Modeling and supporting task-oriented group processes: Purposeful complex adaptive systems and Evolutionary Systems Design

Evolutionary Systems Design (ESD) is a universal general problem solving, formal modeling, design framework for purposeful complex adaptive systems (PCAS) and processes, i.e., task-oriented group processes. These processes constitute policy making, group decision, negotiation, and multiagent problem solving with human and/or artificial agents. ESD is also a framework for computer group support systems (GSS) that support these processes. The ESD general framework can be applied to define and solve specific problems. In this article the ESD framework is presented and illustrated by example. The article provides background for ESD computer implementations discussed in two other related articles (Lewis and Shakun 1996; Bui and Shakun 1996).     

中国上市公司内外融资的顺序偏好

文章指出,对中国上市公司中的股份异质公司而言,若不考虑关联交易因素,内源融资逊色于外源融资,其所偏爱的股利政策为现金分红,这意味着中国证券监督管理委员会将现金分红作为上市公司申请配股或增发先决条件的现行规定可能并不妥当,加强对上市公司关联交易的监管才是问题的根本。在有报告盈余的情况下,这类公司会趋向于大规模派发现金股利,除非其报告盈余存在虚假或日后存在向其控股股东输送利润的可能,因此投资者及相关政府部门可利用这一特性低成本地甄别其企业会计报表的真伪及未来发生非对等关联交易的可能性。     

Option Pricing with Heterogeneous Expectations

This paper re-derives the finite mixture option pricing model of Ritchey (1990), based on the assumption that the option investors hold heterogeneous expectations about the parameters of the lognormal process of the underlying asset price. By proving that the model admits no riskless arbitrage, this paper justifies that the entire family of finite mixture of lognormal distributions is a desirable candidate set for recovering the risk-neutral probability distributions from contemporaneous options quotes. The parametric method derived from the model is significantly simpler than the nonparametric method of Rubinstein (1994) for recovering the risk-neutral probability distributions from contemporaneous option prices.     

Evaluating the length of stay and value of time in a pediatric emergency department with two models by comparing two different albuterol delivery systems

Abstract

Objective:

Asthma is one of the most common childhood illnesses and accounts for a substantial amount of pediatric emergency department visits. Historically, acute exacerbations are treated with a beta agonist via nebulizer therapy (NEB). However, with the advent of the spacer, the medication can be delivered via a metered dose inhaler (MDI?+?S) with the same efficacy for mild-to-moderate asthma exacerbations. To date, no study has been done to evaluate emergency department (ED) length of stay (LOS) and opportunity cost between nebulized vs MDI?+?S. The objective of this study was to compare ED LOS and associated opportunity cost among children who present with a mild asthma exacerbation according to the delivery mode of albuterol: MDI?+?S vs NEB.

Methods:

A structured, retrospective cross-sectional study was conducted. Medical records were reviewed from children aged 1–18 years treated at an urban pediatric ED from July 2007 to June 2008 with a discharge diagnosis International Classification of Disease-9 of asthma. Length of stay was defined: time from initial triage until the time of the guardian signature on the discharge instructions. An operational definition was used to define a mild asthma exacerbation; those patients requiring only one standard weight based albuterol treatment. Emergency department throughput time points, demographic data, treatment course, and delivery method of albuterol were recorded.

Results:

Three hundred and four patients were analyzed: 94 in the MDI?+?S group and 209 in the NEB group. Mean age in years for the MDI?+?S group was 9.57 vs 5.07 for the NEB group (p?<?0.001). The percentage of patients that received oral corticosteroids was 39.4% in the MDI?+?S group vs 61.7% in the NEB group (p?<?0.001). There was no difference between groups in: race, insurance status, gender, or chest radiographs. The mean ED LOS for patients in the MDI?+?S group was 170 minutes compared to 205 minutes in the NEB group. On average, there was a 25.1 minute time savings per patient in ED treatment time (p?<?0.001; 95% CI?=?3.8–31.7). Significant predictors of outcome for treatment time were chest radiograph, steroids, and treatment mode. Opportunity cost analysis estimated a potential cost savings of $213,532 annually using MDI?+?S vs NEB.

