AN EXACT CONDITIONAL TEST FOR COVARIANCE SELECTION MODELS

An exact conditional test is developed for testing the absence of an edge in a graphical covariance selection model and is shown to be equivalent to a test based on the partial correlation coefficient. An example is given.     

Employee absence,age and tenure: A study of nonlinear effects and trivariate models

Multiple regression techniques were used to explore the nature of the relationships between age, tenure and absence in 2417 British local government workers drawn from three work groups. The data were collected from organizational records and included measures of both non-certified absence and medically certified absence. Linear and curvilinear associations among age, tenure and absence were examined. The possible moderating or mediating role of tenure in the relationship between age and absence was subsequently analysed. The data revealed linear relationships between age and absence that were negative for non-certified absence and positive for certified absence. In contrast, curvilinear relationships were found between tenure and absence that were U-shaped for noncertified absence and inverse U-shaped for certified absence. Tenure was found to moderate but not to mediate the relationship between age and absence. The implications of the results are discussed in the context of the changing age and career paths of the workforce, and of methodological issues in absence research.     

HRD in 2020: a hop-on,hop-off city tour

This article reports on the outcome of a Future Search Conference in the UK to consider human resource development (HRD) in 2020 and beyond. We firstly consider themes from the past into the present. This includes the persistence of solutions in HRD that are systematic, predictable, how apprenticeships in the UK have had to accommodate government policies to ameliorate youth unemployment and the long-standing difficulty for HRD of failing to demonstrate a return on investment (ROI) on activities. We then present four scenarios based on key questions for the future relating to value of HRD and whether this will be a future for HRD. Reponses to the questions form scenario logics which we present against the theme of city tour. Each scenario is explained against the presented logic with positive, negative, ambiguous and uncertain implications for HRD. We suggest that each scenario carries a glimpse of what might be.     

Statistical inference for olfactometer data

Summary.  Olfactometer experiments are used to determine the effect of odours on the behaviour of organisms such as insects or nematodes, and typically result in data comprising many groups of small overdispersed counts. We develop a non-homogeneous Markov chain model for data from olfactometer experiments with parasitoid wasps and discuss a relation with the Dirichlet–multinomial distribution. We consider the asymptotic relative efficiencies of three different observation schemes and give an analysis of data intended to shed light on the effect of previous experience of odours in the wasps.     

News Media and International Negotiation

It is widely recognized that leaks can hamper internationalnegotiations, but the ability of publicity to promote agreementamong nations has received less attention. This article arguesthat the press contributes to international agreement insofaras it illuminates the issues under negotiation, helps to ensureintra-governmental coordination, links governments with interestedpublics, and provides supplementary communication channels fordiplomacy.     

Adult penile circumcision: Erotosexual and cosmetic sequelae

Five men underwent circumcision in adulthood for reasons of infection, inflammation, or phimosis. Several years later, they reported on the erotosexual sequelae. All reported a prolongation of the period prior to ejaculation, though none had been genuine premature ejaculators. Other variable sequelae were diminished penile sensitivity, less penile gratification, more penile pain, and cosmetic deformity. Orgasm frequency was the same or less, and there was no postsurgical impotence. Loss of stretch receptors and reflexes might explain the major erotosexual changes. In most instances, a dorsal cut and/or antibiotic treatment achieves the same effect as circumcision, and is less risky in terms of possible pathological sequelae.     

The score function and a comparison of various adjustments of the profile likelihood

Several adjustments of the profile likelihood have the common effect of reducing the bias of the associated score function. Hence expansions for the adjusted score functions differ by a term, D_ξ, that has small asymptotic order (n ^?½). The effect of D_ξ on other quantities of interest is studied. In particular, we find the bias and variance of the adjusted maximum-likelihood estimate to be relatively unaffected, while differences in the Bartlett correction depend on D_ξ in a simple way.     

Some challenges for statistics

The paper gives a highly personal sketch of some current trends in statistical inference. After an account of the challenges that new forms of data bring, there is a brief overview of some topics in stochastic modelling. The paper then turns to sparsity, illustrated using Bayesian wavelet analysis based on a mixture model and metabolite profiling. Modern likelihood methods including higher order approximation and composite likelihood inference are then discussed, followed by some thoughts on statistical education.