The unintended consequences of grouping in tests of asset pricing models

We identify a number of unintended consequences of grouping when the capital asset pricing model is true and when it is false. When the model is true, grouping may cause fundamental problems with the most basic capital asset pricing and cross-sectional regression relationships. For example, with traditional grouping, the market portfolio is super-efficient––unless securities in each group are value weighted. Yet, when the model is grossly false, grouping may cause the model to appear to be absolutely correct. Ironically, the only way this can occur is when securities in each group are value weighted. To make matters worse, when the model is false, the slope of a cross-sectional regression of expected returns on betas fitted to grouped data may be either steeper or flatter than when the regression is fitted to ungrouped data. In other words, grouping may exacerbate the very problem it was meant to alleviate.     

Diagnostics cannot have much power against general alternatives

Model diagnostics are shown to have little power unless alternative hypotheses can be narrowly defined. For example, the independence of observations cannot be tested against general forms of dependence. Thus, the basic assumptions in regression models cannot be inferred from the data. Equally, the proportionality assumption in proportional-hazards models is not testable. Specification error is a primary source of uncertainty in forecasting, and this uncertainty will be difficult to resolve without external calibration. Model-based causal inference is even more problematic.     

客户化供应链下顾客生命周期价值计量研究

在客户化供应链中,顾客资产对企业的生存和发展发挥着至关重要的作用,而目前缺乏对顾客生命周期价值计量的有效探讨。为此,基于客户化供应链的研究背景,在综合现有研究顾客生命周期价值不同成果的基础上获得了顾客生命周期价值计量模型,并针对该模型的不足提出了修正方案,从而获得最终的顾客生命周期价值计量模型,为提高供应链企业顾客资产管理水平,促进供应链企业顾客资产的增值提供计量依据。     

船舶应急操纵状态下人的可靠性分析方法

根据影响船员人因可靠性的因素,构建船舶应急操纵状态下人因可靠性评估指标体系;然后通过借鉴CREAM方法的分析思想,构建船舶应急操纵状态下的人员可靠性评估模型。最后,将此方法应用于某运营于国际航线的干散货船舶进行应急状态下船舶操纵人因可靠性分析,分析结果表明该方法简单易行,结果合理,很适合于当前评估船舶应急作业状态下的人因可靠性。     

An Analysis of Concepts and Evidence on the Question of Whether IFRS Should be Conservative

Do international accounting standards require conservative accounting? The IASB's conceptual framework suggests that they should not, while the research literature is largely silent on the matter, typically presuming conservatism to be an outcome of private contracting rather than standardized, public, general purpose financial reporting. In this paper, we analyze the actual requirements of IFRS. We find multiple examples of recognition requirements that lead to unconditional conservatism, measurement requirements that lead to conditional conservatism, and also presentation/disclosure requirements that further support a conservative reporting environment. These findings complement, support and deepen existing evidence in the empirical literature that accounting is in practice conservative. We show, however, that the requirements for conservatism in IFRS conflict with, first, the IASB's stated position in its conceptual framework that accounting should not be conservative and, second, the private contracting explanation for conservatism that is generally accepted in the literature. What is missing, and lies behind both conflicts, is an acknowledgement and understanding of the role of an agency/contracting perspective in enhancing the decision‐usefulness of general purpose accounting standards, given the information/incentive asymmetry and uncertainty that characterizes the real‐world context in which those standards operate. From a policy perspective, such an understanding would reconcile the IASB's conceptual framework with the actual requirements of IFRS. From a research literature perspective, such an understanding would re‐position accounting standards as central to the practice of accounting conservatism, which would in turn require revision to the generally accepted theory of a private contracting explanation for the empirical evidence of conservative accounting practice.     

Hierarchical Bayesian conjoint models incorporating measurement uncertainty

The authors explore situations where consumers supplement their judgments with a measurement of uncertainty about their own preferences, either implicitly or explicitly, and develop two sets of hierarchical Bayesian conjoint models incorporating such measurements. The first set of models uses the relative location of a rating to determine the importance or weight given to the rating, in a regression setting. The second set uses interval judgment as a dependent variable in a regression setting. After specifying the models, the authors perform a theoretical comparison with a basic Bayesian regression model. They show that, under different conditions, the proposed models will yield more precise individual-level partworth estimates. Two simulated data examples and data from a conjoint study are used to illustrate the gains that could be obtained from modeling uncertainty. In the empirical application, the authors show that model fit improves when ratings for items that respondents do not like are given more weight compared to ratings for items that they do like. Electronic Supplementary Material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

一种无人值守接力的靶场安控系统

本文论述了中国实行对外开放是邓小平和中国人民把握历史和时代发展规律作出的战略抉择并取得了巨大成就;分析总结了中国入世前对外开放的基本特征及其原因;重点探讨了中国入世后对外开放的新阶段、新特点及其应对措施,推动对外开放新阶段和开放型经济新发展。     

重量误差对隔振系统性能的影响

从如何确定航空电子设备配重模型件重量精度指标的角度,分析了重量误差对隔振系统性能的影响,提出了解决问题的观点和方法.     

POCSAG码的接收与软件译码方法

本文及时追踪世界物流产业发展中出现的第四方物流现象,论述了加入WTO后中国物流产业所面临的严峻形势——跨国公司意图垄断中国的第四方物流市场,而后提出了应对策略。     

OPTIMAL CONTINUOUS-TIME HEDGING WITH LEPTOKURTIC RETURNS

We examine the behavior of optimal mean–variance hedging strategies at high rebalancing frequencies in a model where stock prices follow a discretely sampled exponential Lévy process and one hedges a European call option to maturity. Using elementary methods we show that all the attributes of a discretely rebalanced optimal hedge, i.e., the mean value, the hedge ratio, and the expected squared hedging error, converge pointwise in the state space as the rebalancing interval goes to zero. The limiting formulae represent 1-D and 2-D generalized Fourier transforms, which can be evaluated much faster than backward recursion schemes, with the same degree of accuracy. In the special case of a compound Poisson process we demonstrate that the convergence results hold true if instead of using an infinitely divisible distribution from the outset one models log returns by multinomial approximations thereof. This result represents an important extension of Cox, Ross, and Rubinstein to markets with leptokurtic returns.