A comparison of recent nonparametric methods for testing effects in two-by-two factorial designs

The two-way two-levels crossed factorial design is a commonly used design by practitioners at the exploratory phase of industrial experiments. The F-test in the usual linear model for analysis of variance (ANOVA) is a key instrument to assess the impact of each factor and of their interactions on the response variable. However, if assumptions such as normal distribution and homoscedasticity of errors are violated, the conventional wisdom is to resort to nonparametric tests. Nonparametric methods, rank-based as well as permutation, have been a subject of recent investigations to make them effective in testing the hypotheses of interest and to improve their performance in small sample situations. In this study, we assess the performances of some nonparametric methods and, more importantly, we compare their powers. Specifically, we examine three permutation methods (Constrained Synchronized Permutations, Unconstrained Synchronized Permutations and Wald-Type Permutation Test), a rank-based method (Aligned Rank Transform) and a parametric method (ANOVA-Type Test). In the simulations, we generate datasets with different configurations of distribution of errors, variance, factor's effect and number of replicates. The objective is to elicit practical advice and guides to practitioners regarding the sensitivity of the tests in the various configurations, the conditions under which some tests cannot be used, the tradeoff between power and type I error, and the bias of the power on one main factor analysis due to the presence of effect of the other factor. A dataset from an industrial engineering experiment for thermoformed packaging production is used to illustrate the application of the various methods of analysis, taking into account the power of the test suggested by the objective of the experiment.     

Beyond Google: Bibliographic Transformation to Connect Users to Good Content

ABSTRACT

At the 2017 North Carolina Serials Conference, keynote speaker Regina Romano Reynolds—Director, U.S. ISSN Center and Head, ISSN Section at the Library of Congress—explored how bibliographic transformation can connect users to good-quality content. Offering examples of current and potential serials management projects, Reynolds shared her vision for breaking down information silos, experimenting in the resource management space, and the need for visionary leadership.     

Stressful Life Events Across the Life Span and Insecure Attachment Following Combat Trauma

Attachment orientations are mostly considered to be stable interpersonal patterns. Still, a growing body of literature shows changes in attachment orientations following stressful and traumatic events. This study examined the implications of stressful life events (SLEs) throughout the life cycle in insecure attachment orientations (anxious attachment and avoidant attachment). The sample included 664 Israeli war veterans from the 1982 Lebanon War, of whom 363 suffered from acute combat stress reaction (CSR) on the battlefield, and 301 comprised a matched control group without antecedent CSR. The findings reveal a positive correlation between insecure attachment and both acute (CSR) and chronic (post-traumatic stress disorder) stress reactions. In addition, post-war SLEs were more powerful predictors of insecure attachment than other types of SLEs. Combat exposure, as well as pre-war SLEs in childhood and adulthood, made differential contributions to both types of insecure attachment orientations. Theoretical and practical implications of these findings are discussed.     

Improving Weight of Evidence Approaches to Chemical Evaluations

Federal and other regulatory agencies often use or claim to use a weight of evidence (WoE) approach in chemical evaluation. Their approaches to the use of WoE, however, differ significantly, rely heavily on subjective professional judgment, and merit improvement. We review uses of WoE approaches in key articles in the peer‐reviewed scientific literature, and find significant variations. We find that a hypothesis‐based WoE approach, developed by Lorenz Rhomberg et al., can provide a stronger scientific basis for chemical assessment while improving transparency and preserving the appropriate scope of professional judgment. Their approach, while still evolving, relies on the explicit specification of the hypothesized basis for using the information at hand to infer the ability of an agent to cause human health impacts or, more broadly, affect other endpoints of concern. We describe and endorse such a hypothesis‐based WoE approach to chemical evaluation.     

Some Correlates of Emotional Well-Being Among New England College Students

Abstract

In a questionnaire survey of New England college students, a large number of undergraduate men and women reported problems related to their personal, social, or academic adjustment. Given a list of 22 items described as “common concerns or feelings experienced by college students,” respondents were asked to rate the extent to which each item had been a problem for them in the past year. Most students (86%) reported having very much or somewhat of a problem with one or more items on the list. Pressure to do well in school, problems with weight control, anxiety, poor concentration and depression were among the most commonly reported concerns. The prevalence of these self-reported concerns and problems was found to be significantly associated with the respondents' sex, their perceptions of their health status, and academic standing.     

Doctor/politician. Physicians often shocked by political reality

What motivates doctors to get into politics? Some say it's a broader sense of accomplishment--helping not only patients, but society as a whole. Learn how some doctor/politicians got into the game, and what they're learning as they play it.