Bayesian variable selection with spherically symmetric priors

We propose that Bayesian variable selection for linear parametrizations with Gaussian iid likelihoods should be based on the spherical symmetry of the diagonalized parameter space. Our r-prior results in closed forms for the evidence for four examples, including the hyper-g prior and the Zellner–Siow prior, which are shown to be special cases. Scenarios of a single-variable dispersion parameter and of fixed dispersion are studied, and asymptotic forms comparable to the traditional information criteria are derived. A simulation exercise shows that model comparison based on our r-prior gives good results comparable to or better than current model comparison schemes.     

Applying stage-gate processes to technology development—Experience from six hardware-oriented companies

The stage gate model has been proposed for application to uncertain technology development. Reports on industrial experience from such implementations are quite limited, however. This led us to explore in six companies what adaptations have been made to facilitate the model's usefulness for technology development and the companies’ experiences from their practical application of the model. Our results indicate that aspects proven important for the operational success, or failure, of the model include the level of adaptation to the characteristics of technology development and a more flexible use than that normally found in product development.     

Excluding Institutionalized Elderly from Surveys: Consequences for Income and Poverty Statistics

Growing life expectancy and changes in financial, marriage and labour markets have placed the income position of the elderly at the center of scientific and political discourse. As a consequence, the last decades witnessed the publication of various influential reports that contained comparative statistics on old age income inequalities on the basis of international surveys. Common to these surveys is that they exclude the elderly who live in institutions. The divergence between the target population (e.g. the population aged 65 and over) and the survey population (e.g. the noninstitutionalized population aged 65 and over) that thus arises, might lead to important bias in the survey results. However, hardly any research has been conducted quantifying the direction and strength of this bias. This article tries to fill this gap and assesses the consequences of excluding the institutionalized elderly for the validity and international comparability of a number of indicators. Analyses with the Belgian Datawarehouse Labour Market and Social Protection show that the resulting bias is negligible for average equivalent pension income, but that assistance dependency among pensioners is underestimated by 10%. Furthermore, on the basis of international statistics, it is shown that the share of elderly in institutions varies substantially across countries. It is argued how this jeopardizes the international comparability of old age statistics. Finally, the article opens up a discussion on the meaning of lack of income and wealth among institutionalized elderly. It concludes that depending on how this question is answered, poverty will be under- or overestimated in countries with a high share of institutionalized elderly.     

Marital Aspirations,Sexual Behaviors,and HIV/AIDS in Rural Malawi

We explore how marital aspirations are related to the sexual behaviors of adolescents and young adults in Malawi, where HIV/AIDS prevalence among adults exceeds 10%. We also consider whether the specter of AIDS is shaping ideals about marriage. By combining survey data (N = 1,087) and in‐depth interviews (N = 133) with young Malawians from the Malawi Diffusion and Ideational Change Project, we show that looking for and finding a suitable spouse are linked to sexual behaviors and, thus, HIV risks. Moreover, concerns about contracting HIV are closely tied to the ideal characteristics of a future spouse. Our findings draw long‐overdue attention to the importance of marital aspirations in understanding adolescent sexual behaviors and risks in the era of AIDS.     

Small firms and the information problem

Information is essential for decision-making and strategy by small and medium-sized enterprises. Hans Pleitner explores the content of information used by SMEs based on internal and external information and finds much deficiency. SMEs also have problems with the technicalities of handling information, although there has been a big take-up of personal computers. A lot depends on businessmen's attitudes, and these vary greatly. Dr Pleitner recommends that external institutions should try harder to encourage businessmen in the greater use of information and its technology.     

Scenarios in Europe—Who uses them and why?

The authors of this article describe a study of European companies the aim of which was to review the extent of multiple scenario analysis in company planning. They describe the differences in planning between users and non-users of the system, and analyse the benefits and drawbacks of using the system.     

Regression Analysis of Restricted Mean Survival Time Based on Pseudo-Observations

Regression models for survival data are often specified from the hazard function while classical regression analysis of quantitative outcomes focuses on the mean value (possibly after suitable transformations). Methods for regression analysis of mean survival time and the related quantity, the restricted mean survival time, are reviewed and compared to a method based on pseudo-observations. Both Monte Carlo simulations and two real data sets are studied. It is concluded that while existing methods may be superior for analysis of the mean, pseudo-observations seem well suited when the restricted mean is studied.     

Consumer Selection of Food-Safety Information Sources

The aim of this study is to examine the preferences of consumers for different information sources when they have a question about food safety. On the basis of a nationally representative survey conducted in the Netherlands, five distinct consumer groups are identified that not only differ on the reported use of information sources but also regarding several personality characteristics and sociodemographic variables. The empirical results show that two-thirds of the consumers are selective in their use of information sources and prefer either institutional or social sources. So, multiple information-acquisition patterns exist among the general public. The study illustrates how these findings can help to develop effective risk communication strategies.