Der Hawthorne-Effekt – ein Effekt für viele Gelegenheiten?

It is shown that the concept of ?Hawthorne effect‘ was created many years after the Hawthorne studies in Western Electric Company. Presently, the ?Hawthorne effect‘ concept is increasingly used in social sciences and many other sciences. The concept is however used in different and occasionally digressive meanings. The question arises whether such a concept is useful at all. In addition, it is discussed why the rather imprecise reports of single Hawthorne field experiments have been spread as academic folklore, and why rather undefined concepts like the ?Hawthorne effect‘ are used so widely in psychology and social sciences.     

Einkommenseffekte beruflicher Weiterbildung

The claim for lifelong learning or vocational further training is most often set out without having clarified satisfactorily the individual gains which result from training activities. Based on human capital theory, which we extend by arguments from signaling- and game theory, the paper investigates for western and eastern Germany individual returns of training on income with longitudinal data (1996–1998) from the recently available “Mikrozensus-Panel”. A problem in identifying causal training effects is a selection bias caused by unobserved heterogeneity which – using conventional methods – leads to overestimation of the effects. Fixed- and Random-Effects-Models – which we discuss and confront empirically regarding the training issue – present a method for controlling the selection bias. The results show evidence for positive and significant training effects on income, although the actual amount of income growth is low. Whereas no differences by sex were found, separate analyses by age, skill levels and region indicate that not all of the subgroups benefit positively from further training activities. Therefore, the findings relativize the importance of social inequalities in the access to further training for the process of status attainment in general.     

Bisphenol A: How the Most Relevant Exposure Sources Contribute to Total Consumer Exposure

Bisphenol A (BPA) is an endocrine disrupting chemical that is found in human urine throughout industrial societies around the globe. Consumer exposure pathways to BPA include packaged food, household dust, air, and dental fillings. To date, information on the relative contribution of the different pathways to total consumer exposure is lacking, but is key for managing substance‐associated risks. We investigated the relative contributions of the pathways known to be most relevant for nine different consumer groups. Our results suggest that the most important pathways for infants and children are the use of polycarbonate (PC) baby bottles and for adults and teenagers the consumption of canned food. Dental surgery can also considerably contribute over a short time directly after the surgery. For infants fed with PC baby bottles with mean dose rates of 0.8 μg/kg_bw/d the highest exposure dose rate was calculated. This dose rate is far below the tolerable daily intake of 50 μg/kg_bw/d. However, it is of the same order of magnitude as recently reported concentrations that caused low‐dose health effects in rodents. We find a pattern of falling exposure levels with rising age that is supported by urinary concentrations of BPA available for selected consumer groups. Similarly, the exposure levels we predict are confirmed by the levels reported in these studies.     

The Determinants of Retail Productivity: A Critical Review of the Evidence

This paper discusses the literature on the established determinants of productivity in the retail sector. It also draws attention to some neglected strands of research which provide useful insights into strategies that could allow productivity enhancements in this area of the economy. To date, very few attempts have been made to integrate different specialisms in order to explain what drives productivity in retail. Here this paper rectifies this omission by putting together studies from economics, geography, knowledge management and employment studies. It is the authors’ view that quantitative studies of retail productivity should focus on total factor productivity in retailing as the result of competition/composition effects, planning regulations, information and communications technology, the multinational operation element and workforce skills. Further, the fact that retail firms possess advantages that are transferable between locations suggests that investment in strategies enhancing the transfer of explicit and tacit knowledge between and within businesses are crucial to achieve productivity gains.     

Contingencies versus External Pressure: Professionalization in Boards of Firms Affiliated to Family Business Groups in Late‐Industrializing Countries

We examine the antecedents of professionalization in boards of firms affiliated to family business groups, increasingly recognized in the literature as the dominant form of big business organization in many late‐industrializing countries. Dimensions of board professionalization that we include in our study are board size, ratio of salaried executives and outsider presence. We compare predictions on board composition derived from contingency, institutional and power perspectives. Turkish family business groups, considered as an archetypal example of this form of organization, provide the empirical setting for the study, with data on 299 firms affiliated to ten different family business groups. Our results provide greater support for institutional and power perspectives, showing that, relative to internal and external complexity facing affiliate firms, institutional pressures and the presence of joint venture partners better predict board professionalization.     

Quadratic estimation in mixed linear models with two variance components

Explicit expressions for Bayes invariant quadratic estimates, biased and unbiased, are presented and proved to cover the entire class of admissible estimates in the considered classes. An unbalanced genetic model is studied for demonstration.