability are optimal in the presence of endogenous entry and product variety in a sticky price model in which price stability would be optimal otherwise long run inflation deflation is optimal when the benefit of variety to consumers falls short of exceeds the market incentive for creating that variety the desired markup price indexation exacerbates this mechanism plausible preference specifications and parameter values justify positive long run inflation rates however short run price stability around this non zero trend is close to optimal even in the presence of endogenously time varying desired markups that distort the intertemporal allocation of resources

patents r d subsidies and endogenous market structure in a schumpeterian economy this study explores the different implications of patent breadth and r d subsidies on economic growth and endogenous market structure in a schumpeterian growth model we find that when the number of firms is fixed in the short run patent breadth and r d subsidies serve to increase economic growth as in previous studies however when market structure adjusts endogenously in the long run r d subsidies increase economic growth but decrease the number of firms whereas patent breadth expands the number of firms but reduces economic growth therefore in accordance with empirical evidence r d subsidy is perhaps a more suitable policy instrument than patent breadth for the purpose of stimulating long run economic growth

the ramsey model with monopolistic competition and general preferences abstract i extend the ramsey model of consumption and growth to general preferences over a variety of goods supplied under monopolistic competition and derive the implications for markup variability and macroeconomic dynamics the model delivers a modified euler equation that affects the short run dynamics of consumption when the relative risk aversion is decreasing monopolistic competition generates countercyclical markups and compared to perfect competition magnifies the impact of shocks on consumption through new intertemporal substitution mechanisms

investigating nonneutrality in a state dependent pricing model with firm level productivity shocks in a model with fixed cost of price adjustment and idiosyncratic shocks two parameterizations match a large set of microeconomic facts yet display different degrees of nonneutrality although there is substantial nonneutrality in both cases the model does not behave like a time dependent model as changes in the distribution of firms account for roughly a third of the short run response of the price level to a monetary shock we use the model to examine how aggregating firm behavior can generate flat hazards we also find that a recently developed steady state statistic is an imperfect guide to characterizing nonneutrality

on time inconsistency a technical issue in stackelberg differential games abstract stackelberg differential games are useful settings in which optimal government policies can be studied this paper argues that the analysis of these games involves a key technical issue in particular we question the necessity for optimality of one boundary condition invoked in existing literature the issue is of key interest because the boundary condition is largely responsible for the time inconsistency results previously obtained we show that the boundary condition is not necessary in some cases as a result our finding undermines the credibility of the existing conclusions journal of economic literature classification numbers c61 e62 h21

rigid pricing and rationally inattentive consumer abstract this paper proposes a mechanism leading to rigid pricing as an optimal strategy it applies a framework of rational inattention to study the pricing strategies of a monopolistic seller facing a consumer with limited information capacity the consumer needs to process information about the realized price while the seller is perfectly attentive the seller chooses to price rigidly i e prices respond to changes in the unit input cost less than if the consumer was perfectly attentive the rigidity is sometimes manifested by discreteness of prices the seller charges a finite set of different prices even for a continuous range of unit input costs the seller does so to provide the consumer with easily observable prices which stimulates her to consume more and increases the seller s profit

what determines aggregate returns to scale abstract this paper develops a unified framework that incorporates four features important in existing models with increasing returns fixed costs decreasing marginal costs product variety and market power when fixed costs are not allowed to vary and profits are imposed to be zero in every period only the degree of returns to variety determines the degree of aggregate increasing returns to scale when fixed costs respond to changes in aggregate activity or the zero profit condition does not hold in the short run aggregate returns depend not only on product variety but also on diminishing marginal costs or market power the degree of market power however does not affect input prices which are critical to determine the uniqueness of equilibrium

demand for differentiated products discrete choice models and the characteristics approach we propose a specific characteristics framework in order to construct linkages between alternative conceptual approaches to modelling product differentiation first it is shown that a demand system which satisfies the gross substitutes property imposes specific requirements on the locations of products in particular the dimension of the characteristics space must be larger than or equal to the number of products minus one we then identify a method for casting a given demand system subject to certain restrictions into our characteristics framework this is illustrated for the logit probit and linear probability models of discrete choice theory finally we find a characteristics representation of the ces representative consumer

