Statistical consulting

The paper and the special issue focus on the activity of statistical consulting and its varieties. This includes academic consulting, consulting to and in industry as well as statistics in public media.     

Predicting body fat using weight–height indices

While body fat is the most accurate measure of obesity, its measurement requires special equipment that can be costly and time consuming to operate. Attention has thus typically focused on the easier to calculate body mass index (BMI). However, the ability of BMI to accurately identify obesity has been increasingly questioned. This paper focuses attention on whether more general body mass indices are appropriate measures of body fat. Using a data set of body fat, height, and weight measurements, general models are estimated which nest a wide variety of weight–height indices as special cases. In the absence of a race and gender categorisation, the conventional BMI was found to be the appropriate index with which to predict body fat. When such a categorisation was made, however, the BMI was never selected as the appropriate index. In general, predicted female body fat was some 10 kg higher than that of a male of identical build and predicted % body fat was over 11 percentage points higher, but age effects were smaller for females. Considerable racial differences in predicted body fat were found for males, but such differences were less marked for females. The implications of this finding for interpreting recent research on the effect of obesity on health, society, and economic factors are considered.     

Optimal scaling of Metropolis algorithms: Heading toward general target distributions

The authors provide an overview of optimal scaling results for the Metropolis algorithm with Gaussian proposal distribution. They address in more depth the case of high‐dimensional target distributions formed of independent, but not identically distributed components. They attempt to give an intuitive explanation as to why the well‐known optimal acceptance rate of 0.234 is not always suitable. They show how to find the asymptotically optimal acceptance rate when needed, and they explain why it is sometimes necessary to turn to inhomogeneous proposal distributions. Their results are illustrated with a simple example.     

Estimating the distribution function using k-tuple ranked set samples

The basic assumption underlying the concept of ranked set sampling is that actual measurement of units is expensive, whereas ranking is cheap. This may not be true in reality in certain cases where ranking may be moderately expensive. In such situations, based on total cost considerations, k-tuple ranked set sampling is known to be a viable alternative, where one selects k units (instead of one) from each ranked set. In this article, we consider estimation of the distribution function based on k-tuple ranked set samples when the cost of selecting and ranking units is not ignorable. We investigate estimation both in the balanced and unbalanced data case. Properties of the estimation procedure in the presence of ranking error are also investigated. Results of simulation studies as well as an application to a real data set are presented to illustrate some of the theoretical findings.     

The Development of Affect Specificity in Infants' Use of Emotion Cues

This study examined the emergence of affect specificity in infancy. In this study, infants received verbal and facial signals of 2 different, negatively valenced emotions (fear and sadness) as well as neutral affect via a television monitor to determine if they could make qualitative distinctions among emotions of the same valence. Twenty 12‐ to 14‐month‐olds and 20 16‐ to 18‐month‐olds were examined. Results suggested that younger infants showed no evidence of referential specificity, as they responded similarly to both the target and distracter toys, and showed no evidence of affect specificity, showing no difference in play between affect conditions. Older infants, in contrast, showed evidence both of referential and affect specificity. With respect to affect specificity, 16‐ to 18‐month‐olds touched the target toy less in the fear condition than in the sad condition and showed a larger proportion of negative facial expressions in the sad condition versus the fear condition. These findings suggest a developmental emergence after 15 months of age for affect specificity in relating emotional messages to objects.     

The Classed Body in the Sociological Imagination

Class theorists of embodiment in Sociology point to and illuminate both an over‐ and an under‐exposed body and experience that ultimately mark the bodies of the poor as ideologically, discursively and materially abject. In this essay, I map out theories of the bodies of the poor, including those of Marx, Engels, Elias, Bourdieu, Foucault, Donzelot and Adair. I suggest that an understanding of the ways in which the bodies of the poor are positioned as abject can facilitate a flexible and reflexive heuristic through which we can negotiate epistemic shifts between material and discursive categories, as well as providing us with a template through which we can come to understand even the most profoundly abject bodies, those of poor women in a welfare state, as potential sites of embodied agency and resistance, all central to the ethical and holistic study of sociology.     

Some results on optimality in models with heteroscedastic errors from partial optimum designs

This paper studies optimum designs for linear models when the errors are heteroscedastic. Sufficient conditions are given in order to obtainD-, A- andE-optimum designs for a complete regression model from partial optimum designs for some sub-parameters. A result about optimality for a complete model from the optimality for the submodels is included. Supported by Junta de Andalucía, research group FQM244.     

The Impact of Maternal Characteristics and Sensitivity on the Concordance Between Maternal Reports and Laboratory Observations of Infant Negative Emotionality

The moderating role of maternal characteristics and maternal sensitivity on the concordance between maternal reports and laboratory observations of negative emotionality was examined. Participants were 90 primiparous mothers and their infants. Mothers completed questionnaires about remembered care from their own parents and their depressive symptoms prenatally, infant temperament (distress to novelty and distress to limitations), and depressive symptoms postnatally. Mothers and infants participated in a laboratory assessment of infant temperament (distress to novelty and limitations) and maternal sensitivity at 6 months postpartum. Several factors that moderate the degree of concordance between maternal reports and behavioral observations were identified, as predicted. Novelty concordance was higher when mothers reported having their emotional needs met in childhood and low prenatal depressive symptoms. Limitations concordance was higher when mothers were less sensitive during the observational tasks. Methodological and theoretical implications are discussed.