optimum product diversity and the incentives for entry in natural oligopolies this paper concerns the classification of biases in the set of produced varieties in a monopolistically competitive equilibrium in the natural oligopoly setting that is we analyze the relationship between the set of produced goods in equilibrium when fixed costs are small and the set of produced goods by a social planner when fixed costs equal zero it is shown that if all of the goods are substitutes there are never too few varieties and there may be too many conversely if the goods are all complementary there are never too many and there may be too few

cost reduction competition and industry performance in many markets firms compete over time by expending resources with the purpose of reducing their costs sometimes the cost reducing investments operate directly on costs in many instances they take the form of developing new products that deliver what customers need more cheaply therefore product development can have the same ultimate effect as direct cost reduction in fact if one thinks of the product as the services it delivers to the customer in the way that lancaster pioneered then product development often is just cost reduction

integrated regressors and tests of the permanent income hypothesis abstract we use recent research on estimation and testing in the presence of unit roots to argue that hall s 1978 t and f tests of whether consumption is predicted by lagged income or by lags of consumption beyond the first are asymptotically valid a monte carlo experiment suggests that the asymptotic t and f distributions provide a good approximation to the actual finite sample distribution

monopolistic competition in the spirit of chamberlin a general model this paper develops a model of large group chamberlinian monopolistic competition in which 1 there are many firms producing differentiated commodities 2 each firm is negligible in that it can ignore its impact on and hence reactions from other firms 3 free entry leads to zero profit of operating firms but 4 each firm faces a downward sloping demand curve the existence of a monopolistically competitive equilibrium is established in a companion paper more particular questions such as whether the market provides too many or too few products are addressed for a special case of the model

product variety informative advertising and price competition abstract in many product categories consumer tastes are diverse and firms use finely targeted advertising to inform consumers about their products this article proposes a model of informative advertising that allows for diverse consumer tastes and multiple competing firms using this framework the authors analyze how diversity in consumers tastes informative advertising and improvements in advertising technology may influence prices first informative advertising can lead to lower prices if consumer valuations are high however if consumer valuations are low informative advertising can lead to higher prices second when consumer valuations are high price increases with greater diversity in tastes though this result reverses if consumer valuations are low third improvements in advertising technology lead to higher levels of advertising when consumer valuation is high but the opposite effect can occur when consumer valuation is low the authors relate these theoretical findings to previous e

second best subsidies in monopolistic competition abstract in the spence dixit stiglitz model of monopolistic competition an output or input subsidy is welfare improving under competitive conjecture the significance of this result is that it holds even when the subsidy exacerbates the potential problem of excess product diversity

do consumers search for the highest price oligopoly equilibrium and monopoly optimum in differentiated products markets we develop a model of search among substitutes for the best combination of commodity variant and price in which the structure of search costs is manipulable by the suppliers of these variants e g by joining an existing market or opening a new one we analyze the subgame perfect equilibria arising in a multistage game involving specialized firms choice of entry variant and price and we compare them to a multiproduct monopolist s optimal choice we show that equilibrium prices increase in the number of substitutes sold in one market and that in the situation considered here monopoly increases welfare

the rationale of the mean standard deviation analysis skewness preference and the demand for money publisher summary this chapter discusses the rationale of the mean standard deviation analysis skewness preference and the demand for money in january 1969 issue of the review of economic studies karl borch and martin feldstein separately criticized the widely used mean variance analysis of portfolio selection borch contended that any system of upward sloping mean standard deviation e s indifference curves can be shown to be inconsistent with the basic axiom of choice under uncertainty he pointed out that one can always pick any two points on an upward sloping indifference curve to represent two bernoulli distributions with probability 1 p of gaining the same amount x in both the cases and probability p of gaining y1 in the case of one distribution and y2 in the case of the second distribution with y2 y1 if the second distribution represents the point to the northeast of the other point then by the dominance axiom the second distribution must be preferred to the first which contradicts the basic meaning of indifference curves feldstein by using a log utility function and a lognormal distribution for investment outcome showed that e s indifference curves for a risk averter need not be convex downwards though upward sloping they would change from convex to concave once the standard deviation of the outcome exceeds the mean multiplied by on the face of it this seems to suggest that risk aversion might decrease as risk is increased beyond a certain extent

