Regenerative Markov Chain Monte Carlo for Any Distribution

While Markov chain Monte Carlo (MCMC) methods are frequently used for difficult calculations in a wide range of scientific disciplines, they suffer from a serious limitation: their samples are not independent and identically distributed. Consequently, estimates of expectations are biased if the initial value of the chain is not drawn from the target distribution. Regenerative simulation provides an elegant solution to this problem. In this article, we propose a simple regenerative MCMC algorithm to generate variates for any distribution.     

Adolescent Depression and Time Spent with Parents and Siblings

This study examines adolescent depressive symptoms and the quantity and quality of time spent by adolescents with their parents and siblings. We use measures of the quality of relationships with parents and siblings as proxy indicators for the quality of time spent with these social partners. The study emphasizes the salience of parent relationships to adolescent depression. The structural equation models suggest that time spent with parents is indirectly linked with the severity of depressive symptoms via adolescents’ perceptions of how accepting their parents are of them, and the extent to which parents avoid exerting psychological control. We discuss these findings in relation to clinical practice.     

Stakeholder Green Pressure and New Product Performance in Emerging Countries: A Cross-country Study

Despite the burgeoning literature on stakeholder green pressure, research is scarce on how it influences eco-product innovation and new product performance. This article examines stakeholder green pressures as antecedents of eco-product innovation and new product performance in firms operating in resource-constrained countries. Using data gathered from surveys in Vietnam (N = 183) and Ghana (N = 217), we find that the positive effects of stakeholder green pressures on new product performance are serially mediated by environmental sustainability orientation and eco-product innovation. Our findings contribute to ongoing efforts to clarify the mechanisms channelling stakeholder pressures into new product performance in resource-constrained environments.     

A Hybrid Geometric Phase II/III Clinical Trial Design based on Treatment Failure Time and Toxicity

The problem of comparing several experimental treatments to a standard arises frequently in medical research. Various multi-stage randomized phase II/III designs have been proposed that select one or more promising experimental treatments and compare them to the standard while controlling overall Type I and Type II error rates. This paper addresses phase II/III settings where the joint goals are to increase the average time to treatment failure and control the probability of toxicity while accounting for patient heterogeneity. We are motivated by the desire to construct a feasible design for a trial of four chemotherapy combinations for treating a family of rare pediatric brain tumors. We present a hybrid two-stage design based on two-dimensional treatment effect parameters. A targeted parameter set is constructed from elicited parameter pairs considered to be equally desirable. Bayesian regression models for failure time and the probability of toxicity as functions of treatment and prognostic covariates are used to define two-dimensional covariate-adjusted treatment effect parameter sets. Decisions at each stage of the trial are based on the ratio of posterior probabilities of the alternative and null covariate-adjusted parameter sets. Design parameters are chosen to minimize expected sample size subject to frequentist error constraints. The design is illustrated by application to the brain tumor trial.     

Does the way maternity care is provided affect maternal and neonatal outcomes for young women? A review of the research literature

BackgroundYoung pregnant women who continue a pregnancy are primarily from a socioeconomically deprived background. The risk factors associated with low socio-economic status may independently affect perinatal and neonatal morbidity to a greater extent than the young age of the woman. Young pregnant women are frequently sceptical about health care providers who they can perceive to be judgemental. This may lead to late booking for pregnancy care, attending few appointments, or not attending the health service for any antenatal care.QuestionDoes the way maternity care is provided affect maternal and neonatal outcomes for young women?MethodA systematic search of the major health databases.ResultsNine research articles met the eligibility criteria: one randomised controlled trial, three prospective cohort studies, two comparative studies with concurrent controls, two comparative studies with historical controls, and one case series.DiscussionProviding young women with a non-standard model of maternity care has some beneficial and no known detrimental effects on childbirth outcomes. While there is a dearth of evidence on the effectiveness of a Midwifery Group Practice model of care for young women, there is strong evidence to suggest that a Group Antenatal Care model increases antenatal visit attendance and breastfeeding initiation, and decreases the risk of preterm birth. There is research to indicate that a Young Women's Clinic model may also increase antenatal visit attendance and decrease the incidence of preterm birth.ConclusionMore well-designed and resourced midwifery models of care for young women should be implemented and rigorously researched.     

‘Making Pies’—A Way of Exploring Pupils’ Views on Curriculum Innovation

This article examines the use of focus groups (FGs) as a way of gathering pupils’ views on the implementation of new curricula. We provide illustrations of creative activities, which were especially designed for a case‐study research project exploring the views of 11‐year‐old pupils in English schools adopting an innovative approach to the Year 7 curriculum. We argue that combining FGs with creative methods encourages pupils to take an active role in interviews, enriches the quality of the data being collected and enhances the place of FGs as important tools in eliciting pupils’ voices for both research and curriculum planning purposes.     

Exposed Singularity

In his photographs of children in displaced persons’ camps, Salgado takes each subject seriously. His images dis‐place us through their dignity and presence. We are no longer spectators but engaged: each gaze demands a response and produces the self as exposed. Pictures of prisoners from Tuol Sleng in Cambodia take the same form: a single figure facing the camera. Here, however, we are caught in an additional and irresolvable aporia: we are faced with thousands to whom we cannot adequately respond. As Derrida argues, responsibility is only possible by sacrificing ethics: we can respond to one only by sacrificing whatever obliges us to respond to others. In the final set of images considered here, Daravuth’s positing of the indistinguishability of victim and perpetrator disturbs any easy response once more. A reading of Nancy alongside and against Derrida points to significant differences in emphasis between the two, and throws further light on the aporia of responsibility. The essay concludes that Nancy’s being singular plural is productive in emphasizing the need, politically, to focus not on how we might establish a bond between us, but rather on how it is that we seem separate at all. The photographs expose us to our inevitable engagement or being‐with.     

Toddlers Activate Lexical Semantic Knowledge in the Absence of Visual Referents: Evidence from Auditory Priming

Language learners rapidly acquire extensive semantic knowledge, but the development of this knowledge is difficult to study, in part because it is difficult to assess young children's lexical semantic representations. In our studies, we solved this problem by investigating lexical semantic knowledge in 24‐month‐olds using the Head‐turn Preference Procedure. In Experiment 1, looking times to a repeating spoken word stimulus (e.g., kitty‐kitty‐kitty) were shorter for trials preceded by a semantically related word (e.g., dog‐dog‐dog) than trials preceded by an unrelated word (e.g., juice‐juice‐juice). Experiment 2 yielded similar results using a method in which pairs of words were presented on the same trial. The studies provide evidence that young children activate of lexical semantic knowledge, and critically, that they do so in the absence of visual referents or sentence contexts. Auditory lexical priming is a promising technique for studying the development and structure of semantic knowledge in young children.