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.     

Alles ist gut

All is good — wisdom’s use in managementIn crisis periods the demand for orientation knowledge grows. Everybody is looking for the answers to the fundamental questions of life. For over 2000 years philosophy has such a knowledge: wisdom. But what is wisdom and what is its use for the management? On this question the essay with Kant gives the answer: Wisdom is the way of self-knowledge. And self-knowledge is the very source of each vision, without which there is no successful entrepreneurship.     

Führung — der unterschätzte Beruf

Leadership — an underestimated profession. From a greenhorn of leadership to a qualified manager The author presents an empirical inquiery, basing on interviews with 10 recently appointed managers. She demontrates, that managers hardly ever are prepared for her job in advance. This may lead to several problems, up to a demotivation of all persons envolved. The author proposes a procedure of personal development with three elements: seminars to impart knowledge, employment of internal mentors and of external coaches.     

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.     

Is Poker a Game of Skill or Chance? A Quasi-Experimental Study

Due to intensive marketing and the rapid growth of online gambling, poker currently enjoys great popularity among large sections of the population. Although poker is legally a game of chance in most countries, some (particularly operators of private poker web sites) argue that it should be regarded as a game of skill or sport because the outcome of the game primarily depends on individual aptitude and skill. The available findings indicate that skill plays a meaningful role; however, serious methodological weaknesses and the absence of reliable information regarding the relative importance of chance and skill considerably limit the validity of extant research. Adopting a quasi-experimental approach, the present study examined the extent to which the influence of poker playing skill was more important than card distribution. Three average players and three experts sat down at a six-player table and played 60 computer-based hands of the poker variant “Texas Hold’em” for money. In each hand, one of the average players and one expert received (a) better-than-average cards (winner’s box), (b) average cards (neutral box) and (c) worse-than-average cards (loser’s box). The standardized manipulation of the card distribution controlled the factor of chance to determine differences in performance between the average and expert groups. Overall, 150 individuals participated in a “fixed-limit” game variant, and 150 individuals participated in a “no-limit” game variant. ANOVA results showed that experts did not outperform average players in terms of final cash balance. Rather, card distribution was the decisive factor for successful poker playing. However, expert players were better able to minimize losses when confronted with disadvantageous conditions (i.e., worse-than-average cards). No significant differences were observed between the game variants. Furthermore, supplementary analyses confirm differential game-related actions dependent on the card distribution, player status, and game variant. In conclusion, the study findings indicate that poker should be regarded as a game of chance, at least under certain basic conditions, and suggest new directions for further research.     

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.