SCALE MIXTURES DISTRIBUTIONS IN STATISTICAL MODELLING

This paper presents two types of symmetric scale mixture probability distributions which include the normal, Student t, Pearson Type VII, variance gamma, exponential power, uniform power and generalized t (GT) distributions. Expressing a symmetric distribution into a scale mixture form enables efficient Bayesian Markov chain Monte Carlo (MCMC) algorithms in the implementation of complicated statistical models. Moreover, the mixing parameters, a by-product of the scale mixture representation, can be used to identify possible outliers. This paper also proposes a uniform scale mixture representation for the GT density, and demonstrates how this density representation alleviates the computational burden of the Gibbs sampler.     

Biology Matters? Intimate Relationships of Young Adults From Divorced and Intact Family Backgrounds as a Function of Biological Father and Male Model Involvement

Parental divorce generally results in reduced paternal involvement (i.e., decreased availability of a male model). The consequences are severe given the father's role in shaping children's intimate relationship beliefs and behaviors. Yet, after divorce, other sources of modeled behaviors might be available (e.g., stepfathers or grandfathers). To date, no research has compared biological paternal involvement and other male model involvement with regard to young adults' intimate relationships. Our results indicate that young adults who experience high paternal or male model involvement report more positive intimate relationship behaviors. Further, no differences were found between the high paternal involvement and high male model involvement groups, suggesting positive male model involvement might moderate the effects of divorce and low paternal involvement.     

Simultaneous Over- and Underconfidence: Evidence from Experimental Asset Markets

In this paper we investigate individual overconfidence within the context of an experimental asset market. Overall, 72 participants traded one risky asset on six markets of 12 participants each. Our results indicate that participants are not generally prone to overconfidence. A comparison of two different measures of overconfidence, (i) subjective confidence intervals and (ii) differences between objective accuracy and subjective certainty, lead to a different classification of behavior in our data-set. We observe well-calibration as well as over- and underconfidence.     

How Selective Are Real Wage Cuts? A Micro‐analysis Using Linked Employer–Employee Data

Using linked employer–employee panel data for Germany, we investigate whether firms implement real wage reductions in a selective manner. In line with insider–outsider and several strands of efficiency wage theory, we find strong evidence for selective wage cuts with high‐productivity workers being spared even when controlling for permanent differences in firms' wage policies. In contrast to some recent contributions stressing fairness considerations, we also find that wage cuts increase wage dispersion among peers rather than narrowing it. Notably, the same selectivity pattern shows up when restricting our analysis to firms covered by collective agreements or having a works council.     

Accounting for informative non‐compliance with a bivariate exponential model in the design of endpoint trials

Failure to adjust for informative non‐compliance, a common phenomenon in endpoint trials, can lead to a considerably underpowered study. However, standard methods for sample size calculation assume that non‐compliance is non‐informative. One existing method to account for informative non‐compliance, based on a two‐subpopulation model, is limited with respect to the degree of association between the risk of non‐compliance and the risk of a study endpoint that can be modelled, and with respect to the maximum allowable rates of non‐compliance and endpoints. In this paper, we introduce a new method that largely overcomes these limitations. This method is based on a model in which time to non‐compliance and time to endpoint are assumed to follow a bivariate exponential distribution. Parameters of the distribution are obtained by equating them with the study design parameters. The impact of informative non‐compliance is investigated across a wide range of conditions, and the method is illustrated by recalculating the sample size of a published clinical trial. Copyright © 2005 John Wiley & Sons, Ltd.     

Sectoral Ethos: An Investigation of the Personal Values Systems of Female and Male Managers in the Public and Private Sectors

The personal values systems of 884 public- and private-sectormanagers are compared. From that comparison inferences are drawnregarding the ethos of each sector, and potential implicationsfor managers are discussed. Although the personal-values systemsin the two sectors are quite similar, results reflect a public-sectorethos that is significantly higher in Delayed Gratificationand Self-Expansion and a private-sector ethos that is significantlyhigher in Competence, Personal Orientation, and Family Security.In addition, this study furthers the view that the personal-valuessystems of male and female managers within a given employmentsector are not significantly different.     

Teaching history in a postwar social context—the case of the Croatian Danube region

This paper discusses the results of empirical research examining history teachers’ opinions on teaching recent history, and on the revocation of a moratorium on teaching former Yugoslavia’s recent history in Serbian minority schools in the Croatian Danube region. The research was conducted in 2003, involving a sample of 29 primary and secondary history teachers in both the majority and minority programmes in the two counties affected by the moratorium. The post‐war divide is evident from the differences in teachers’ opinions regarding the moratorium’s revocation and the presentation of minority history in history teaching. On a general level however, when the history of the Croats and Serbs was not discussed, most of the teachers advocated a liberal concept of history teaching.     

Archival or perceived measures of environmental uncertainty? Conceptualization and new empirical evidence

Environmental uncertainty is a major determinant in many managerial decisions and evaluations. Yet, there is no consensus what constitutes a valid measure of uncertainty to which executives can respond. This paper explicates conceptual and methodological differences between Archival Environmental Uncertainty (AEU) and Perceived Environmental Uncertainty (PEU).     

Improvements to MCS algorithm for the maximum clique problem

In this paper we present improvements to one of the most recent and fastest branch-and-bound algorithm for the maximum clique problem—MCS algorithm by Tomita et al. (Proceedings of the 4th international conference on Algorithms and Computation, WALCOM’10, pp. 191–203, 2010). The suggested improvements include: incorporating of an efficient heuristic returning a high-quality initial solution, fast detection of clique vertices in a set of candidates, better initial colouring, and avoiding dynamic memory allocation. Our computational study shows some impressive results, mainly we have solved p_hat1000-3 benchmark instance which is intractable for MCS algorithm and got speedups of 7, 3000, and 13000 times for gen400_p0.9_55, gen400_p0.9_65, and gen400_p0.9_75 instances correspondingly.     

Letters to the Editor

Although several authors have indicated that the median test has low power in small samples, it continues to be presented in many statistical textbooks, included in a number of popular statistical software packages, and used in a variety of application areas. We present results of a power simulation study that shows that the median test has noticeably lower power, even for the double exponential distribution for which it is asymptotically most powerful, than other readily available rank tests. We suggest that the median test be “retired” from routine use and recommend alternative rank tests that have superior power over a relatively large family of symmetric distributions.