A Rank-Sum-Type Test for Paired Data with Multiple Endpoints

Clinical trials and other types of studies often examine the effects of a particular treatment or experimental condition on a number of different response variables. Although the usual approach for analysing such data is to examine each variable separately, this can increase the chance of false positive findings. Bonferroni's inequality or Hotelling's T² statistic can be employed to control the overall type I error rate, but these tests generally lack power for alternatives in which the treatment improves the outcome on most or all of the endpoints. For the comparison of independent groups, O'Brien (1984) developed a rank-sum type test that has greater power than the Bonferroni and T² procedures when one treatment is uniformly better (i.e. for all endpoints) than the other treatment(s). In this paper we adapt the rank-sum test to studies involving paired data and demonstrate that it, too, has power advantages for such alternatives. Simulation results are described, and an example from a study measuring the effects of sleep loss on glucose metabolism is presented to illustrate the methodology.     

世纪之交西方史学的转折点

在20世纪的最后30年里,西方及西方以外的历史思考和历史写作方面都出现了根本性的变化。现代历史学家确信:历史是连续的、片面的过程;坚持自己科学性权利的学术研究会把来源于客观学术研究的历史叙述置于世界历史的框架之中。到了20世纪,把历史看作“人文科学”的一种特殊类型的历史研究观逐渐被把历史看作一种“社会科学”的历史观所代替。然而,对社会科学和现代化普遍持有的信心在20世纪七、八十年代受到后现代主义哲学家和文学批评家的最激烈的声讨,也受到来自历史学家,尤其是文化历史学家的较为平静的挑战,他们的论点都导致了认识论的相对论。无论如何,只有很少数的历史工作者同意后现代主义者关于“不存在客观标准”的观点,但后现代主义和文化马克思主义的某些中心思想却对日益向文化史转变的社会历史作品产生了很大影响。统一的思想或历史倾向让路给了向小单位、地方和边缘的集中关注,与之同时则是政治史研究地位的下降。在通向21世纪的世纪交替时期,我们已经看到了广泛的研究方法的多元化。     

Bayesian palaeoclimate reconstruction

Summary.  We consider the problem of reconstructing prehistoric climates by using fossil data that have been extracted from lake sediment cores. Such reconstructions promise to provide one of the few ways to validate modern models of climate change. A hierarchical Bayesian modelling approach is presented and its use, inversely, is demonstrated in a relatively small but statistically challenging exercise: the reconstruction of prehistoric climate at Glendalough in Ireland from fossil pollen. This computationally intensive method extends current approaches by explicitly modelling uncertainty and reconstructing entire climate histories. The statistical issues that are raised relate to the use of compositional data (pollen) with covariates (climate) which are available at many modern sites but are missing for the fossil data. The compositional data arise as mixtures and the missing covariates have a temporal structure. Novel aspects of the analysis include a spatial process model for compositional data, local modelling of lattice data, the use, as a prior, of a random walk with long-tailed increments, a two-stage implementation of the Markov chain Monte Carlo approach and a fast approximate procedure for cross-validation in inverse problems. We present some details, contrasting its reconstructions with those which have been generated by a method in use in the palaeoclimatology literature. We suggest that the method provides a basis for resolving important challenging issues in palaeoclimate research. We draw attention to several challenging statistical issues that need to be overcome.     

Power of the Neyman Smooth Test for Evaluating Multivariate Forecast Densities

We compare and investigate Neyman's smooth test, its components, and the Kolmogorov-Smirnov (KS) goodness-of-fit test for testing the uniformity of multivariate forecast densities. Simulations indicate that the KS test lacks power when the forecast distributions are misspecified, especially for correlated sequences of random variables. Neyman's smooth test and its components work well in samples of size typically available, although there sometimes are size distortions. The components provide directed diagnosis regarding the kind of departure from the null. For illustration, the tests are applied to forecast densities obtained from a bivariate threshold model fitted to high-frequency financial data.     

