The word ‘variable’ in logic,mathematics and economics

The paper deals with the meaning of the word variable as used by various authors in various disciplines. In the first part of his article the author explains the synonyms used for this word such as indefinite numbers, mappings or concepts. He further discusses the meaning of variables and unknowns as applied in modern logic and traditional mathematics. In economic models the variable is inseparably linked to the economic quantity by which it is characterized and interpreted. Distinctions are made between endogenous and exogenous variables and between a variable and its time path.The author is indebted to Tor Fernholm for valuable comments on a preliminary draft.     

THE ROLE OF TRANSACTION COSTS FOR FINANCIAL VOLATILITY: EVIDENCE FROM THE PARIS BOURSE

This paper analyzes the causal linkage between transaction costs and financial volatility under two methodological improvements over the existing literature. First, we use panel data in which exogenous transaction cost differences in the French stock market are induced by price level dependent minimum price variation rules (tick size rules). Unlike in previous studies based on one‐time regulatory tick size changes (like the U.S. decimalization), we can separately identify and control for marketwide volatility changes. Second, we avoid the pitfalls of biased volatility measurement across regimes by using the range as a tick size robust volatility metric. Panel regressions controlling for marketwide volatility effects show at high levels of statistical significance that the hourly range volatility of individual stocks increases by more than 30% for a 20% exogenous increase in transaction costs due to tick size variations in the French trading system. In the light of this evidence, higher transaction costs in general, and security transaction taxes in particular, should be considered as volatility increasing. (JEL: F3, G1, G14)     

Hierarchie und Entlohnung

In this paper, we suggest a wage scheme that accounts for the hierarchical structure of an enterprise. We employ concepts of cooperative game theory and modify the van den Brink (2008) approach. Besides results on how the hierarchy affects wage differentials between levels of the hierarchy, we deal with the allocation of employees to the different levels.     

E-Coaching: Prozess- und Ergebnisevaluation des„Virtuellen Zielerreichungscoachings“

The authors present the design and first results of an ongoing research project. The main emphasis of the research lies on observable and mental processes of the coach and the coachee in and between coaching sessions as well as for the coachee after the coaching. The research is based on a particular e-coaching format named “virtual goal attainment coaching”, consisting of telephone-based coaching sessions combined with by internet mediated questions that the coachee answers with support of the coach. The ambition of this particular type of coaching, since based on empirical findings of coaching success factors and combined with modern media, is to generate excellent results within a short amount of time. Preliminary findings confirm the efficiency and effectiveness of this blended coaching program.     

Reconocimiento de emociones a partir de la expresión y el contexto: Una réplica

Resumen

En el presente estudio se examinan las contribuciones relativas de la expresión facial y el contexto situacional al reconocimiento de emociones. Tras la evaluación independiente de ambas fuentes de información, los sujetos juzgaron distintas combinaciones que variaban en su grado de congruencia. Aunque los resultados indican una preponderancia de la información expresiva sobre la situational en el juicio global, se señala la necesidad de nuevos diseños que permitan investigar el papel modulador del contexto sobre los juicios emocionales.     

Populations with constant immigration

We consider a Leslie‐type model of a one‐sex (female) population of natives with constant immigration. The fertility and mortality schedule of the natives may be below or above replacement level. Immigrants retain their fertility and mortality, their children adopt the fertility and mortality of the natives. It is shown how this model may be written in a homogeneous form (without additive term) with a Leslie‐type matrix. Reproductive values of individuals in each age group are discussed in terms of a left eigenvector of this matrix. The homogeneous form of our projection model permits the transformation into a Markov chain with transient and recurrent states. The Markov chain is the basis for the definition of genealogies, which incorporate immigration. It is shown that genealogies describe the life histories of individuals in a population with immigration. We calculate absorption times of the Markov chain and relate them to genealogies. This extends the theory originally designed for closed populations to populations with immigratioa     

Where are the new fathers? German families with a non-traditional distribution of professional and family work