production trade and migration with differentiated skilled workers a model is developed in which the output of one traded sector e g high tech is produced using consultants who supply differentiated skilled services an external economy is shown to exist which in turn implies a the suboptimal supply of skilled specialists b multiple equilibria and c disadvantages for small and or late developing economies although the results indicate a positive role for subsidies the model emphasizes the need to subsidize the use not training of skilled specialists the latter policy subsidizes foreigners through emigration production commerce international et migration dans un contexte ou laforce de travail est qualifieze et differenciee l auteur developpe un modele dans lequel la production dans un secteur ofu les biens sont transiges internationalement haute technologie requiert l usage de consultants qui fournissent des services qualifies et differencies on montre l existence d economies externes qui font que a il y a offre sous optimale d experts qualifies b des equilibres multiples existent et c les petites economies ou celles qui se sont developpees tardivement sont desavantagees bien que les resultats indiquent que les subventions peuvent jouer un role positif le modele suggere qu il faut subventionner l utilisation et non pas la formation de specialistes qualifies cette derniere politique subventionne les etrangers via la migration

on the proportionality and homogeneity of consumption and income in its certainty equivalence form consumption is proportional to the sum of human and non human wealth with labour income uncertainty the proportionality takes the form of homogeneity of consumption with respect to the components of wealth in this paper we analyse the stochastic properties of labour income that yield the homogeneity property

the permanent income hypothesis estimation and testing by instrumental variables the permanent income hypothesis with rational expectation is restated estimated and tested by an instrumental variables technique on the postwar u s aggregate time series data the hypothesis is accepted on a consumption series which includes service flows from consumer durables if the consumption series is the one in the national income and product accounts the hypothesis is decisively rejected an explanation is suggested to reconcile the conflicting test results

disagreement and biases in inflation expectations empirical work documents substantial disagreement in inflation expectations obtained from survey data furthermore the extent of such disagreement varies systematically over time in a way that reflects the level and variance of current inflation this paper oers a simple explanation for these facts based on asymmetries in the forecasters costs of over and under predicting inflation our model implies biased forecasts with positive serial correlation in forecast errors and a cross sectional dispersion that rises with the level and the variance of the inflation rate it also implies that forecast errors at dierent horizons can be predicted through the spread between the short and long term variance of inflation we find empirically that these patterns are present in inflation forecasts from the survey of professional forecasters a constant bias component not explained by asymmetric loss and rational expectations is required to explain the shift in the sign of the bias observed for a substantial portion of forecasters around 1982

the role of central bank transparency for guiding private sector forecasts central banks have become remarkably more transparent over the last few decades in this paper we study the effects of this evolution focusing on whether enhanced central bank transparency lowers dispersion among professional forecasters of key economic variables we use a large set of proxies for central bank transparency in 12 advanced economies we find evidence for a sizeable effect e g by announcing a quantified inflation objective or by publishing inflation and output forecasts however there are decreasing marginal effects to increases in transparency and the disagreement among the expectations of the general public is not affected this suggests that there are possible limits to transparency

equilibrium with product differentiation tive consumer formulations is used to examine the properties of single and multiple price equilibria conditions under which decreases in the intensity of consumer preferences reduce price are given it is shown that with certain types of demand curves entry can eliminate price cost markups even given product differentiation if competition is localized it is demonstrated that entry does not affect the markup finally the effect of spurious product differentiation on price is examined

effects of transparency monetary policy signalling and clarity of central bank communication on disagreement about inflation expectations abstractthe literature on transparency and central bank communication and the literature on disagreement about expectations are evolving however both have been evolving separately despite the advances in the literature several key issues remain open and there are gaps to be filled therefore this study analyses the effects of monetary policy signalling and clarity of central bank communication on disagreement about inflation expectations it also investigates whether greater transparency coincides with lower levels of disagreement in inflation expectations in brazil the findings suggest that transparency is important to reduce disagreement about inflation expectations moreover our estimates indicate that central bank communication and clarity affect disagreement about inflation expectations in brazil