Using a Box–Cox transformation in the analysis of longitudinal data with incomplete responses

We analyse longitudinal data on CD4 cell counts from patients who participated in clinical trials that compared two therapeutic treatments: zidovudine and didanosine. The investigators were interested in modelling the CD4 cell count as a function of treatment, age at base-line and disease stage at base-line. Serious concerns can be raised about the normality assumption of CD4 cell counts that is implicit in many methods and therefore an analysis may have to start with a transformation. Instead of assuming that we know the transformation (e.g. logarithmic) that makes the outcome normal and linearly related to the covariates, we estimate the transformation, by using maximum likelihood, within the Box–Cox family. There has been considerable work on the Box–Cox transformation for univariate regression models. Here, we discuss the Box–Cox transformation for longitudinal regression models when the outcome can be missing over time, and we also implement a maximization method for the likelihood, assumming that the missing data are missing at random.     

REGION, RELIGIOUS COMMITMENT, AND LIFE SATISFACTION AMONG BLACK AMERICANS

Using data from the National Survey of Black Americans (NSBA), this research examines three sets of hypotheses regarding the effects of religious commitment on life satisfaction. Further, given evidence of historical geographical differences in black culture and social structure, this study explores the regional specificity of religious influences on life satisfaction. Religious participation contributes to subjective well-being only among non-southern blacks, while private religiosity is unrelated to well-being in any analysis. There are also denominational effects: non-southern members of traditional black denominations (i.e., Baptists and Methodists) and southern Catholics report particularly high levels of life satisfaction. In addition, the effects of religion on life satisfaction are contingent upon age for non-southerners only. This study concludes with a discussion of directions for future research on religion and mental health.     

The Effects of Perceived Barriers,Role Models,and Acculturation on the Career Self‐Efficacy and Career Consideration of Hispanic Women

This study used path analysis to examine the relationship between perceived barriers, acculturation, and role model influence on the career self‐efficacy and career considerations of a sample of Hispanic women. Two path models were examined. The male‐dominated model accounted for 15% of the variance, and the female‐dominated model accounted for 26% of the variance. No relationship was found between the variables of interest and male‐dominated career self‐efficacy and consideration. However, perceived barriers were related to female‐dominated career consideration and Anglo acculturation significantly contributed to female‐dominated career self‐efficacy. Results are discussed with regard to career practice and research with Hispanic women.     

Mixing patterns between age groups in social networks

We present a method for estimating transmission matrices that describe the mixing and the probability of infection between age groups. Transmission matrices can be used to estimate age-dependent forces of infection in age-structured, compartmental models for the study of infectious diseases. We analyze the social network generated by the synthetic population of Portland and extract mixing patterns. Our results show that the mixing within the population consists of two groups, children and adults. Children interact most frequently with other children close to their own age, while adults interact with a wider range of age groups and the durations of typical adult contacts are shorter than typical contacts between children. Furthermore, the transmission matrix shows that children are more likely to acquire infection than adults.     

Sind Universitätsprüfungen objektiv?

In diesem Beitrag werden Ergebnisse aus einem quantitativ-historischen Forschungsprojekt vorgestellt, die es zulassen, die provokative Titelfrage nach der Objektivit?t von akademischen Prüfungen in der Zeit bis 1945 zu stellen. Die Objektivit?t wird dadurch in Frage gestellt, dass die Quoten des Nicht-Bestehens in universit?ren und nach-universit?ren Abschlussprüfungen systematisch im Zeitverlauf stiegen und fielen, und zwar im Rhythmus der Arbeitsmarktchancen der jeweiligen Karrieren, die mit dem Studienfach verbunden sind: In Zeiten von überfüllung in den Karrieren bestanden prozentual mehr Kandidaten die Prüfungen nicht. Ein m?glicher Grund sind ?nderungen des „Selektionsklimas“ im Bildungssystem. Dieser Zusammenhang k?nnte auch nach 1945 bis heute weiterbestanden haben, obwohl die bisher schlechte Datenlage hier keine generelle Aussage zul?sst.     

Suicide prevention and intervention with young people in foster care in Canada

Given the history of turmoil in their lives, foster children and young people coming into care are particularly at risk of suicide. Whether a crisis is successfully prevented, or treated and transcended, depends upon the ability of foster parents and agency staff members to understand the nature of the situation and to work together in dealing with it.