On the welfare costs of business-cycle fluctuations and economic-growth variation in the 20th century and beyond

The main objective of this paper is to propose a novel setup that allows estimating separately the welfare costs of the uncertainty stemming from business-cycle uctuations and from economic-growth variation, when the two types of shocks associated with them (respectively,transitory and permanent shocks) hit consumption simultaneously. Separating these welfare costs requires dealing with degenerate bivariate distributions. Levis Continuity Theorem and the Disintegration Theorem allow us to adequately de ne the one-dimensional limiting marginal distributions. Under Normality, we show that the parameters of the original marginal distributions are not afected, providing the means for calculating separately the welfare costs of business-cycle uctuations and of economic-growth variation. Our empirical results show that, if we consider only transitory shocks, the welfare cost of business cycles is much smaller than previously thought. Indeed, we found it to be negative - -0:03% of per-capita consumption! On the other hand, we found that the welfare cost of economic-growth variation is relatively large. Our estimate for reasonable preference-parameter values shows that it is 0:71% of consumption US$ 208:98 per person, per year.

O impacto dos gastos com publicidade nas vendas das firmas: avaliação empírica.

Este trabalho tem por objetivo estimar um modelo empírico para relacionar os gastos em publicidade com a receita das firmas, de forma a servir como ferramenta de tomada de decisão, para isso vamos fazer um estudo de caso da indústria de telecomunicações. A Indústria de comunicação (publicidade) no Brasil, segundo dados do IBGE de 2008, é responsável por 4% do PIB, gerando receitas da ordem 115 bilhões de reais. Com 113 mil empresas que geram 711 mil empregos, ocupam 866 mil pessoas e pagam 11,8 bilhões em salários e encargos. No entanto, a maioria dos gestores de marketing declara não ter instrumentos para medir o impacto de suas ações no resultado das empresas. O modelo empírico será estimado tendo como base dados mensais dos serviços de ligações de longa distância nacional da Embratel para o período de janeiro de 2009 até dezembro de 2011. As informações quase sempre não disponíveis, só puderam ser usadas devido ao compromisso de confidencialidade. A partir de técnicas de cointegração, foi calculada a elasticidade de longo prazo da receita em relação aos gastos com publicidade e ao preço, assim com as respectivas velocidades de ajustamento aos desvios de curto prazo. Os resultados sugerem que a receita responde positivamente às variações dos gastos em publicidade, embora o percentual seja relativamente baixo, através do teorema de Dorfman-Steiner conseguimos indicar que o ponto ótimo da relação entre gastos com publicidade e a receita seria de aproximadamente 20%, respeitadas as limitações do modelo.

Incomplete contracts and the problem of social harm

We construct a model in which a first mover decides on its location before it knows the identity of the second mover; joint location results in a negative extemality. Contracts are inherently incomplete since the first mover's initial decision cannot be specified. We analyze several kinds of rights, including damages, injunctions, and rights to exclude (arising from covenants or land ownership). There are cases in which allocating any of these basic rights to the first mover-i.e., first-party rights-is dominated by second-party rights, and cases in which the reverse is true. A Coasian result (efficiency regardless of the rights allocation) only holds under a limited set of conditions. As corollaries of a theorem ranking the basic rights regimes, a number of results emerge contradicting conventional wisdom, including the relative inefficiency of concentrated land ownership and the relevance of the generator's identity. We conclude with a mechanism and a new rights regime that each yield the first best in all cases.

A notion of subgame perfect nash equilibrium under knightian uncertainty

We define a subgame perfect Nash equilibrium under Knightian uncertainty for two players, by means of a recursive backward induction procedure. We prove an extension of the Zermelo-von Neumann-Kuhn Theorem for games of perfect information, i. e., that the recursive procedure generates a Nash equilibrium under uncertainty (Dow and Werlang(1994)) of the whole game. We apply the notion for two well known games: the chain store and the centipede. On the one hand, we show that subgame perfection under Knightian uncertainty explains the chain store paradox in a one shot version. On the other hand, we show that subgame perfection under uncertainty does not account for the leaving behavior observed in the centipede game. This is in contrast to Dow, Orioli and Werlang(1996) where we explain by means of Nash equilibria under uncertainty (but not subgame perfect) the experiments of McKelvey and Palfrey(1992). Finally, we show that there may be nontrivial subgame perfect equilibria under uncertainty in more complex extensive form games, as in the case of the finitely repeated prisoner's dilemma, which accounts for cooperation in early stages of the game .

Beyond common priors

One property (called action-consistency) that is implicit in the common prior assumption (CPA) is identified and shown to be the driving force of the use of the CPA in a class of well-known results. In particular, we show that Aumann (1987)’s Bayesian characterization of correlated equilibrium, Aumann and Brandenburger (1995)’s epistemic conditions for Nash equilibrium, and Milgrom and Stokey (1982)’s no-trade theorem are all valid without the CPA but with action-consistency. Moreover, since we show that action-consistency is much less restrictive than the CPA, the above results are more general than previously thought, and insulated from controversies around the CPA.

Mid-auction information acquisition

This paper studies a model of a sequential auction where bidders are allowed to acquire further information about their valuations of the object in the middle of the auction. It is shown that, in any equilibrium where the distribution of the final price is atornless, a bidder's best response has a simple characterization. In particular, the optimal information acquisition point is the same, regardless of the other bidders' actions. This makes it natural to focus on symmetric, undominated equilibria, as in the Vickrey auction. An existence theorem for such a class of equilibria is presented. The paper also presents some results and numerical simulations that compare this sequential auction with the one-shot auction. 8equential auctions typically yield more expected revenue for the seller than their one-shot counterparts. 80 the possibility of mid-auction information acquisition can provide an explanation for why sequential procedures are more often adopted.

Revisiting modern portfolio theory

This paper revisits Modern Portfolio Theory and derives eleven properties of Efficient Allocations and Portfolios in the presence of leverage. With different degrees of leverage, an Efficient Portfolio is a linear combination of two portfolios that lie in different efficient frontiers - which allows for an attractive reinterpretation of the Separation Theorem. In particular a change in the investor risk-return preferences will leave the allocation between the Minimum Risk and Risk Portfolios completely unaltered - but will change the magnitudes of the tactical risk allocations within the Risk Portfolio. The paper also discusses the role of diversification in an Efficient Portfolio, emphasizing its more tactical, rather than strategic character