The problem of optimum stratification and allocation withq=n/N>0

Summary Dalenius/Gurney [1951] published necessary conditions for the stratum boundaries, so that with Neyman's optimal allocation of the sample sizen the variance of the sample mean will become a minimum. They introduced in the variance of the sample mean for the sample sizesn _h the opti mal values according to Neyman and differentiated this variance with respect to the stratum boundaries. Because Neyman's allocation formula yields only feasible solutions forn _h N _h , the conditions ofDalenius result in wrong, i.e. nonfeasible solutions, if one of the restrictionsn _h N _h (h=1 (1) L) is violated.By the example of a logarithmic normal distribution with =0, =1,5 forL=2 the behaviour of the Dalenius-Neyman-minimum and that of the feasible minimum will be shown in dependence on the sampling fractionq=n/N and a critical valueq _c will be given. For valuesq>q _c the Dalenius-Neyman-minimum is no longer feasible.For the same logarithmic normal distribution andL=2 (1) 10 this critical sampling fractionq _c will be given (section 5).For different values of andq the optimal stratum boundaries and sampling fractions are listed in section 6 forL=2;3;4.     

Einkommen,Preise und Wechselkurs

Ohne ZusammenfassungIch danke Prof. Klaus Rose, Prof. Helga Luckenbach und Prof. Otmar Issing für freundliche Anregungen.     

Interaktivität, Interaktion, Internet

In recent years, numerous suggestions have been made to clarify the concept of interactivity in communication science. Most often, an inclusion strategy is used, in which diverse definitions are summarized into a multi-dimensional notion of interactivity. Aside from this, there is also an exclusion strategy: On the one hand, certain technical media (computer-mediated communication, »interactive television«) or communicative situations (face-to-face communication) are marked as »interactive«. In doing this, no differentiation is made between potential and process, and betwen »interactivity« and »interaction«. On the other hand, the notion of interaction as it is rooted in sociology offers itself for a theoretically grounded definition. Seven ways of using the term in relationsship to the notion of communication can be found. It is suggested to conceptualize interaction as a type of communication in the sense of Rafaeli: Interactive communication is reciprocal and relates to earlier messages. The concept of interactive communication chosen here can be linked with systems theory and the deliberative theory of the public sphere.     

Änderungen der durchschnittlichen Blutdruckwerte in den Jahren 1956–1968

Ohne Zusammenfassung     

Book reviews

Abstract

This article examines the cultural field of fitness as a network of producers, consumers, products and practices that has developed around the care of the body through physical exercise. Drawing on a thematic text analysis of US exercise manuals, the paper focuses on how the commercial fitness field naturalizes associations between physical exercise and leisure, and between leisure and self‐work. In particular, the analysis examines three themes and their relevance to our broader understanding of leisure in contemporary consumer society: the management of leisure time; the use of leisure for self‐investment strategies; and the promotion of consumption as the framework for leisure and an accompanying notion of pleasure. The fitness field casts light on how leisure more generally is constructed as a sphere of obligations to make productive use of one’s time, to improve one’s body and self, and to do so through the wares of the consumer marketplace. The cultural imaginary of leisure as a time of freedom from work and responsibility is thus recast, in an age of individualization, as a time of freedom to accomplish the work of self‐production.