Applying competing risks regression models: an overview

In many clinical research applications the time to occurrence of one event of interest, that may be obscured by another??so called competing??event, is investigated. Specific interventions can only have an effect on the endpoint they address or research questions might focus on risk factors for a certain outcome. Different approaches for the analysis of time-to-event data in the presence of competing risks were introduced in the last decades including some new methodologies, which are not yet frequently used in the analysis of competing risks data. Cause-specific hazard regression, subdistribution hazard regression, mixture models, vertical modelling and the analysis of time-to-event data based on pseudo-observations are described in this article and are applied to a dataset of a cohort study intended to establish risk stratification for cardiac death after myocardial infarction. Data analysts are encouraged to use the appropriate methods for their specific research questions by comparing different regression approaches in the competing risks setting regarding assumptions, methodology and interpretation of the results. Notes on application of the mentioned methods using the statistical software R are presented and extensions to the presented standard methods proposed in statistical literature are mentioned.     

Instrumentarien zur Vermeidung und Lösung von Gesellschafterkonflikten in Familienunternehmen

A resolution to conflicts between the participators of family businesses can hardly be achieved by implementing the common judicial methods of conflict resolution. The duplicity of the relationships between the persons involved necessitates modifications of the instruments of conflict resolution. This paper gives a review of methods suitable for avoiding and resolving conflicts between the participators of family businesses.     

Editorial

Ohne Zusammenfassung     

Two-Event Model for Carcinogenesis: Biological, Mathematical, and Statistical Considerations

A two-mutation model for carcinogenesis is reviewed. General principles in fitting the model to epidemiologic and experimental data are discussed, and some examples are given. A general solution to the model with time-dependent parameters is developed, and its use is illustrated by application to data from an experiment in which rats exposed to radon developed lung tumors.     

Diesel Engine Exhaust and Lung Cancer Mortality: Time‐Related Factors in Exposure and Risk

To develop a quantitative exposure‐response relationship between concentrations and durations of inhaled diesel engine exhaust (DEE) and increases in lung cancer risks, we examined the role of temporal factors in modifying the estimated effects of exposure to DEE on lung cancer mortality and characterized risk by mine type in the Diesel Exhaust in Miners Study (DEMS) cohort, which followed 12,315 workers through December 1997. We analyzed the data using parametric functions based on concepts of multistage carcinogenesis to directly estimate the hazard functions associated with estimated exposure to a surrogate marker of DEE, respirable elemental carbon (REC). The REC‐associated risk of lung cancer mortality in DEMS is driven by increased risk in only one of four mine types (limestone), with statistically significant heterogeneity by mine type and no significant exposure‐response relationship after removal of the limestone mine workers. Temporal factors, such as duration of exposure, play an important role in determining the risk of lung cancer mortality following exposure to REC, and the relative risk declines after exposure to REC stops. There is evidence of effect modification of risk by attained age. The modifying impact of temporal factors and effect modification by age should be addressed in any quantitative risk assessment (QRA) of DEE. Until there is a better understanding of why the risk appears to be confined to a single mine type, data from DEMS cannot reliably be used for QRA.     

近十五年西方历史学的新发展

20世纪后期,历史研究的重点继续是从分析的社会科学转移到更加强调文化因素的方面来,但是面临着迅速变化的世界局面,却具有其更加繁富且已改变了的焦点。历史学家并未受到后现代主义太多的影响,但关于应该如何重铸过去的问题的确更趋复杂了。在历史学思想与实践的重新定向过程中,人们更为深入地反思和质疑了历史作为引向今日西方文明的一种单向历程的观念,政治领域和阶级的概念扩大或改变了,妇女与性别的历史日益被纳入到通史系统中来。而在迫切需要另行考察现代性以及撰写全球史的状况面前,我们对于广泛跨文化的方法仍然缺乏综合的认知,有待于未来的进一步规划。     

Either with us or against us: experimental evidence on partial cartels

This paper analyzes the coordination challenge a partial cartel faces when payoff asymmetries between potential cartel insiders and potential cartel outsiders are large. We introduce two experimental treatments: a standard treatment where a complete cartel can be supported in a Nash equilibrium and a modified treatment where a complete cartel and a partial cartel can both be supported in a Nash equilibrium. To assess the role of communication both treatments are additionally run with a “chat option,” yielding four treatments in total. Our results show that subjects frequently reject the formation of partial cartels in the modified treatments. In all treatments with communication subjects are more likely to form complete cartels than partial cartels. The implications of these results are important for antitrust: payoff asymmetries between cartel members and outsiders may jeopardize the formation of partial cartels. Yet complete cartels may be formed instead, if institutional mechanisms with frequent communication are used to form cartels.

     

世纪之交西方史学的转折点

在20世纪的最后30年里,西方及西方以外的历史思考和历史写作方面都出现了根本性的变化。现代历史学家确信:历史是连续的、片面的过程;坚持自己科学性权利的学术研究会把来源于客观学术研究的历史叙述置于世界历史的框架之中。到了20世纪,把历史看作“人文科学”的一种特殊类型的历史研究观逐渐被把历史看作一种“社会科学”的历史观所代替。然而,对社会科学和现代化普遍持有的信心在20世纪七、八十年代受到后现代主义哲学家和文学批评家的最激烈的声讨,也受到来自历史学家,尤其是文化历史学家的较为平静的挑战,他们的论点都导致了认识论的相对论。无论如何,只有很少数的历史工作者同意后现代主义者关于“不存在客观标准”的观点,但后现代主义和文化马克思主义的某些中心思想却对日益向文化史转变的社会历史作品产生了很大影响。统一的思想或历史倾向让路给了向小单位、地方和边缘的集中关注,与之同时则是政治史研究地位的下降。在通向21世纪的世纪交替时期,我们已经看到了广泛的研究方法的多元化。