A pattern-mixture odds ratio model for incomplete categorical data

Most models for incomplete data are formulated within the selection model framework. Pattern-mixture models are increasingly seen as a viable alternative, both from an interpretational as well as from a computational point of view (Little 1993, Hogan and Laird 1997, Ekholm and Skinner 1998). Whereas most applications are either for continuous normally distributed data or for simplified categorical settings such as contingency tables, we show how a multivariate odds ratio model (Molenberghs and Lesaffre 1994, 1998) can be used to fit pattern-mixture models to repeated binary outcomes with continuous covariates. Apart from point estimation, useful methods for interval estimation are presented and data from a clinical study are analyzed to illustrate the methods.     

“现代化”之后的东亚农业和农村社会——日本、韩国和台湾地区的案例及其历史意蕴

日本、韩国和台湾地区的农业和农村通常被看作中国大陆农业和农村的样板。但是,以粮食大量依赖进口,农村的空洞化、老龄化和劳动力不足,以及与"新娘短缺"相伴的"外籍新娘"的涌入为代表,这三个国家和地区的粮食和人口的再生产都处于难以持续的状态,"现代化"之后的农业和农村实际上都处于严重的危机之中。这种状况与其具有高度竞争力的工业和拥挤的城市形成鲜明对照,它是"东亚模式"或"东亚资本主义"的一种必然结局,也对中国大陆农业和农村的未来演变趋势提出了警示。     

Analysis of a continuous-time proportional hazard model using discrete duration data

Many economic duration variables are often available only up to intervals, and not up to exact points. However, continuous time duration models are conceptually superior to discrete ones. Hence, in duration analyses, one faces a situation with discrete data and a continuous model. This paper discusses (i) the asymptotic bias of a conventional approximation procedure in which a discrete duration is treated as an exact observation; and (ii) the efficiency of a correct maximum likelihood estimator which appropriately accounts for the discrete nature of the data.     

Robust methods in econometrics

This survey of recent developments in robust estimation and inference is directed primarily toward econometricians. It is argued that many of the techniques in common use in econometrics are highly sensitive to unverified hypotheses. Recent progress in designing alternative robust procedures is described and some prospects for future developments are discussed.     

Predicting the Condom Assertiveness of Collegiate Females in the United States From the Expanded Health Belief Model

ABSTRACT. Collegiate females in the United States are susceptible to sexually transmitted infections (STIs) due to their propensity for sexual exploration, multiple sexual partnerships, and inconsistent safe-sex practices. Despite the potential for safe-sex communication to contribute to safer sex, little is known about the predictors of this form of sexual communication. Research on condom assertiveness—the unambiguous messaging that sex without a condom is unacceptable—is especially rare. This study employed the Expanded Health Belief Model (EHBM) in an attempt to understand why some collegiate females are more condom assertive than others. Compared with less condom-assertive females, more condom-assertive females have more faith in the effectiveness of condoms, believe more in their own condom communication skills, perceive that they are more susceptible to STIs, believe there are more relational benefits to being condom assertive, believe their peers are more condom assertive, and intend to be more condom assertive. Overall, EHBM variables accounted for nearly 70% of the variability in condom assertiveness. Several of these associations, however, were moderated by sexual compulsivity and general assertiveness. Implications of these findings for sexual health practitioners are discussed, and directions for future research are suggested.     

Decentralized WIP-oriented manufacturing control (DEWIP)

DEWIP is a manufacturing control system for job shop environments aiming at achieving short and reliable lead times by establishing WIP control loops between the manufacturing work centres. The paper describes the mode of function, the setting of parameters and simulation results of the new manufacturing control system. The setting of parameters is done with the aid of the funnel model and the theory of logistic operating curves, both developed at the Institute of Production Systems at the University of Hanover. The simulation is conducted using industrial data and makes it possible to assess DEWIP with regard to lead times, WIP level, performance and schedule reliability. DEWIP is compared both with an uncontrolled process and with the manufacturing control systems Load oriented order release (LOOR), Conwip and Polca. The results suggest that DEWIP and the models employed for the setting of parameters are suitable for job shop production and therefore offer a valuable alternative to prevailing centralized manufacturing control systems.     

Applying stage-gate processes to technology development—Experience from six hardware-oriented companies

The stage gate model has been proposed for application to uncertain technology development. Reports on industrial experience from such implementations are quite limited, however. This led us to explore in six companies what adaptations have been made to facilitate the model's usefulness for technology development and the companies’ experiences from their practical application of the model. Our results indicate that aspects proven important for the operational success, or failure, of the model include the level of adaptation to the characteristics of technology development and a more flexible use than that normally found in product development.     

基于贝叶斯图模型方法的投资组合决策

提出基于贝叶斯思想的图模型结构检测方法:首先给出精度矩阵新的参数化方法,且通过MCMC方法给出算法设计,最后将该图模型方法应用于中国证券市场,研究在牛市和熊市下证券市场六大板块之间的条件相关性.实证结果表明:牛市和熊市下的行业板块图结构存在显著差异,熊市似乎有着更强的相关性.     

集团公司战略风险管理的理论探讨

本文对集团公司战略管理过程中产生战略风险的机制从公司整体运行的角度进行研究,提出了公司战略风险管理的系统化理论模型,并从公司的环境、资源、能力和公司主题战略四个方面分析了战略风险产生的风险机理。并提出了环境和资源对公司战略主题目标的实现的影响及产生风险的机制。     

现代企业竞争及竞争效能描述新探

现代企业竞争已不再是传统竞争观念之下的企业之间为争夺最终消费者而展开的市场竞争了。现代企业要想在竞争中建立优势,就必须全面关注一切可能影响企业竞争力的相关组织和个人的作用。本文采用定性分析和定量分析相结合的方法,对现代企业竞争及其效能描述提出了一种全新的观点。