On pseudo-values for regression analysis in competing risks models

For regression on state and transition probabilities in multi-state models Andersen et al. (Biometrika 90:15–27, 2003) propose a technique based on jackknife pseudo-values. In this article we analyze the pseudo-values suggested for competing risks models and prove some conjectures regarding their asymptotics (Klein and Andersen, Biometrics 61:223–229, 2005). The key is a second order von Mises expansion of the Aalen-Johansen estimator which yields an appropriate representation of the pseudo-values. The method is illustrated with data from a clinical study on total joint replacement. In the application we consider for comparison the estimates obtained with the Fine and Gray approach (J Am Stat Assoc 94:496–509, 1999) and also time-dependent solutions of pseudo-value regression equations.     

Nonparametric density deconvolution by weighted kernel estimators

Nonparametric density estimation in the presence of measurement error is considered. The usual kernel deconvolution estimator seeks to account for the contamination in the data by employing a modified kernel. In this paper a new approach based on a weighted kernel density estimator is proposed. Theoretical motivation is provided by the existence of a weight vector that perfectly counteracts the bias in density estimation without generating an excessive increase in variance. In practice a data driven method of weight selection is required. Our strategy is to minimize the discrepancy between a standard kernel estimate from the contaminated data on the one hand, and the convolution of the weighted deconvolution estimate with the measurement error density on the other hand. We consider a direct implementation of this approach, in which the weights are optimized subject to sum and non-negativity constraints, and a regularized version in which the objective function includes a ridge-type penalty. Numerical tests suggest that the weighted kernel estimation can lead to tangible improvements in performance over the usual kernel deconvolution estimator. Furthermore, weighted kernel estimates are free from the problem of negative estimation in the tails that can occur when using modified kernels. The weighted kernel approach generalizes to the case of multivariate deconvolution density estimation in a very straightforward manner.     

Net migration and migration effectiveness: A comparison between Australia and the United Kingdom, 1976–96

This paper explores the impact of net migration in Australia and the United Kingdom using measures of migration effectiveness computed from period-age migration data for four consecutive five-year periods. Results reported in Part 1 of this paper (Stillwellet al. 2000) suggest that while the overall effectiveness of net migration at the scale of city regions has declined over the twenty-year period in both countries, important geographical variations are evident. Part 2 considers how patterns of migration effectiveness vary by age and presents a single classification of all the city regions on the basis of age-specific effectiveness. More detailed analysis includes spatial patterns for particular age groups and net migration profiles of selected regions. Cohort effects are shown to be important for explaining changes between time periods in these regions.     

Sustained Empathic Focus and its Application in the Treatment of Couples

Although all psychoanalytically informed approaches to couples therapy recognize the importance of underlying dynamics, there are important differences in the focus of the treatment. This paper suggests a focus that is based on a self-psychological/intersubjective viewpoint. Two concepts that exemplify this model, a sustained empathic focus and an appreciation of the experience of vulnerability, are discussed and applied to a couples session. What is emphasized in this material is a process of focusing on underlying vulnerability, affect and subjective experience.

How Sunday, price, and social norms influence donation behaviour

We describe a natural field experiment investigating donation behaviour. The setting was an art gallery where donations could be deposited into a transparent box in the foyer. Two aspects of the donation environment were manipulated: signs on the donation box and the initial contents of the box. We used three sign treatments: a control with no sign, a sign that thanked donors, and a sign that indicated donations would be matched. We used two initial contents treatments: one with relatively little money ($50) and one with four times as much. The average donation per donor was significantly larger in the $200 treatments but this was offset by a decrease in the propensity to donate. In the matching treatments donations were significantly larger both at the per donor and per visitor level. A control variable turned out to have the largest influence on donation behaviour: the day of the week. The average donation per visitor was 51% higher on Sundays, when compared to every other day of the week.     

Ground beetle (Coleoptera: Carabidae) communities on green roofs in Switzerland: synthesis and perspectives

Urban Ecosystems - Green roofs have recently gained recognition for their potential contribution to urban ecosystems by providing, among other services, habitat for plants and animals, and stepping...