economies of scope within market frameworks abstract the purpose of this paper is to look at the circumstances under which a market organised to take advantage of economies of scope is superior to one neglecting these but as a consequence involving less monopoly power the question is investigated theoretically by means of two simple models in order to obtain insights into the main forces involved it transpires that if cross elasticities of demand are low relative to own price elasticities then gaining economies of scope is likely to be worthwhile from society s viewpoint otherwise not

why do forecasters disagree lessons from the term structure of cross sectional dispersion abstract key sources of disagreement among economic forecasters are identified by using data on cross sectional dispersion in forecasters long and short run predictions of macroeconomic variables dispersion among forecasters is highest at long horizons where private information is of limited value and lower at short forecast horizons moreover differences in views persist through time such differences in opinion cannot be explained by differences in information sets our results indicate they stem from heterogeneity in priors or models differences in opinion move countercyclically with heterogeneity being strongest during recessions where forecasters appear to place greater weight on their prior beliefs

central bank communication and monetary policy a survey of theory and evidence over the last two decades communication has become an increasingly important aspect of monetary policy these real world developments have spawned a huge new scholarly literature on central bank communication mostly empirical and almost all of it written in this decade we survey this ever growing literature the evidence suggests that communication can be an important and powerful part of the central bank s toolkit since it has the ability to move financial markets to enhance the predictability of monetary policy decisions and potentially to help achieve central banks macroeconomic objectives however the large variation in communication strategies across central banks suggests that a consensus has yet to emerge on what constitutes an optimal communication strategy

monopolistic competition and preference diversity approach our model is especially attractive because it starts from economic primitives a specification of the set of possible individual preference patterns it shows how specific properties of the distribution of preferences translate into properties of aggregate demand this allows us to understand the relationship between the distribution of preferences and the degree to which the market introduces biases in product selection this paper presents a general model of the demand for differentiated products which has as special cases two of the most popular approaches used to analyse welfare and competition in monopolistically competitive markets the model of spatial competition on the circle and the model of symmetric aggregate demand the circle model is attractive because both demand and costs have a definite and easy to visualize physical foundation and because it is tractable salop 1979 provides an exemplary modem analysis with this model one can analyze the relationship between the optimal amount of product variety and the amount which a monopolistically competitive market will support in many plausible cases competition produces too much variety such a strong conclusion raises questions of robustness almost simultaneously spence 1976 and dixit and stiglitz 1977 developed an alternative approach to monopolistic competition based upon the chamberlinian assumption of symmetry see also shubik 1959 rather than specifying a distribution of preferences and deriving demand through aggregation as did salop and his predecessors these authors started by specifying a symmetric aggregate benefit function indicating how social welfare depends on the amounts of the various products supplied both spence and dixit stiglitz were able to show that the welfare conclusions from the circle model were not robust depending on the functional form of the benefit function equilibrium may entail either excessive or insufficient product variety 1 the assumption of symmetric demand has proven fruitful in the analysis of many economic problems it is therefore natural to ask what distribution of tastes would give

disagreement in inflation expectations empirical evidence for colombia the literature on expectation disagreements in emerging economies is scarce this paper examines the disagreements in inflation expectations for the colombian economy during the 2010 2017 period w

a simple model of optimum life cycle consumption with earnings uncertainty abstract we analyze the optimum consumption path of an individual who maximizes expected discounted utility over an infinite horizon when savings earn a fixed return and uninsured wage earnings follows a two state random process it is shown that optimum consumption always changes discontinuously with the level of earnings this discontinuity is bounded by the difference in earnings across states for the case where the subjective discount rate is equal to the interest rate and the hazard rate nondecreases over time it is shown that if wage earnings are expected to increase decrease then consumption strictly increases decreases over time

