An alternative direct proof of Gibbard’s random dictatorship theorem

We present an alternative proof of the Gibbards random dictatorship theorem with ex post Pareto optimality. Gibbard(1977) showed that when the number of alternatives is finite and larger than two, and individual preferences are linear (strict), a strategy-proof decision scheme (a probabilistic analogue of a social choice function or a voting rule) is a convex combination of decision schemes which are, in his terms, either unilateral or duple. As a corollary of this theorem (credited to H. Sonnenschein) he showed that a decision scheme which is strategy-proof and satisfies ex post Pareto optimality is randomly dictatorial. We call this corollary the Gibbards random dictatorship theorem. We present a proof of this theorem which is direct and follows closely the original Gibbards approach. Focusing attention to the case with ex post Pareto optimality our proof is more simple and intuitive than the original Gibbards proof.Received: 15 October 2001, Accepted: 23 May 2003, JEL Classification: D71, D72Yasuhito Tanaka: The author is grateful to an anonymous referee and the Associate editor of this journal for very helpful comments and suggestions. And this research has been supported by a grant from the Zengin Foundation for Studies on Economics and Finance in Japan.     

On the Validity of the Random Lottery Incentive System

The random lottery incentive system is widely used in experimental economics to motivate subjects. This paper investigates its validity. It reports three experiments which compare responses given to decision tasks which are embedded in random lottery designs with responses in single choice designs in which each subject faces just one task for real. The experiments were designed to detect cross-task contamination effects in the random lottery treatment. No significant differences between treatments, and no significant contamination effects, were found. Over the three experiments, observed differences between the treatments are adequately explained as sampling variation.     

A New Solution to the Random Assignment Problem

A random assignment is ordinally efficient if it is not stochastically dominated with respect to individual preferences over sure objects. Ordinal efficiency implies (is implied by) ex post (ex ante) efficiency. A simple algorithm characterizes ordinally efficient assignments: our solution, probabilistic serial (PS), is a central element within their set. Random priority (RP) orders agents from the uniform distribution, then lets them choose successively their best remaining object. RP is ex post, but not always ordinally, efficient. PS is envy-free, RP is not; RP is strategy-proof, PS is not. Ordinal efficiency, Strategyproofness, and equal treatment of equals are incompatible. Journal of Economic Literature Classification Numbers: C78, D61, D63.     

Analysis for radical design

This paper examines a technique suitable for monitoring and analyzing systemic change in technology. Technological changes increasingly stem from the novel recombination of existing technologies. Changes are multitudinous. Therefore, new techniques are needed for analyzing technology architecture. A literature review of related work in the field of technology opportunities analysis is presented. We consider a possible, radically decentralized context for the conduct of future design. A case study of new technology architecture in the information technology domain is presented. An analytical method involving mining weighted graphs from technology archives is presented. The role of this new method in a context of distributed decision-making and design is presented.     

A MODEL OF OPTIMAL CONSUMPTION UNDER LIQUIDITY RISK WITH RANDOM TRADING TIMES

We consider a portfolio/consumption choice problem in a market model with liquidity risk. The main feature is that the investor can trade and observe stock prices only at exogenous Poisson arrival times. He may also consume continuously from his cash holdings, and his goal is to maximize his expected utility from consumption. This is a mixed discrete/continuous stochastic control problem, non‐standard in the literature. The dynamic programming principle leads to a coupled system of Integro‐Differential Equations (IDE), and we provide a convergent numerical algorithm for the resolution to this coupled system of IDE. Several numerical experiments illustrate the impact of the restricted liquidity trading opportunities, and we measure in particular the utility loss with respect to the classical Merton consumption problem.     

Mixed Hidden Markov Models for Longitudinal Data: An Overview

In this paper we review statistical methods which combine hidden Markov models (HMMs) and random effects models in a longitudinal setting, leading to the class of so‐called mixed HMMs. This class of models has several interesting features. It deals with the dependence of a response variable on covariates, serial dependence, and unobserved heterogeneity in an HMM framework. It exploits the properties of HMMs, such as the relatively simple dependence structure and the efficient computational procedure, and allows one to handle a variety of real‐world time‐dependent data. We give details of the Expectation‐Maximization algorithm for computing the maximum likelihood estimates of model parameters and we illustrate the method with two real applications describing the relationship between patent counts and research and development expenditures, and between stock and market returns via the Capital Asset Pricing Model.     

订货问题的随机库存模型

建立了需求量是连续型随机变量为单周期的随机库存模型,从而给企业管理人员提供了定量决策的理论依据。     

RESILIENCE TO CONTAGION IN FINANCIAL NETWORKS

We derive rigorous asymptotic results for the magnitude of contagion in a large counterparty network and give an analytical expression for the asymptotic fraction of defaults, in terms of network characteristics. Our results extend previous studies on contagion in random graphs to inhomogeneous‐directed graphs with a given degree sequence and arbitrary distribution of weights. We introduce a criterion for the resilience of a large financial network to the insolvency of a small group of financial institutions and quantify how contagion amplifies small shocks to the network. Our results emphasize the role played by “contagious links” and show that institutions which contribute most to network instability have both large connectivity and a large fraction of contagious links. The asymptotic results show good agreement with simulations for networks with realistic sizes.     

Finite sample performance of specification tests for correlated random effects quantile panel regressions

We investigate the finite sample performance of the Abrevaya and Dahl (2008) test for coefficient heterogeneity for a correlated random effects ‘mean’ (CREM) panel quantile regression estimator. We assess size and power of the test over a range of sample sizes and panel dimensions. The test is undersized for small-to-moderate sample sizes and displays low power even with a high degree of heteroscedasticity. Size and power improve substantially in larger samples. Our results provide insight for applied researchers.     

论适应性预期下中国投资者对股市主观概率的测定

股市的涨跌离不开投资者的预期,在适应性预期的条件下,我们可以测定投资者对股市看法的主观概率。通过对我国股市十几年的数据分析,可以发现我国投资者对股市看法的主观概率是有规律的,投资者不会连续预测股市好转也不会连续预测股市恶化,一般都是以不超过两年为一个好转或恶化的阶段。