Equilibrium in a reinsurance market with short sale constraints

Summary. This paper deals with the existence of equilibrium in a dynamic reinsurance market with short sale constraints, driven by a marked point process, as studied in Bernis and Jouini (2001). We use the set of reinsurance treaties as consumption set, which is the positive orthant of some Banach lattice that can be identified to a space of martingales, . The properness of preferences is a key assumption for us to prove the existence of an equilibrium. We provide a sufficient condition for the preferences to be proper in term of loading factor of the reinsurance premium. Received: June 15, 2000; revised version: May 17, 2001     

PASSPORT OPTIONS

We relate the theory of passport options with general principles from martingale theory as well as with the theory of Bessel processcs. The calculation of the price of a passport option leads to an equality between two norms on continuous martingales. We also solve the discrete time case for passport options.     

Cognitive Theory and Moral Behavior: The Contribution of F. A. Hayek to Business Ethics

This paper shows how business ethics as a concept may be approached from a cognitive viewpoint. Following F. A. Hayek's cognitive theory, I argue that moral behavior evolves and changes because of individual perception and action. Individual moral behavior becomes a moral rule when prominently displayed by members of a certain society in a specific situation. A set of moral rules eventually forms the ethical code of a society, of which business ethics codes are only a part. By focusing on the concept of "limited" or "dispersed knowledge" that underlies the cognitive approach, I show that universal ethical norms that should lead to defined outcomes cannot exist. This approach moreover shows the limits of deliberate rule-setting. Attempts to deliberately impose universal ethical rules on societies may turn out to be harmful for societal development and lead to an abuse of governmental power.     

Maximum likelihood estimation of the double exponential jump-diffusion process

The double exponential jump-diffusion (DEJD) model, recently proposed by Kou (Manage Sci 48(8), 1086–1101, 2002) and Ramezani and Zeng (http://papers.ssrn.com/sol3/papers.cfm?abstract_id=606361, 1998), generates a highly skewed and leptokurtic distribution and is capable of matching key features of stock and index returns. Moreover, DEJD leads to tractable pricing formulas for exotic and path dependent options (Kou and Wang Manage Sci 50(9), 1178–1192, 2004). Accordingly, the double exponential representation has gained wide acceptance. However, estimation and empirical assessment of this model has received little attention to date. The primary objective of this paper is to fill this gap. We use daily returns for the S&;P-500 and the NASDAQ indexes and individual stocks, in conjunction with maximum likelihood estimation (MLE) to fit the DEJD model. We utilize the BIC criterion to assess the performance of DEJD relative to log-normally distributed jump-diffusion (LJD) and the geometric brownian motion (GBM). We find that DEJD performs better than these alternatives for both indexes and individual stocks.     

高业绩企业群体中的弱企业效应研究——以2002—2006中国500强企业为样本的分析

企业绩效差异的主要影响因素来自产业层面还是企业层面一直是企业战略理论关注的基本问题。自从Schmalensee(1985)应用方差分析技术得出其效应分布结论以来,对此问题的研究一直延续至今。战略管理学者较一致的结论是企业层面因素即企业效应是影响企业业务绩效差异的主要因素。然而,本文所作的数据分析表明,在我国高业绩企业群中,企业因素并不是绩效总差的主要解释因素,其解释能力弱于产业因素,即使是在充分竞争领域也是如此。通过对一组反馈回路的考察,本文分析了在我国弱企业效应产生和持续的原因、条件,并据此提出了一种新的关于企业经营策略性质的分类方法。     

Social Position and Behaviour: A Formalization

Modern society has witnessed anever-increasing development in the social sciences;partly due to changes in mentality, and partly due tothe growing requirements of the economic and political world – requirements which frequently takeon the guise of necessity, as for instance in thecases of market research and electoral opinion polls.Such development has produced an increasing paralleldemand for mathematical accuracy and exactitude inthese fields.The intention here is to rationalize the basic logicand methodology of the sociological procedure; anintention, it is hoped, which could be influential inimproving practical sociological work by rendering itmore comprehensible. This requires the employment offairly sophisticated mathematical and statisticalnotions.Section 1 outlines the definitions considered essential for the rationalization of the basiclogic framework previously described.Section 2 discusses the general concept of statisticalvariance. Section 3 introduces the notion of ``heterogeneity'and offers several propositions linked to this concept.Section 5 revolves around the notion of ``inaccuracy'.Section 6 presents a theorem relating to theimmersion of metric spaces in Banach spaces, andshows how the theorem can be used to constructtheoretically satisfactory immersion algorithms.Section 7 together with the material, which ispreviously introduced in Section 4, outlines thecluster analysis and the principal components methodologies.     