equilibrium and optimality in a mean variance model this article reexamines an old debate over the optimality of market allocations in a symmetric mean variance world with production nonconvexities imperfectly correlated outputs and free entry we show that walrasian equilibrium does not exist that non walrasian equilibrium under price taking behavior allocates resources optimally between the risky and risk free sectors but spreads resources in the risky sector over an insufficient number of activities and that non walrasian equilibrium under consistent conjectures allocates insufficient resources to the risky sector and spreads them over an excessive number of activities these results have analogues in the theory of product differentiation

rational conjectures in the theory of oligopoly abstract the paper employs the notion of rational conjectural equilibrium to remove the arbitrary nature of conjectures about rivals reactions which characterises the traditional non cooperative theory of oligopoly a general definition of these equilibria is given and the concept is then applied to a simple duopoly model the standard models of perfect competition monopoly limit price dominant firms are shown to emerge as special cases of rational conjectural equilibria

consistent conjectures in monopolistic competition abstract models of monopolistic competition such as dixit and stiglitz and spence typically assume firms take market variables as parametric this conjectural variation corresponds to chamberlin s large group approximation although these models need not have a large number of firms the present note following perry shows that consistent conjectures about the size and number of rivals can provide a more satisfactory basis for this assumption

product proliferation in characteristics space the uk fertiliser industry in recent years a number of theoretical papers have addressed both the positive and normative aspects of the problem of how competitive products may be located in characteristics space the major theoretical antecedents have been hotelling s analysis of spatial competition 6 chamberlin s analysis of product differentiation 1 2 and lancaster s goods characteristics theory of demand 7 unfortunately there has been little corresponding empirical analysis two approaches in the theoretical analysis seem to have predominated firstly the examination of the welfare implications of product variety offered in equilibrium conditions 2 and secondly the dynamics of product competition using the spatial competition analogy 3 this paper which adopts the second approach uses an adaptation of lancaster s goods characteristics framework it examines the process of product competition in the uk agricultural fertiliser market the first and second sections briefly outline the main features of the goods characteristics and spatial competition theories and the uk fertiliser market respectively the third section contains the empirical analysis

the economics of product variety a survey demand for variety may arise from a taste for diversity in individual consumption and or from diversity in tastes even when each consumer chooses a single variant the full degree of variety potentially demanded will not in general be supplied because scale economies even to a small degree mean that the potential welfare or revenue gain from greater variety must be balanced against the lower unit production costs with fewer variants the economics of product variety consists essentially in analysing the effect of this balance in different situations and comparing the degree of product variety for different market structures with each other and with the optimum the survey commences with the work on market structures with single product firms generalized monopolistic competition tracing modern developments in both the chamberlinian and hotelling traditions the latter has been particularly fruitful due to the expansion of the original locational ideas into virtual spaces in product characteristics the emphasis in recent work on product variety has been on multiproduct firms in both monopolistic and oligopolistic structures including strategic market preemption although most work has been in a full information context there have been advances in product variety under imperfect information either by consumers to properties of the firms products or firms as to consumers demands

the logit model of monopolistic competition brand diversity one of the important issues in the literature on monopolistic competition concerns whether the free entry equilibrium will provide sufficient variety of differentiated brands this paper examines variety issue using the logit choice model to capture brand differentiation the consumption value of each brand is drawn from the extreme value distribution and the consumer then purchases the brand with the highest value with the resulting demand structure the authors find that monopolistic competition results in two few firms and thus too few brands from the viewpoint of consumers this result supports the findings of other models with symmetrically differentiated brands copyright 1990 by blackwell publishing ltd

the existence of equilibrium in discontinuous economic games i theory the article presents information about the existence of equilibrium in discontinuous economic games in this paper and its sequel presents study the existence of nash equilibrium in games where agents payoff functions are discontinuous the enquiry is motivated by a number of recent studies that have uncovered serious existence problems in seemingly innocuous economic games in the sequel to this paper authors have explained the utility function in the economic games referred to earlier are neither continuous nor quasi concave however they demonstrate that the payoff functions in mildly modified versions of these constructs exhibit two weaker forms of continuity which together with the requirement of quasi concavity suffice for the existence of an equilibrium from this one may conclude that at least in the modified versions of these models discontinuities in the payoff functions are not the real source of the problem rather it is the failure of the payoff functions to the quasi concave which is responsible for the non existence of equilibrium these observations bear on the existence of nash equilibrium in pure strategies

