Banks winners in tournaments are difficult to recognize

Given a tournament T, a Banks winner of T is the top vertex of any maximal (with respect to inclusion) transitive subtournament of T. In this technical note, we show that the problem of deciding whether some fixed vertex v is a Banks winner for T is NP-complete. Received: 22 February 2002/Accepted: 20 June 2002 Supported by the START program Y43-MAT of the Austrian Ministry of Science. I would like to thank two thank the referees for a careful reading of the paper, for helpful remarks, and for many suggestions how to improve the presentation.     

The gambling market in the Federal Republic of Germany and the helpseeking of pathological gamblers

The development of the gambling market in the Federal Republic of Germany since the middle of the seventies and data on pathological gamblers seeking help are described. The continuously increasing supply, together with increases in turnover, was followed-with some temporal delay-by an increase in the number of gamblers who sought advice and treatment. Preliminary measures taken by the health authorities as well as some consequences of pathological gambling are discussed.This article is a translation of a German article published in: Deutsche Hauptstelle gegen die Suchtgefahren (1990): Jahrbuch '91 zur Frage der Suchtgefahren. Hamburg: Neuland-Verlag.     

Self-generated fertility waves in a non-linear continuous overlapping generations model

In this paper, Samuelson's simplified version of the Easterlin theory (Samuelson 1976) is extended to a continuous-time model with three age groups. This approach enables one to apply the qualitative theory of non-linear differential equations to show the existence of Easterlin-type cycles. In contrast to the discrete time model we obtain information about the period length of the cycle.This research was supported by the Austrian Science Foundation under grant P6601.     

Coaching als Instrument zur Aufrechterhaltung der Machtstellung von Männern in Organisationen

The author discusses the question why the counseling format coaching was able to achieve such a dominant position in the market compared with other formats like supervision or organizational counseling. A point of view specific to power-and gender-related issues and the sociological concept of hegemonial masculinity (Connell) form the starting point to explore this question. Due to its origin from the field of competitive sport and based on its objective target as an instrument for human resources development (Schreyögg) the counseling format coaching serves values and role models typically attributed to men (successful, winner, potent) in an ideal way. Therefore it nourishes established models of hegemonial masculinity in organizations thus contributing to consolidate and safeguard the position of power of men, when it is used in an unreflective modality. With this in mind coaching acts in particular through segregation and as a place to reinsure masculine role models.     

(When) Is job-finding via personal contacts a meaningful concept for social network analysis? A comment to

Chua (2011) argues that in a meritocratic context, institutions restrict the usefulness of social networks in exerting influence on job seekers’ earnings. Regressing job-finding via personal contacts on earnings, he finds negative effects of influence via personal contacts, especially for the well-educated and individuals working in the state sector. In this comment, I argue that these results are ambiguous because (1) the analysis does not sufficiently distinguish between job ‘search’ methods and job ‘finding’ methods, (2) job-finding method indicates information flow rather than a personal contact's influence, and (3) it remains unclear whether Chua's analysis reflects the effect of network usage in job search per se or the effect of self-selection into network usage by individuals with low earning potential.     

Führung in Familienunternehmen: Besonderheiten der Entscheidungsfindung und Verhaltenssteuerung und deren Auswirkung auf den Unternehmenserfolg

This paper draws on a survey design to investigate whether family ownership and leadership have an influence on the decision-facilitating and decision-influencing roles of management control. Moreover, we investigate whether the more intuitive decision making in family firms which is often said to be caused by a lack of professionalism, is indeed a disadvantage. The results indicate significant differences in the use of management controls between family firms and non-family firms. However, in contrast to the prevailing view in literature, the performance of family firms is not affected negatively by their specific way of making decisions and by their more centralized management style. According to our data, the prevailing characterization of family firms as being less professionally managed seems questionable.     

Additive mixed models with approximate Dirichlet process mixtures: the EM approach

We consider additive mixed models for longitudinal data with a nonlinear time trend. As random effects distribution an approximate Dirichlet process mixture is proposed that is based on the truncated version of the stick breaking presentation of the Dirichlet process and provides a Gaussian mixture with a data driven choice of the number of mixture components. The main advantage of the specification is its ability to identify clusters of subjects with a similar random effects structure. For the estimation of the trend curve the mixed model representation of penalized splines is used. An Expectation-Maximization algorithm is given that solves the estimation problem and that exhibits advantages over Markov chain Monte Carlo approaches, which are typically used when modeling with Dirichlet processes. The method is evaluated in a simulation study and applied to theophylline data and to body mass index profiles of children.     

Latent Class Analysis of Gambling Activities in a Sample of Young Swiss Men: Association with Gambling Problems,Substance Use Outcomes,Personality Traits and Coping Strategies

The study aimed to identify different patterns of gambling activities (PGAs) and to investigate how PGAs differed in gambling problems, substance use outcomes, personality traits and coping strategies. A representative sample of 4989 young Swiss males completed a questionnaire assessing seven distinct gambling activities, gambling problems, substance use outcomes, personality traits and coping strategies. PGAs were identified using latent class analysis (LCA). Differences between PGAs in gambling and substance use outcomes, personality traits and coping strategies were tested. LCA identified six different PGAs. With regard to gambling and substance use outcomes, the three most problematic PGAs were extensive gamblers, followed by private gamblers, and electronic lottery and casino gamblers, respectively. By contrast, the three least detrimental PGAs were rare or non-gamblers, lottery only gamblers and casino gamblers. With regard to personality traits, compared with rare or non-gamblers, private and casino gamblers reported higher levels of sensation seeking. Electronic lottery and casino gamblers, private gamblers and extensive gamblers had higher levels of aggression-hostility. Extensive and casino gamblers reported higher levels of sociability, whereas casino gamblers reported lower levels of anxiety–neuroticism. Extensive gamblers used more maladaptive and less adaptive coping strategies than other groups. Results suggest that gambling is not a homogeneous activity since different types of gamblers exist according to the PGA they are engaged in. Extensive gamblers, electronic and casino gamblers and private gamblers may have the most problematic PGAs. Personality traits and coping skills may predispose individuals to PGAs associated with more or less negative outcomes.