Sorting and Decentralized Price Competition

We investigate the role of search frictions in markets with price competition and how it leads to sorting of heterogeneous agents. There are two aspects of value creation: the match value when two agents actually trade and the probability of trading governed by the search technology. We show that positive assortative matching obtains when complementarities in the former outweigh complementarities in the latter. This happens if and only if the match‐value function is root‐supermodular, that is, its nth root is supermodular, where n reflects the elasticity of substitution of the search technology. This condition is weaker than the condition required for positive assortative matching in markets with random search.     

Assortative Matching and Search

In Becker's (1973) neoclassical marriage market model, matching is positively assortaive if types are complements: i.e., match output f(x, y) is supermodular in x and y. We reprise this famous result assuming time‐intensive partner search and transferable output. We prove existence of a search equilibrium with a continuum of types, and then characterize matching. After showing that Becker's conditions on match output no longer suffice for assortative matching, we find sufficient conditions valid for any search frictions and type distribution: supermodularity not only of output f, but also of log f_x and log f_xy. Symmetric submodularity conditions imply negatively assortative matching. Examples show these conditions are necessary.     

Marriage,Labor Supply,and Home Production

We develop a search model of marriage where men and women draw utility from private consumption and leisure, and from a non‐market good that is produced in the home using time resources. We condition individual decisions on wages, education, and an index of family attitudes. A match‐specific, stochastic bliss shock induces variation in matching given wages, education, and family values, and triggers renegotiation and divorce. Using BHPS (1991–2008) data, we take as given changes in wages, education, and family values by gender, and study their impact on marriage decisions and intrahousehold resource allocation. The model allows to evaluate how much of the observed gender differences in labor supply results from wages, education, and family attitudes. We find that family attitudes are a strong determinant of comparative advantages in home production of men and women, whereas education complementarities induce assortative mating through preferences.     

An Econometric Model of Network Formation With Degree Heterogeneity

I introduce a model of undirected dyadic link formation which allows for assortative matching on observed agent characteristics (homophily) as well as unrestricted agent‐level heterogeneity in link surplus (degree heterogeneity). Like in fixed effects panel data analyses, the joint distribution of observed and unobserved agent‐level characteristics is left unrestricted. Two estimators for the (common) homophily parameter, β₀, are developed and their properties studied under an asymptotic sequence involving a single network growing large. The first, tetrad logit (TL), estimator conditions on a sufficient statistic for the degree heterogeneity. The second, joint maximum likelihood (JML), estimator treats the degree heterogeneity {A_i0}_{i = 1}^N as additional (incidental) parameters to be estimated. The TL estimate is consistent under both sparse and dense graph sequences, whereas consistency of the JML estimate is shown only under dense graph sequences.     

Income Maintenance and Labor Force Participation

The paper studies the optimal tax‐subsidy schedules in an economy where the only decision of the agents is to work, or not, with an application to the case of France. Given an income guarantee provided by the welfare state, the tax schedule that maximizes government revenue provides a benchmark, the Laffer bound, above which it is inefficient to tax. In fact, under mild conditions, a feasible allocation is second best optimal if and only if the associated taxes are lower than the Laffer bound. The only restriction that efficiency puts on the shape of the tax scheme is this upper Laffer bound. The Laffer tax scheme itself can be computed from the joint distribution of the agents' productivities and work opportunity costs. Depending on the economy, it can take widely different forms, and exhibit, for instance, negative marginal tax rates. After estimating the joint distribution of productivities and work opportunity costs on French data, I compute the Laffer bound for two subpopulations, single women and married women with two children or more. Quite surprisingly, the actual incentives to work appear to be very close to the bound.     

Equilibrium Bias of Technology

This paper presents three sets of results about equilibrium bias of technology. First, I show that when the menu of technological possibilities only allows for factor‐augmenting technologies, the increase in the supply of a factor induces technological change relatively biased toward that factor—meaning that the induced technological change increases the relative marginal product of the factor becoming more abundant. Moreover, this induced bias can be strong enough to make the relative marginal product of a factor increasing in response to an increase in its supply, thus leading to an upward‐sloping relative demand curve. I also show that these results about relative bias do not generalize when more general menus of technological possibilities are considered. Second, I prove that under mild assumptions, the increase in the supply of a factor induces technological change that is absolutely biased toward that factor—meaning that it increases its marginal product at given factor proportions. The third and most important result in the paper establishes the possibility of and conditions for strong absolute equilibrium bias—whereby the price (marginal product) of a factor increases in response to an increase in its supply. I prove that, under some regularity conditions, there will be strong absolute equilibrium bias if and only if the aggregate production function of the economy fails to be jointly concave in factors and technology. This type of failure of joint concavity is possible in economies where equilibrium factor demands and technologies result from the decisions of different agents.     