international protection of intellectual property we study the incentives that governments have to protect intellectual property in a trading world economy we consider a world economy with ongoing innovation in two countries that differ in market size and in their capacities for innovation after describing the determination of national patent policies in a non cooperative regime of patent protection we ask why is intellectual property better protected in the north than in the south we also study international patent agreements by deriving the properties of an efficient global regime of patent protection and asking whether harmonization of patent policies is necessary or sufficient for global efficiency jel o34 f13 during the 1980 s and early 1990 s the united states and several european countries expressed strong dissatisfaction with what they deemed to be inadequate protection of intellectual property in many developing countries the developed countries made the upgrading of intellectual property rights iprs one of their highest priorities for the uruguay round of trade talks their efforts bore fruit in the agreement on traderelated aspects of intellectual property rights trips which was approved as part of the final act of the uruguay round trips establishes minimum standards of protection for several categories of intellectual property for example in the area of new technology it essentially harmonizes

heuristic thinking and limited attention in the car market can heuristic information processing affect important product markets analyzing over 22 million wholesale used car transactions we find evidence of left digit bias in the processing of odometer values whereby individuals focus on the number s leftmost digits the bias leads to discontinuous drops in sale prices at 10 000 mile odometer thresholds along with smaller drops at 1 000 mile thresholds these findings reveal that information processing heuristics matter even in markets with large stakes and easily observed information we model left digit bias in an inattention framework and structurally estimate the inattention parameter empirical patterns suggest the results are driven by final customers rather than professional agents jel d12 d44 d83 l81

logit ces and rational inattention abstract we study the fundamental links between two popular approaches to consumer choice the multinomial logit model of individual discrete choice and the ces utility function which describes a diversified choice of a representative consumer we base our analysis on the rational inattention ri model and show that the demand system of ri agents each of which chooses a single option coincides with the demand system of a fictitious representative agent with ces utility function thus the diversified choice of the representative agent may be explained by the heterogeneity in signals received by the ri agents we obtain a new interpretation for the elasticity of substitution and the weighting coefficients of the ces utility function specifically we provide a correspondence between parameters of the ces utility function prior knowledge and marginal cost of information

heterogeneity biases distributional effects and aggregate consumption an empirical analysis using stratified microdata using stratified microdata from the canadian famex 78 86 surveys this paper investigates whether observed heterogeneity in marginal propensities to consume across strata actually hinders the aggregation process despite significant heterogeneity in marginal responses the divergences between aggregate predicted consumption and the predictions from a model that uses average strata responses are found to be small whenever the strata demands are approximatively linear at the mean and the commodity group considered is not a luxury good on the other hand some cross sectional estimates obtained by pooling the strata are shown to be contaminated by unwanted cross moments further the analysis reconciles the fact that while there exists significant heterogeneity in consumer demands the related distributional effects in the aggregate equation have not been found to be important

optimal sticky prices under rational inattention this paper presents a model in which price setting firms decide what to pay attention to subject to a constraint on information flow when idiosyncratic conditions are more variable or more important than aggregate conditions firms pay more attention to idiosyncratic conditions than to aggregate conditions when we calibrate the model to match the large average absolute size of price changes observed in micro data prices react fast and by large amounts to idiosyncratic shocks but only slowly and by small amounts to nominal shocks nominal shocks have strong and persistent real effects we use the model to investigate how the optimal allocation of attention and the dynamics of prices depend on the firms environment jel e 3 e5 d8

efficiency gaps love of variety and international trade we develop a general equilibrium monopolistic competition model of trade with technical heterogeneity among firms and countries with free entry technical asymmetries between firms result in the endogenous determination of the equilibrium average efficiency of the industry we show that trade reduces increases the minimum efficiency required to survive in the more less efficient country this has important welfare implications 1 contrary to the constant elasticity of substitution homogeneous firms model trade affects welfare even when there is no love of variety 2 there are circumstances in which trade liberalization leads to a loss of consumer welfare

globalization and specialization abstract the popular dixit stiglitz ethier framework proposes that globalization increases the menu of intermediate goods available to downstream firms and that gains from specialization raise welfare unambiguously this study shows that both results depend critically on the assumption that demand elasticities are invariable the more general framework presented here provides two main insights first whether specialization rises or falls depends ultimately on the shape of the cost function and second globalization can actually reduce welfare in the case when specialization falls

optimal taxation with imperfect competition and aggregate returns to specialization in this paper we explore the proposition that in economies with imperfect competitive markets the optimal capital income tax is negative and the optimal tax on firms profits is confiscatory we show that if the total factor productivity as well as the measure of firms or varieties are endogenous instead of fixed then the optimal fiscal policy can lead to different results the government faces a trade off between the fixed costs that the society pays for the

allocational efficiency with heterogeneous firms disentangling love of variety and market power we analyze allocational efficiency and first best industrial policy in monopolistic competition when love of variety is disentangled from market power and firms are heterogeneous