Abschätzung der Varianz stetiger Merkmale aus Intervallbreite und Mittelwert

Ohne Zusammenfassung     

Polyhedral Combinatorics in Combinatorial Optimization

Polyhedral combinatorics is a subarea of combinatorial optimization of increasing practical importance. It deals with the application of the theory of linear systems and linear algebra to combinatorial problems. The paper is not intended as a survey on polyhedral combinatorics but it reviews some of the main concepts and proof techniques.     

Distribution-free tests for comparing several treatments with a control

Abstract  In this paper we propose distribution-free treatments versus control tests for the one- and two-way classifications. The null distribution properties are shown to be equivalent to those of well-known statistics for which critical values have been extensively tabled. Asymptotic relative efficiencies with respect to corresponding normal theory competitors are derived and optimal designs for the allocation of experimental units to the treatments and control are obtained.     

The occurrence of outliers in the explanatory variable considered in an errors-in-variables framework

Summary The problem of estimating the slope of a linear relationship between two jointly normally distributed random variables is considered when outliers may occur in the explanatory variable. It will be studied as a special case of an errors-in-variables problem where the explanatory variable is measured which a nonnormally distributed error. In this more general model and under certain conditions a consistent estimator can be given with a normal limiting distribution. Applications to cases of outliers in the explanatory variable will be presented.     

Effects of demographic,experiential, and attitudinal factors on occupational sex stereotypes

The purpose of this study was to (a) compare the occupational sex stereotypes of 366 college students with those reported by Shinar in 1975, and (b) examine the relationships between demographic, experiential, and attitudinal variables and these occupational sex stereotypes. The results indicated a significant difference in occupational ratings from Shinar's study, with females' perceptions shifting more than males' perceptions. In addition, subjects' gender, tenure with female managers, and attitudes toward women as managers, were shown to be significant predictors of occuptational ratings. The implications of these findings for both employees and managers are then discussed.     

Remaining life estimation of used components in consumer products: Life cycle data analysis by Weibull and artificial neural networks

Environmental awareness and legislative pressures have made manufacturers responsible for the take-back and end-of-life treatment of their products. To competitively exploit these products, one option is to incorporate used components in “new” or remanufactured products. However, this option is partly limited by a firm's ability to assess the reliability of used components. A comprehensive two-step approach is proposed. The first stage phase statistically analyzes the behavior of components for reuse. A well-known reliability assessment method, the Weibull analysis, is applied to the time-to-failure data to assess the mean life of components. In the second phase, the degradation and condition monitoring data are analyzed by developing an artificial neural network (ANN) model. The advantages of this approach over traditional approaches employing multiple regression analysis are highlighted with empirical data from a consumer product. Finally, the Weibull analysis and the ANN model are then integrated to assess the remaining useful life of components for reuse. This is a critical advance in sustainable management of supply chains since it allows for a better understanding of not only service requirements of product, but the remaining life in a product and hence its suitability for reuse or remanufacture. Future work should assess: (1) reduction in downtime of process equipment through the implementation of this technique as a means to better manage preventative maintenance; (2) reduce field failure of remanufactured product; (3) selling-service strategy through implementation of the proposed methodology.     

实验设计的新前沿

产品和过程开发是业务长期生存的基础，生存和成功的关键是培养创新和减少产品上市时间，同时使产品到达最佳性能。     

Social Welfare and Income Inequality in a System of Cities

This paper develops a general-equilibrium model of a system of core-periphery cities to examine the main determinants of intra- and inter-regional income disparities. The economy is populated by a continuum of (homogeneous) unskilled and (heterogeneous) skilled workers. Unskilled workers, whose wages are determined competitively, specialize in food production in local cities; skilled workers, whose wages are determined according to a Nash bargain, manufacture a high-tech commodity in the metropolis. We establish conditions under which this core-periphery equilibrium spatial configuration emerges. We show that both intra- and inter-regional income disparities are present; the determinants of each type of disparity and the social-welfare implications are fully investigated. Our results suggest that public policy programs that improve income equality may not be necessarily welfare enhancing.     

Pseudo empirical likelihood method in the presence of missing data

In this paper, we propose an estimator for the population mean when some observations on the study and auxiliary variables are missing from the sample. The proposed estimator is valid for any unequal probability sampling design, and is based upon the pseudo empirical likelihood method. The proposed estimator is compared with other estimators in a simulation study.     

Ecology and development

There is an increasing realization, world‐wide and in Southern Africa, that conservation and development are compatible.

Because human communities in the less developed rural areas are dependent on a renewable group of resources, including soil, water and forests, it is imperative that land use systems that protect these resources are introduced.

The predominance of subsistence agriculture in these areas is the most difficult syndrome of under‐development. An overall rural development strategy is required that integrates human development with resources management Where the population carrying capacity of the land has already been exceeded, a process of rapid villagization/urbanization is required. Village/urban growth and agricultural development require a carefully co‐ordinated programme of land capability analysis and planning, as well as active investment in infrastructure and the introduction of appropriate technologies and institutions.