Conclusion:

In mild asthma exacerbations, administering albuterol via MDI?+?S decreases ED treatment time when compared to administering nebulized albuterol. A metered dose inhaler with spacer utilization may enhance opportunity cost savings and decrease the left without being seen population with improved throughput.

Limitations:

The key limitations of this study include its retrospective design, the proxy non-standard definition of mild asthma exacerbation, and the opportunity cost calculation, which may over-estimate the value of ED time saved based on ED volume.     

Asset allocation and multivariate position based trading

I add a second risky asset and a risk free bond to the univariate artificial market investigated by Lux and Marchesi (Int J Theor Appl Finance 3(4):675–702, 2000), keeping track of traders aggregate positions and wealth. Asset allocation and security selection are modeled as separate decision processes, as is common practice in financial institutions. Introducing position based trading avoids inconsistencies in traders inventories resulting from the order based setup of the original model, while preserving its ability to reproduce the stylized facts of financial return series.      

异质性企业出口行为的实证研究——基于中国企业面板数据

在近年兴起的新—新贸易理论中,出口行为与企业生产率之间的双向因果关系的实证研究逐渐成为主要的热点领域。许多学者用不同国家企业数据验证了自我选择效应和出口学习效应两个逻辑相反的假设。我们利用中国企业的微观层面数据对该命题进行验证。结果表明,自我选择效应显著,而出口学习效应不显著。最后在分析中国企业国际化行为特征的基础上,给出政策建议。     

Export Intensity and Plant Characteristics: What Can We Learn from Quantile Regression?

Using quantile regression and a rich cross section data set for German manufacturing plants this paper documents that the impact of plant characteristics on export activities varies along the conditional size distribution of the export/sales ratio. For example, firm size is statistically significant at a conventional level for the 0.25 quantile only; branch plant status matters at the upper tail of the conditional distribution of the export/sales ratio only; the craft shop dummy is only significant for the very top quantile; and patents do not matter at the very lower end of the conditional distribution of export over sales. This has implications both for understanding what makes a successful exporter, and for the design of policy measures with a focus on supporting exporters. JEL no. F10, D21, L60     

Are 18 Holes Enough for Tiger Woods?

This article addresses the selection problem in promotion tournaments. I consider a situation with heterogeneous employees and ask whether an employer might be interested in repeating a promotion tournament. On the one hand, this yields a reduction in uncertainty over the employees’ abilities. On the other hand, there are costs if a workplace stays vacant.     

Fiscal policy,wealth divergence,and lifetime utility

Using a two-country dynamic optimization model where the less patient country decumulates and the more patient one accumulates wealth, we analyze spillover effects of lump-sum and consumption taxes. A lump-sum tax on a country definitely harms the other country through a change in the rate of interest. A lump-sum tax on either country always improves the less patient country's asset position. A consumption tax has no spillover effect, although it is Pareto-inferior. Applying these results into a closed-country context with heterogeneous agents, we also discuss policy implications of a discriminatory tax.     

基于中国经验重构新新贸易理论的分析框架

异质性企业贸易模型是新新贸易理论的基本分析框架,该模型从企业生产率异质性角度分析企业出口的决定因素,得到企业拥有高生产率是保证其出口的重要条件,从而出口企业的生产率要高于内销企业的结论。不过,对中国企业的经验研究却发现,出口企业的生产率未必高于内销企业,甚至低于内销企业,即中国出口企业存在"生产率悖论"。目前,对于"生产率悖论"的研究主要集中于经验分析,并没有提出一个合理解释该现象的理论模型。文章从扩展异质性企业贸易模型的角度,建立了一个旨在解释"生产率悖论"的数理模型。尽管该模型对"生产率悖论"具有解释作用,但是并没有否定生产率对企业出口的作用。文章进一步使用较新的LP方法计算了中国制造业企业的生产率并运用统计法检验了出口企业"生产率悖论"的存在性,检验结果表明中国制造业大部分行业不存在"生产率悖论"。总之,文章研究认为生产率只是企业出口的一个必要条件而不是充分条件,这也重新构建了新新贸易理论的分析框架。