Embedded Networks and Suboptimal Resource Matching in Alliance Formations

Interest has been growing in alliance networks, and research has demonstrated several advantages of embedded networks, including joint problem solving. How embedded networks function as social capital and promote alliance formation has also been explored. However, less is known about constraints that they impose on firms’ extensive search for partners. In this study, we advance our understanding of the downsides of embedded networks by proposing that embedded networks facilitate alliance formations, but they may also cause suboptimal resource matching in alliance formations. Specifically, we predict that, in alliances where initial resource matching is more important than ex post collaborative activities, suboptimal resource matching is more likely when firms ally with partners with which they have pre‐existing direct or indirect ties and that such alliances decrease firm‐level resource utilization performance in operations. Using codeshare alliance data from the global airline industry, we find support for our predictions.     

JOB MARKET SIGNALING OF RELATIVE POSITION,OR BECKER MARRIED TO SPENCE

This paper considers a matching model of the labor market where workers, who have private information on their quality, signal to firms that also differ in quality. Signals allow assortative matching in which the highest‐quality workers send the highest signals and are hired by the best firms. Matching is considered both when wages are rigid (nontransferable utility) and when they are fully flexible (transferable utility). In both cases, equilibrium strategies and payoffs depend on the distributions of worker and firm types. This is in contrast to separating equilibria of the standard model, which do not respond to changes in supply or demand. With sticky wages, despite incomplete information, equilibrium investment in education by low‐ability workers can be inefficiently low, and this distortion can become worse in a more competitive environment. In contrast, with flexible wages, greater competition improves efficiency.     

The shadow of the past: how experience affects behavior in an iterated prisoner’s dilemma experiment

We study the development of cooperation in a repeated prisoner’s dilemma experiment with teams as players, unknown length and unknown continuation probability as it could happen between traders regularly. To characterize real-world frictions our players are rematched with a new team twice. In such a situation—often found outside the laboratory—agents can get an idea on the likely duration of future interactions by relying on prior experience. Our main finding is that participants apparently transform the infinite-horizon situation into a finite-horizon situation. Not only do we observe decay in cooperation but also unraveling towards the end of a matching. We found a pronounced restart effect of cooperation that induces a steady rise in average cooperation over matchings. Such an effect is not observed after the unexpected continuation of the third match. Stable cooperation paths of considerable length are induced when both players start the matching with joint cooperative moves. We can draw some interesting conclusions from the behavior of the partners for commercial market situations.     

Zero Expected Wealth Taxes: A Mirrlees Approach to Dynamic Optimal Taxation

In this paper, I consider a dynamic economy in which a government needs to finance a stochastic process of purchases. The agents in the economy are privately informed about their skills, which evolve stochastically over time; I impose no restriction on the stochastic evolution of skills. I construct a tax system that implements a symmetric constrained Pareto optimal allocation. The tax system is constrained to be linear in an agent's wealth, but can be arbitrarily nonlinear in his current and past labor incomes. I find that wealth taxes in a given period depend on the individual's labor income in that period and previous ones. However, in any period, the expectation of an agent's wealth tax rate in the following period is zero. As well, the government never collects any net revenue from wealth taxes.     

Job Matching and the Wage Distribution

This paper brings together the microeconomic‐labor and the macroeconomic‐equilibrium views of matching in labor markets. We nest a job matching model à la Jovanovic (1984) into a Mortensen and Pissarides (1994)‐type equilibrium search environment. The resulting framework preserves the implications of job matching theory for worker turnover and wage dynamics, and it also allows for aggregation and general equilibrium analysis. We obtain two new equilibrium implications of job matching and search frictions for wage inequality. First, learning about match quality and worker turnover map Gaussian output noise into an ergodic wage distribution of empirically accurate shape: unimodal, skewed, with a Paretian right tail. Second, high idiosyncratic productivity risk hinders learning and sorting, and reduces wage inequality. The equilibrium solutions for the wage distribution and for the aggregate worker flows—quits to unemployment and to other jobs, displacements, hires—provide the likelihood function of the model in closed form.     

Money as a Unit of Account

We develop a theory that rationalizes the use of a dominant unit of account in an economy. Agents enter into non‐contingent contracts with a variety of business partners. Trade unfolds sequentially in credit chains and is subject to random matching. By using a dominant unit of account, agents can lower their exposure to relative price risk, avoid costly default, and create more total surplus. We discuss conditions under which it is optimal to adopt circulating government paper as the dominant unit of account, and the optimal choice of “currency areas” when there is variation in the intensity of trade within and across regions.     

