A class of distribution-free control charts

Summary.  A class of Shewhart-type distribution-free control charts is considered. A key advantage of these charts is that the in-control run length distribution is the same for all continuous process distributions. Exact expressions for the run length distribution and the average run length (ARL) are derived and properties of the charts are studied via evaluations of the run length distribution probabilities and the ARL. Tables are provided for implementation for some typical ARL values and false alarm rates. The charts proposed are preferable from a robustness point of view, have attractive ARL properties and would be particularly useful in situations where one uses a classical Shewhart   X -chart. A numerical illustration is given.     

Recurrent events analysis in the presence of time-dependent covariates and dependent censoring

Summary.  Recurrent events models have had considerable attention recently. The majority of approaches show the consistency of parameter estimates under the assumption that censoring is independent of the recurrent events process of interest conditional on the covariates that are included in the model. We provide an overview of available recurrent events analysis methods and present an inverse probability of censoring weighted estimator for the regression parameters in the Andersen–Gill model that is commonly used for recurrent event analysis. This estimator remains consistent under informative censoring if the censoring mechanism is estimated consistently, and it generally improves on the naïve estimator for the Andersen–Gill model in the case of independent censoring. We illustrate the bias of ad hoc estimators in the presence of informative censoring with a simulation study and provide a data analysis of recurrent lung exacerbations in cystic fibrosis patients when some patients are lost to follow-up.     

Random change point models: investigating cognitive decline in the presence of missing data

With the aim of identifying the age of onset of change in the rate of cognitive decline while accounting for the missing observations, we considered a selection modelling framework. A random change point model was fitted to data from a population-based longitudinal study of ageing (the Cambridge City over 75 Cohort Study) to model the longitudinal process. A missing at random mechanism was modelled using logistic regression. Random effects such as initial cognitive status, rate of decline before and after the change point, and the age of onset of change in rate of decline were estimated after adjustment for risk factors for cognitive decline. Among other possible predictors, the last observed cognitive score was used to adjust the probability of death and dropout. Individuals who experienced less variability in their cognitive scores experienced a change in their rate of decline at older ages than individuals whose cognitive scores varied more.     

Raising Societal Support for Development Cooperation: The Role of Students’ Exchange Programs

This article analyzes the development education and exchange activities of the Dutch development organization Edukans with its longstanding experience in the “Going Global” program among secondary schools in The Netherlands. Based on a survey with 186 direct participants in the foreign exchange program and 608 schoolmates at 126 secondary schools, a detailed analysis is made of differences in knowledge, attitudes, and behavior with respect to international cooperation, and tolerance regarding ethnic minorities. To guarantee unbiased impact assessment, the same data is collected among 276 students of a comparison group. Propensity score-matching techniques are used for data analysis, controlling for intrinsic differences among the three groups. Results show that international exchange programs have a significant positive impact on all four dimensions of societal support of the direct participants compared to their schoolmates. Only knowledge and attitudes changes are registered in the scores of the schoolmates compared to the comparison group. These outcomes remain robust when corrected for individual and school characteristics, parental background, and political preferences, and when unobserved heterogeneity is included.     

Ryff’s Six-factor Model of Psychological Well-being, A Spanish Exploration

This article aims to provide researchers interested in using Ryff’s Scales of Psychological Wellbeing with additional information to make an informed decision on the scales and items to use. It builds on the discussion in the literature on the six factor structure of this measure. An alternative shortened version of this wellbeing measure (Van Dierendonck 2004). Personality and Individual Differences, 36, 629–643) was analyzed in a combined Spanish language sample from Spain and Columbia. Using confirmatory factor analysis, one-, two-, three- and six-factor models were compared. The results showed that indeed four out the six dimensions overlapped considerably. Nevertheless, the model that fit the data best was the six factor model with one underlying second order well-being factor, hereby confirming Ryff’s model in a non-Anglo–Saxon culture.     

争取食品权的国际人权

在人权中具体讨论人类有关食品的权利有利于促进了人权理论在学术界的发展(Craven,1995年,第110-114页)。对此,本篇论文首先介绍了有关人权法学理论的一般发展状况,并在此基础上重点强调了食品权利的发展以及两者之间的相互作用。此外,人权发展不仅体现出国际特色、国家特色,也因为欧盟这些区域组织的作用而颇具区域特色,为此本文也论述了欧盟对于人权和食品权的落实和保障情况。     

Measuring changes in consumer confidence

Consumer confidence indicators are surveyed monthly and each month concern different individuals. This complicates a straightforward interpretation of shifts in confidence. First, it is not clear how many respondents switch from and to negative, neutral and positive opinions in consecutive months. Second, reported net changes in confidence may be largely driven by the different respondent samples used over time. The proposed methodology addresses both issues. It involves estimating unobserved switching between negative, neutral and positive opinions for what can be thought of as being the same set of individuals. Next, a new change-in-confidence measure is developed from these switching proportions and the associated confidence bounds are computed for testing purposes. Applications to US and Dutch confidence data show that US respondents tend to switch attitudes more often than their Dutch counterparts do. Furthermore, the illustrations show that monthly changes in consumer confidence are not often significantly different from zero. Hence, claims about increased or decreased confidence should be made with care.     

Theories of network exchange: Anomalies,desirable properties,and critical networks

The present study evaluates four well-known theories of exchange in networks. In previous research these theories’ predictions were compared for a small set of networks using experimental data. We compared their predictions for all 12,112 networks up to size 8. By comparing these predictions we (i) identified anomalies in theories of network exchange, (ii) investigated to what extent the theories satisfy basic principles of exchange, (iii) identified ‘critical’ networks for which predictions are very different. We conclude that exchange in networks is not yet well understood.