optimal central bank transparency should central banks increase their degree of transparency any further we show that there is likely to be an optimal intermediate degree of central bank transparency up to this optimum more transparency is desirable it improves the quality of private sector inflation forecasts but beyond the optimum people might 1 start to attach too much weight to the conditionality of their forecasts and or 2 get confused by the large and increasing amount of information they receive this deteriorates the perceived quality of private sector inflation forecasts as a result inflation is set in a more backward looking manner resulting in higher inflation persistence by using a large scale panel data set on the transparency of central banks we find empirical support for an optimal intermediate degree of transparency at which inflation persistence is minimized our results indicate that while several central banks would benefit from further transparency increases some already have reached the optimal level

value of an additional firm in monopolistic competition the paper develops a model of monopolistic competition in which the satisfaction levels consumers get from products are independently and identically distributed potential substitution among products then generates demand curves through the mechanism of order statistics the value of extra variety can be calculated directly pareto lognormal and beta distributions are investigated using numerical integration some but not all cases support the argument that the optimal number of firms exceeds the equilibrium number

consumption puzzles and precautionary savings abstract when marginal utility is convex agents accumulate savings as a precautionary measure against labor income eventualities this paper shows that precautionary savings can go a long way in making the excess growth excess smoothness and excess sensitivity features of consumption consistent with the stochastic processes of labor income observed in the u s at the microeconomic level

sources of disagreement in inflation forecasts an international empirical investigation abstract central to the conduct of monetary policy are inflation forecasts inflation forecasts are not unique central banks and professional organizations generate inflation forecasts while households are surveyed about their inflation outlook this paper estimates inflation forecast disagreement for nine economies over the 1999 2009 period five of which target inflation i find that central bank transparency tends to increase forecast disagreement to the extent this reflects the attention paid to inflation performance the implication is that transparency is beneficial moreover this finding does not appear to be a feature that applies only to central banks that must adhere to an inflation target

monopolistic competition and a firm s product range abstract a model is presented which assumes that firms maximise profits with respect to both the number of varieties supplied as well as the output level of a typical variety the incentive to produce more than one variety comes from a cost advantage due to inter product economies it is found that in a long run free entry equilibrium the industry is characterised by too few product varieties and each variety is over supplied compared to the welfare maximum for any conjectural variation elasticity the former result also holds if the number of firms is held fixed

the implications of central bank transparency for uncertainty and disagreement abstract using survey data from 25 economies we provide evidence that greater transparency surrounding monetary policy reduces uncertainty of interest rates and inflation primarily by reducing uncertainty that is common to agents rather than disagreement between agents this suggests that studies that focus on disagreement as a proxy for uncertainty understate the benefits of monetary policy transparency the adoption of inflation targets and forward guidance are both associated with lower uncertainty although inflation targets have a stronger impact on reducing uncertainty than forward guidance moreover there are diminishing benefits from ever higher levels of transparency taken as a whole our results support the contention that clarity of communication is as important as the magnitude of transparency

market r d allocations when research paths are product specific a compared to the social optimum individual firms undertook too little rd b too many firms entered the competition to undertake rd2 c if the elasticity of demand were sufficiently low aggregate rd

precautionary portfolio behavior from a life cycle perspective abstract the literature on household asset accumulation draws a sharp distinction between short run precautionary motives to buffer consumption from annual income shocks and long run life cycle considerations under income certainty however estimates of shock persistence imply considerable career uncertainty we study long run precautionary motives for life cycle wealth accumulation and portfolios allowing for uncertain returns incomes and lifespan we separate the effects of various factors on mean and median asset holdings including education risk aversion household heterogeneity bequests impatience variance and serial correlation of income shocks numerical solutions are compared with data from the 1992 survey of consumer finances