考虑稳定匹配条件的双边满意匹配决策方法

双边匹配问题是指如何在两个不相交的主体集合中依据各主体针对潜在匹配对象给出的偏好信息来确定合适的匹配结果,其在经济管理领域中存在着大量的实际背景,是许多学者关注的研究课题。在本文中,针对双边主体给出偏好序值信息的双边匹配问题,给出了一种考虑稳定匹配条件的双边满意匹配决策方法。首先给出了双边匹配、稳定匹配和满意匹配的相关概念;然后考虑到稳定匹配条件,并以双边主体满意度最大为目标,构建了多目标双边匹配优化模型;进一步地,采用线性加权法将多目标优化模型转换为单目标优化模型,并通过求解优化模型来获得最优匹配结果。最后,通过一个算例说明了本文提出方法的实用性和有效性。     

一类幂指数求和型生产函数的应用研究:基于中国31省市房地产行业数据的实证分析

生产函数理论是计量经济学应用的重要部分。不论是理论研究和实证分析,经济学家们都广泛借助生产函数模型来研究经济增长、外部性和报酬递增等问题。通过对柯布-道格拉斯生产函数的优缺点进行分析,得到了一类可描述复杂生产过程的幂指数求和型生产函数。给出了这类幂指数求和型生产函数若干性质的计算公式。探讨了这类幂指数求和型生产函数的参数估计方法。最后基于2005年我国31省市房地产业数据建立新型生产函数,通过计算得到了资本与劳动力的产出弹性分别为0.67与0.33。     

基于悲观度的双边匹配决策问题研究

双边匹配决策问题一直是经济管理和计算几何等领域研究的热点和难点问题之一。针对双边主体偏好信息为序值的双边匹配决策问题,提出基于悲观度的新方法,给出具有序值形式信息的双边匹配决策问题的描述,引入能够反映功利型中介悲观度的满意度和支付的计算公式。在此基础上,考虑到匹配主体对之间的满意度和功利型中介的收益,构建求解双边匹配决策问题的多目标优化模型。运用基于隶属函数的加权和方法将多目标优化模型转化为单目标优化模型,运用Hungarian法进行求解获得双边匹配方案,通过算例说明给出方法的有效性。计算结果表明,悲观度取值不同,运用该方法获得的双边匹配方案也可能会不同,即双边匹配方案能反映不同功利型中介的不同风险偏好。     

Regional Labour Market Matching Functions and Efficiency Analysis

Abstract. Stochastic production frontiers are used for estimating regional matching functions where unemployment outflow is ‘produced’ by the unemployed and vacancies. The frontier is estimated using regional panel data from Finland from 1988 to 1997 and the Battese and Coelli frontier model, where the explanatory factors are included in the inefficiency term. The stochastic frontier matching function has constant returns, whereas in OLS estimation with fixed effects the returns are slightly increasing. Unemployment and vacancies in neighbouring regions have a spillover effect on efficiency. Excess job reallocation in a region deteriorates matching efficiency. The decomposition of total factor productivity change in matching to efficiency change and change in matching technology is also investigated by interpreting the matching frontier as a distance function and using Malmquist indexes. There is a downward trend in the technology, but short‐term variations are dominated by cyclical changes in efficiency.     

Investment and Competitive Matching

We study markets in which agents first make investments and are then matched into potentially productive partnerships. Equilibrium investments and the equilibrium matching will be efficient if agents can simultaneously negotiate investments and matches, but we focus on markets in which agents must first sink their investments before matching. Additional equilibria may arise in this sunk‐investment setting, even though our matching market is competitive. These equilibria exhibit inefficiencies that we can interpret as coordination failures. All allocations satisfying a constrained efficiency property are equilibria, and the converse holds if preferences satisfy a separability condition. We identify sufficient conditions (most notably, quasiconcave utilities) for the investments of matched agents to satisfy an exchange efficiency property as well as sufficient conditions (most notably, a single crossing property) for agents to be matched positive assortatively, with these conditions then forming the core of sufficient conditions for the efficiency of equilibrium allocations.     

Return predictability and social dynamics

The ability to predict stock returns from financial ratios is a long-standing but still controversial topic. There is ongoing debate about the empirical evidence as well as about appropriate theoretical explanations. We provide evidence from a simulated economy that local, social interaction among agents is remarkably successful in matching several established empirical facts. We find significant return predictability at various forecast horizons, absence of dividend growth predictability, high persistence in dividend yields, and absence of significant return autocorrelations. Our results suggest that social dynamics are a simple, intuitively appealing and successful way to explain predictability.     

Can we have global ethics in a global economy?

With the collapse of the bi-polar world, we live in an increasingly integrated global economy, which includes economic, political, and cultural dimensions. We argue that there is a need for a global ethic commensurate with a global economy, based upon the claims of interdependence, economic insecurity, multiculturalism, and shared problems. The need to identify some common cross-cultural ethical norms is asserted as an important component of a global ethic and various sources and means for such identification are proposed. Finally, we propose reasons why global corporations ought to embrace cross-cultural ethical norms within their own corporate ethics.A version of this paper was first delivered at a joint business faculty seminar co-sponsored by Anadolu University and Baldwin-Wallace College, held at Anadolu University, Eskischir, Turkey, in December 1992. I express deep gratitude to my losts from Aanadolu University and special thanks to Professor Selva Herekman, who painstakingly translated my English text into Turkish.