The concepts 'new fathers' and 'new men' reflect changed attitudes about gender roles today. However, at a behavioural level, the traditional division of labour in families has proved tenacious. Wage differences between the sexes are believed to be a main reason for this. This German pilot project examined the division of labour of couples, to pursue the question of what consequences a couple's relative earnings have for a cooperative role structure as well as for the transition to parenthood. Qualitative interviews were conducted with both partners in 25 couples in which the woman's earnings were as high as or higher than those of the man. The results show clear deviations from the 'standard model', thereby indicating the significant influence of earnings. Most couples divided parental leave so that neither partner had to drop out of employment for a long period of time. The egalitarian role distribution had a positive effect on the relationship between parents and on satisfaction with this relationship. RESUMEN Los conceptos de 'padre moderno' y 'hombre nuevo' reflejan actitudes cambiadas sobre papeles de los sexos hoy en día. No obstante, al nivel de comportamiento, la división tradicional de trabajo ha sido tenaz. Se cree que esto surge principalmente de diferencias de sueldos entre los sexos. Éste proyecto piloto alemán evaluó la división de trabajo entre parejas para averiguar las consecuencias de los ingresos relativos de una pareja en la estructura cooperativa de papeles de sexo, además de el la transición a ser padres. Se llevaron a cabo entrevistas cualitativas con ambos compañeros de 25 parejas donde los ingresos de las mujeres eran iguales o superior a los del hombre. Los resultados muestran desviaciones claras del 'modelo estándar' señalando la considerable influencia de los ingresos. La mayoría de parejas compartían la baja por paternidad/maternidad para que ninguna persona tuviera que abandonar su empleo durante mucho tiempo. La distribución igualitaria de papeles afectó positivamente a la relación entre los padres y a su satisfacción con la relación.     

Repeated screening with inspection error and no false positive results with application to pharmaceutical pill production

Summary.  Repeated screening is a 100% sampling inspection of a batch of items followed by removal of the defective items and further iterations of inspection and removal. The reason for repeating the inspection is that the detection of a defective item happens with probability p <1. A missed defective item is a false negative result. The no false positive result is contemplated in this paper, which is motivated by a problem coming from the production of pharmaceutical pills. Bayesian posterior distributions for the quality of the lot are obtained for the case of both p known and p unknown. Batch rejection and batch acceptance control limits for the number of defective items at subsequent iterations can then be calculated. Theoretical connections to the problem of estimating the number-of-trials parameter of a binomial distribution are drawn.     

Evidence maps: communicating risk assessments in societal controversies: the case of engineered nanoparticles

The transparent and fair characterization of scientific evidence for reporting the results of a hazard assessment is a demanding task. In this article, we present an approach for characterizing evidence--the evidence map approach. The theoretical starting point is to view evidence characterization as a form of argumentation. Thus, evidence maps are designed to depict the evidence base, the pro and con arguments, and the remaining uncertainties, which together lead experts to their conclusions when summarizing and evaluating the scientific evidence about a potential hazard. To illustrate its use, the evidence maps approach is applied to characterizing the health-relevant effects of engineered nanoparticles. Empirical data from an online survey suggests that the use of evidence maps improves the reporting of hazard assessments. Nonexperts prefer to receive the information included in an evidence map in order to come to an informed judgment. Furthermore, the benefits and limitations of evidence maps are discussed in the light of recent literature on risk communication. Finally, the article underlines the need for further research in order to increase quality of evidence reporting.     

SKILL‐BIASED TECHNOLOGICAL CHANGE,UNEMPLOYMENT, AND BRAIN DRAIN

We develop a model of directed technology adoption, frictional unemployment, and migration to examine the effects of a change in skill endowments on the wages, employment rates, and emigration rates of skilled and unskilled workers. We find that, depending on the elasticity of substitution between skilled and unskilled workers and the elasticity of the matching function, an increase in the skill ratio can reduce both the relative unemployment rate and the relative emigration rate (brain drain) of skilled workers. We provide numerical simulations to support our findings and show that the effects are empirically relevant and potentially sizable.