Comparison of causal effect estimators under exposure misclassification

Over the past decades, various principles for causal effect estimation have been proposed, all differing in terms of how they adjust for measured confounders: either via traditional regression adjustment, by adjusting for the expected exposure given those confounders (e.g., the propensity score), or by inversely weighting each subject's data by the likelihood of the observed exposure, given those confounders. When the exposure is measured with error, this raises the question whether these different estimation strategies might be differently affected and whether one of them is to be preferred for that reason. In this article, we investigate this by comparing inverse probability of treatment weighted (IPTW) estimators and doubly robust estimators for the exposure effect in linear marginal structural mean models (MSM) with G-estimators, propensity score (PS) adjusted estimators and ordinary least squares (OLS) estimators for the exposure effect in linear regression models. We find analytically that these estimators are equally affected when exposure misclassification is independent of the confounders, but not otherwise. Simulation studies reveal similar results for time-varying exposures and when the model of interest includes a logistic link.     

Vocational Psychology and Career Guidance Practice: An International Partnership

Vast changes in the world of work spurred by rapid technological growth and globalization have called for a more inclusive, progressive, and forward thinking conceptualization of vocational theory, practice, training, and policy. Discussions across 8 discussion groups at the 2007 joint symposium of the International Association for Educational and Vocational Guidance, Society for Vocational Psychology, and National Career Development Association addressed various topics in the field of vocational psychology and career guidance. Several themes emerged that have captured the attention of career scholars and practitioners across the globe: culture and context in theory and practice, research as a process within a contextual system, partnership and collaboration, and social responsibility and public policy.     

Development of a Quantitative Microbial Risk Assessment for Human Salmonellosis Through Household Consumption of Fresh Minced Pork Meat in Belgium

A quantitative microbial risk assessment (QMRA) according to the Codex Alimentarius Principles is conducted to evaluate the risk of human salmonellosis through household consumption of fresh minced pork meat in Belgium. The quantitative exposure assessment is carried out by building a modular risk model, called the METZOON-model, which covers the pork production from farm to fork. In the METZOON-model, the food production pathway is split up in six consecutive modules: (1) primary production, (2) transport and lairage, (3) slaughterhouse, (4) postprocessing, (5) distribution and storage, and (6) preparation and consumption. All the modules are developed to resemble as closely as possible the Belgian situation, making use of the available national data. Several statistical refinements and improved modeling techniques are proposed. The model produces highly realistic results. The baseline predicted number of annual salmonellosis cases is 20,513 ( SD 9061.45). The risk is estimated higher for the susceptible population (estimate  4.713 × 10⁻⁵; SD 1.466 × 10⁻⁵  ) compared to the normal population  (estimate 7.704 × 10⁻⁶; SD 5.414 × 10⁻⁶)  and is mainly due to undercooking and to a smaller extent to cross-contamination in the kitchen via cook's hands.     

European management: An emerging competitive advantage of European nations

This article extends the debate begun in the June 1992 issue of EMJ when the authors first criticized Michael Porter's explanatory framework in his Competitive Advantage of Nations (1990), over the role of national culture on the competitive advantage of nations. In this paper, Frans van den Bosch and Arno van Prooijen stress that Europe is a locus of competitive advantage if one is prepared to pay attention to the possibility of ‘European Management’ as a potential asset of European firms. In this connection, the transnationalization of European firms is of importance.     

Policy analysis in a socioeconomic model of basic needs applied to four countries

This article summarizes the results of a socioeconomic model of basic needs that was applied to four countries—Brazil, Colombia, India, and Kenya. A modeling approach was thought necessary in order to make more precise the concept of basic needs. Although the work has not been entirely successful in doing that, from the policy experiment attempted, and given the limitations of the models used, we believe that an approach centered on the provision of basic needs will help the poorest satisfy their needs more quickly than is possible under alternative approaches.     

Correlates of violent and nonviolent victimization in a sample of public high school students

This study investigates the extent to which student reports of violent and nonviolent victimization in public high schools is associated the presence of hate-related words or symbols, the availability of hard and soft drugs, and the presence of gangs. Data from the 1999 School Crime Supplement of the National Crime Victimization Survey were used for this analysis. In the final multinomial logistic regression model, the presence of hate-related words, the availability of hard drugs, and a gang presence were significantly associated with reports of violent victimization. The availability of soft drugs was significantly associated with nonviolent victimization. Findings held across gender, race/ethnicity, and urbanicity of the school's location with younger students more likely to be both violently and nonviolently victimized than older students. Implications for primary and secondary interventions aimed at school climate and the reduction of correlates of victimization are discussed.     

People for sale: the need for a multidisciplinary approach towards human trafficking

The article addresses the question of how to develop appropriate measures to tackle trafficking in women, based on the findings of a study of trafficking between the Philippines and Belgium. It argues that there is no easy or uni-dimensional solution to human trafficking, since it is influenced by a complex set of factors, often working in combination with one another. It concludes that control measures alone cannot stop the flow of trafficking in women and that a legal approach which relies solely on one type of legislation would be too narrow. An effective strategy must combine and balance punitive measures with protection of human rights, stricter border control and the removal of the root causes of irregular movements. Measures must be agreed and coordinated between origin, transit and receiving countries.     

Experiments with incentives in telephone surveys

In an effort to counter the problem of noncooperation, survey organizations are offering incentives to respondents with increasing frequency, some at the outset of the survey, as has traditionally been done in mail surveys, and some only after the person has refused, in an attempt to convert the refusal. This article reports on a series of experiments carried out over a period of about 2 years with a monthly telephone survey, the Survey of Consumer Attitudes, in an effort to increase response rates or reduce interviewer effort. We report on experiments with prepaid versus promised incentives; advance letters; and advance letters with prepaid incentives; and we also report on the effects of incentives on response quality, sample composition, response bias, interviewer and respondent expectations, and costs.