ramsey tax rules for economies with imperfect competition abstract this paper derives optimal commodity tax rules for a general equilibrium model with imperfect competition to achieve this functions are constructed that describe the effects of taxation upon the equilibrium prices and profit levels of imperfectly competitive industries the use of these functions allows existing tax rules to be generalised to accommodate imperfect competition

does clarity of central bank communication affect credibility evidences considering governor specific effects central banks have made great efforts to increase transparency and accountability to the public since then studies seek empirical evidences about the effects of monetary policy communication over

existence of consistent conjectures reply arthur robson s excellent comment introduces a new formulation of the problem of consistent conjectures my reply uses the new formulation in order to resolve robson s troubling example of nonexistence and to make the problem clearer it also shows why my original approach was sensible only for the linear demand curve case a slightly more general approach used here has consistent conjectures in robson s quadratic inverse demand example

on strategic cost increases in a duopoly abstract this study determines whether duopolists can profit from imposed cost increases even if both firms are affected equally implicit in any analysis of strategic behavior is the assumption that firms are sufficiently sophisticated to anticipate the new industry equilibrium requiring each duopolist to have consistent conjectures abouts its rival s behavior we show that if the firms marginal cost curves are sufficiently flat increasing the slopes of these curves can raise profits the steeper marginal cost curves encourage regulatory coordination that is the rivals move closer to the joint profit maximizing outcome

monopolistic competition in the spirit of chamberlin special results the idea of large group monopolistic competition was first introduced by chamberlin in i 933 although a large literature has developed on this topic since that time it can be argued that few of the models which have been formulated really capture monopolistic competition in chamberlin s sense in a companion paper to this one hart i 983 a model was presented which it was claimed did satisfy the desiderata of large group monopolistic competition specifically the model had the property that i there were many firms producing differentiated commodities 2 each firm was negligible in the sense that it could ignore its impact on and hence reactions from other firms 3 free entry led to zero profit of operating firms but 4 each firm faced a downward sloping demand curve and hence equilibrium price exceeded marginal cost the model of hart i983 was quite general and only such issues as the existence and limiting properties of equilibrium were considered the purpose of the present paper is to analyse a special case of this model in greater detail and to consider in this context the old question of whether too few or too many brands are produced under monopolistic competition before embarking on the analysis however let me briefly indicate why i believe that there is a need for a new model of monopolistic competition further discussion of this may be found in hart i983 in the last few years a sizeable literature has developed on imperfect competition and product differentiation see for example dixit and stiglitz i977 lancaster i979 salop i979 and spence i976 in much of this literature see for example spence i976 markets of fixed finite size are considered where the entry of firms is limited by the existence of set up costs under these conditions only a finite number of firms can operate and hence firms will not be negligible in the sense of 2 in addition due to the integer problem operating firms will generally make strictly positive profits i e 3 is violated models of

precautionary saving in the small and in the large the theory of precautionary saving is shown to be isomorphic to the arrow pratt theory of risk aversion making possible the application of a large body of knowledge about risk aversion to precautionary saving and more generally to the theory of optimal choice under risk in particular a measure of the strength of the precautionary saving motive analogous to the arrow pratt measure of risk aversion is used to establish a number of new propositions about precautionary saving and to give a new interpretation of the dreze modigliani substitution effect copyright 1990 by the econometric society

accountability transparency and inflation targeting inflation targeting regimes define a performance measure for the central bank a regime that places a large small weight on achieving the target is analogous to a high low powered incentive scheme high powered incentive structures promote accountability but may distort stabilization policy the optimal power under inflation targeting is derived under perfect and imperfect information the fundamental trade off between accountability and stabilization depends on the degree of transparency defined as the ability to monitor the central bank s performance multiplicative uncertainty increases the optimal weight to place on achieving an inflation target

true monopolistic competition as a result of imperfect information the paper restates hart s 1985a 1985b definition of large group monopolistic competition distinguishes it from oligopolistic competition and raises the question of whether there are reasonable circumstances that give rise to true monopolistic competition as defined the purpose is to show that consumers imperfect information may create conditions that will turn an otherwise oligopolistic market into a truly monopolistically competitive one