Don't mention Stonehenge!

It rises massive and magnificent above Salisbury Plain. The extraordinary monoliths of Stonehenge leave us as impressed today as ever—and as baffled. Archaeologists argue about how it was made. Can statisticians tell the answer? Chris Jones thinks they can be of considerable assistance.     

Improved bridge constructs for stochastic differential equations

We consider the task of generating discrete-time realisations of a nonlinear multivariate diffusion process satisfying an Itô stochastic differential equation conditional on an observation taken at a fixed future time-point. Such realisations are typically termed diffusion bridges. Since, in general, no closed form expression exists for the transition densities of the process of interest, a widely adopted solution works with the Euler–Maruyama approximation, by replacing the intractable transition densities with Gaussian approximations. However, the density of the conditioned discrete-time process remains intractable, necessitating the use of computationally intensive methods such as Markov chain Monte Carlo. Designing an efficient proposal mechanism which can be applied to a noisy and partially observed system that exhibits nonlinear dynamics is a challenging problem, and is the focus of this paper. By partitioning the process into two parts, one that accounts for nonlinear dynamics in a deterministic way, and another as a residual stochastic process, we develop a class of novel constructs that bridge the residual process via a linear approximation. In addition, we adapt a recently proposed construct to a partial and noisy observation regime. We compare the performance of each new construct with a number of existing approaches, using three applications.     

Estimating a frequency distribution when the sampling is biased

A simple random sample on a random variable A allows its density to be consistently estimated, by a histogram or preferably a kernel density estimate. When the sampling is biased towards certain x-values these methods instead estimate a weighted version of the density function. This article proposes a method for estimating both the density and the sampling bias simultaneously. The technique requires two independent samples and utilises ideas from mark-recapture experiments. An estimator of the size of the sampled population also follows simply from this density estimate.     

Serials spoken here: reports of conferences,institutes, and seminars

Abstract

Reports on the Ohio Valley Group of Technical Services Librarians (OVGTSL) Annual Conference, the April 2004 New England Technical Services Librarians (NETSL) Conference, the 2004 Acquisitions Institute at Timberline Lodge, and the 2004 Conference of the North American Serials Interest Group (NASIG).

Reports are from four conferences held in various parts of the United States and cover a wide range of topics. The Ohio Valley Group of Technical Services Librarians program emphasized the relationship between technical and public services. Education, both formal and continuing, was the theme for the New England Technical Services Librarians. Timberline Lodge hosted another Acquisitions Institute featuring sessions on new discoveries. The report on the 2004 North American Serials Group Annual Conference allows Conference Student Grant Award winner Chris Brady to include some personal reflections along with summaries of the sessions he attended.     

The Effects of Corporate Elitism and Groupthink on Organizational Empathy in Crisis Situations

This study is to empirically testify that corporate elitism is an antecedent to groupthink, which prevents organizational empathy from working effectively in crises. The current study is expected to expand the boundary of crisis management literature into a company’s crisis-preparedness before a crisis occurs. The findings offer the useful guidance to organizations on how to better manage their crisis proneness through identifying the early signs of corporate elitism and groupthink.     

What does client satisfaction tell us about effectiveness?

It is common in child protection research to undertake studies of client satisfaction with services. Although these studies have their own intrinsic value, it has been argued that they tell us little if anything about effectiveness—high levels of client satisfaction mean little if child abuse continues to occur. This study, undertaken in a statutory child protection service in Australia, considers the relationship between client satisfaction and other outcome measures, including worker estimates of client progress, further notifications of abuse and whether or not children have been removed. The results show strong correlations between different measures of client satisfaction and strong correlations between different measures of worker estimates of client progress. They show weaker but statistically significant correlations between client satisfaction and worker estimates of client progress, and between client satisfaction and further notifications. There is also a significant relationship between client satisfaction and children remaining at home. However, this applies only to parents, relatives and carers, not to the primary clients themselves. It is concluded that client satisfaction studies may have value beyond simply measuring client satisfaction. However, the study also supports an argument for using more than one outcome measure if the aim is to measure effectiveness. Copyright © 2008 John Wiley & Sons, Ltd.     

Compulsive buying: Does it matter how it’s measured?

The primary purpose of the present study is to compare and contrast the validity and reliability of the Faber and O’Guinn [Faber, R. J., & O’Guinn, T. C. (1992). A clinical screener for compulsive buying. Journal of Consumer Research, 19, 459–469] and Edwards [Edwards, E. A. (1993). Development of a new scale for measuring compulsive buying behavior. Financial Counseling and Planning, 4, 67–84] compulsive buying scales within a nomological network. Although both psychometric scales were designed to measure compulsive buying, the two instruments appear to be distinct in how they conceptualize the compulsive buying phenomenon. The seven-item compulsive buying scale developed by Faber and O’Guinn (1992) is the most commonly used scale for measuring compulsive buying. The Edwards scale in contrast is not as well-known. Empirical results of the present study suggest that the two compulsive buying scales may be capturing either separate constructs, or different dimensions of the same compulsive buying construct. Edwards (1993) compulsive buying scale, for instance, is correlated with materialism but not with attitudes toward money while the Faber and O’Guinn scale is not correlated with materialism but is correlated with attitudes toward money. The present study’s results suggest, among other things, that it does in fact appear to matter how compulsive buying is measured.