Adult Outcomes for Children of Teenage Mothers

Using data from the British Household Panel Survey, this study examines the relationship between several outcomes in early adulthood (e.g. education, inactivity, earnings and health) and being born to a teenage mother. Besides standard cross‐sectional multivariate regression estimates, we also present evidence from non‐parametric estimates and from estimates that account for unmeasured family background heterogeneity by comparing siblings born to the same mother who timed their births at different ages. Regardless of the econometric technique, being born to a teenage mother is usually associated with worse outcomes. An important channel of transmission of this adverse effect is childhood family structure, which plays a more powerful role than childhood family poverty. Albeit smaller, some of the detrimental effects are also found for children of mothers who gave birth in their early 20s.     

Collaboration,motivation, and the size of organizations

We present an analytical model of an organization that offers operational drivers of limits on team size. The model trades off benefits from collaborative problem solving against the disadvantages of diminishing motivation when groups get large. Collaboration is represented as parallel employee activity combined with frequent sharing of partial information, with a resulting superlinear performance increase over team size. Motivation is modeled by team members periodically setting an effort level either to contribute to the best of their ability or to “cruise”; at the minimum level not recognizable as shirking. Each individual decision is limited by bounded rationality based on team rewards, the time horizon of team interaction, and individual expectations about colleagues’ behavior. The decision collapses to a simple “barrier rule”;. Work hard when a certain “barrier percentage”; of team members work hard, and otherwise shirk. The influence of team size on this barrier percentage depends on the extent of benefits from collaboration: As long as performance increases quadratically with team size, the increased benefits resulting from collaboration exactly balance the temptation to shirk, with the barrier percentage approaching a fixed limit for large team sizes. As soon as the performance increase slows to anything less than quadratic, shirking eventually sets in and limits the possible size of the team. This implies that cooperation is sustainable in large organizational units, provided the problem‐solving processes used are powerful enough to ensure sufficient performance increases. Thus, effective problem‐solving methods are of double value, improving direct productivity and mitigating the social dilemma from team production. A manager should enlarge his or her organization up to the minimum of the limit set by the cooperation barrier and the exogenous performance limit.     

Knowledge Synthesis and Innovative Logistics Processes: Enhancing Operational Flexibility and Performance

Research results are presented providing an empirical examination of the impact of knowledge synthesis and innovative logistics processes on operational flexibility. The research is theoretically grounded in the resource‐based view of the firm, augmented with the knowledge‐based view. Knowledge synthesis and innovative logistics processes are proposed as key resources in the development of an important logistics capability: operational flexibility. A structural model analysis of survey data collected from logistics executives supports the proposed relationships and indicates that innovative logistics processes can lead to greater operational flexibility. Operational flexibility is also shown to lead to higher levels of logistics performance.     

ARBITRAGE BOUNDS FOR PRICES OF WEIGHTED VARIANCE SWAPS

We develop a theory of robust pricing and hedging of a weighted variance swap given market prices for a finite number of co‐maturing put options. We assume the put option prices do not admit arbitrage and deduce no‐arbitrage bounds on the weighted variance swap along with super‐ and sub‐replicating strategies that enforce them. We find that market quotes for variance swaps are surprisingly close to the model‐free lower bounds we determine. We solve the problem by transforming it into an analogous question for a European option with a convex payoff. The lower bound becomes a problem in semi‐infinite linear programming which we solve in detail. The upper bound is explicit. We work in a model‐independent and probability‐free setup. In particular, we use and extend Föllmer's pathwise stochastic calculus. Appropriate notions of arbitrage and admissibility are introduced. This allows us to establish the usual hedging relation between the variance swap and the “log contract” and similar connections for weighted variance swaps. Our results take the form of a FTAP: we show that the absence of (weak) arbitrage is equivalent to the existence of a classical model which reproduces the observed prices via risk‐neutral expectations of discounted payoffs.