A domain outlier robust design and smooth estimation approach

Outliers that commonly occur in business sample surveys can have large impacts on domain estimates. The authors consider an outlier‐robust design and smooth estimation approach, which can be related to the so‐called “Surprise stratum” technique [Kish, “Survey Sampling,” Wiley, New York (1965)]. The sampling design utilizes a threshold sample consisting of previously observed outliers that are selected with probability one, together with stratified simple random sampling from the rest of the population. The domain predictor is an extension of the Winsorization‐based estimator proposed by Rivest and Hidiroglou [Rivest and Hidiroglou, “Outlier Treatment for Disaggregated Estimates,” in “Proceedings of the Section on Survey Research Methods,” American Statistical Association (2004), pp. 4248–4256], and is similar to the estimator for skewed populations suggested by Fuller [Fuller, Statistica Sinica 1991;1:137–158]. It makes use of a domain Winsorized sample mean plus a domain‐specific adjustment of the estimated overall mean of the excess values on top of that. The methods are studied in theory from a design‐based perspective and by simulations based on the Norwegian Research and Development Survey data. Guidelines for choosing the threshold values are provided. The Canadian Journal of Statistics 39: 147–164; 2011 © 2010 Statistical Society of Canada     

A Comparison of Affect Ratings Obtained with Ecological Momentary Assessment and the Day Reconstruction Method

Measurement of affective states in everyday life is of fundamental importance in many types of quality of life, health, and psychological research. Ecological momentary assessment (EMA) is the recognized method of choice, but the respondent burden can be high. The day reconstruction method (DRM) was developed by Kahneman and colleagues (Science, 2004, 306, 1776–1780) to assess affect, activities and time use in everyday life. We sought to validate DRM affect ratings by comparison with contemporaneous EMA ratings in a sample of 94 working women monitored over work and leisure days. Six EMA ratings of happiness, tiredness, stress, and anger/frustration were obtained over each 24 h period, and were compared with DRM ratings for the same hour, recorded retrospectively at the end of the day. Similar profiles of affect intensity were recorded with the two techniques. The between-person correlations adjusted for attenuation ranged from 0.58 (stress, working day) to 0.90 (happiness, leisure day). The strength of associations was not related to age, educational attainment, or depressed mood. We conclude that the DRM provides reasonably reliable estimates both of the intensity of affect and variations in affect over the day, so is a valuable instrument for the measurement of everyday experience in health and social research.     

Resilienz durch Training personaler Ressourcen stärken: Evaluation einer web-basierten AchtsamkeitsinterventionEnhancing resilience through training of personal resources: Evaluation of a web-based mindfulness intervention

Resilience refers to personal resources and behavioral strategies that protect psychological well-being even under high demands. The present study examines whether mindfulness fosters resilience and reduces emotional exhaustion. Furthermore, we evaluate the effectiveness of a web-based mindfulness intervention that saves costs and time compared to existing face-to-face trainings. The assumptions were tested with a sample of N = 72 employees within a pre- and posttest design with a treatment and control group. The results provide empirical evidence that mindfulness reduces emotional exhaustion, which is mediated by resilient behavior. Furthermore, the intervention is effective with regard to mindfulness.     

Estimating stage occupation probabilities in non-Markov models

We study non-Markov multistage models under dependent censoring regarding estimation of stage occupation probabilities. The individual transition and censoring mechanisms are linked together through covariate processes that affect both the transition intensities and the censoring hazard for the corresponding subjects. In order to adjust for the dependent censoring, an additive hazard regression model is applied to the censoring times, and all observed counting and “at risk” processes are subsequently given an inverse probability of censoring weighted form. We examine the bias of the Datta–Satten and Aalen–Johansen estimators of stage occupation probability, and also consider the variability of these estimators by studying their estimated standard errors and mean squared errors. Results from different simulation studies of frailty models indicate that the Datta–Satten estimator is approximately unbiased, whereas the Aalen–Johansen estimator either under- or overestimates the stage occupation probability due to the dependent nature of the censoring process. However, in our simulations, the mean squared error of the latter estimator tends to be slightly smaller than that of the former estimator. Studies on development of nephropathy among diabetics and on blood platelet recovery among bone marrow transplant patients are used as demonstrations on how the two estimation methods work in practice. Our analyses show that the Datta–Satten estimator performs well in estimating stage occupation probability, but that the censoring mechanism has to be quite selective before a deviation from the Aalen-Johansen estimator is of practical importance. N. Gunnes—Supported by a grant from the Norwegian Cancer Society.     

To move or not to move to find a new job: spatial duration time model with dynamic covariate effects

The aim of this paper is to show the flexibility and capacity of penalized spline smoothing as estimation routine for modelling duration time data. We analyse the unemployment behaviour in Germany between 2000 and 2004 using a massive database from the German Federal Employment Agency. To investigate dynamic covariate effects and differences between competing job markets depending on the distance between former and recent working place, a functional duration time model with competing risks is used. It is build upon a competing hazard function where some of the smooth covariate effects are allowed to vary with unemployment duration. The focus of our analysis is on contrasting the spatial, economic and individual covariate effects of the competing job markets and on analysing their general influence on the unemployed's re-employment probabilities. As a result of our analyses, we reveal differences concerning gender, age and education. We also discover an effect between the newly formed and the old West German states. Moreover, the spatial pattern between the considered job markets differs.     

Chemistry of growth medium and leachate from green roof systems in south-central Texas

Installation of intensive and extensive green roofs is becoming popular for reducing runoff from impervious surfaces in many cities around the world. Most studies on runoff quality from green roofs have been conducted in cooler northern climates. We examined the losses and gains of nutrients, cations and selected anions in planted and unplanted growth medium and compared these to initial growth medium (IGM) typically used for green roof modules in south-central Texas. Water extracts of growth medium and leachate from three replicates of unplanted growth medium and three planted species (Sedum kamtschaticum, Delosperma cooperi and Talinum calycinum) were examined. During the first 6 months after establishment we observed high losses of nitrate (25 to 44 mg kg⁻¹), dissolved organic carbon (DOC: 155 to 190 mg kg⁻¹) and nitrogen (DON: 9.0 to 11.2 mg kg⁻¹) and orthophosphate-P (1 to 2 mg kg⁻¹). Average leachate concentrations based on four rain events 6 months after establishment ranged from 0.3 to 6.6 mg L⁻¹ in planted modules and 6.3 mg L⁻¹ in unplanted modules for nitrate-N, 38 to 42 mg L⁻¹ in planted modules and 32 mg L⁻¹ in unplanted modules for DOC, 2.1 to 3.1 mg L⁻¹ in planted modules and 2.1 mg L⁻¹ in unplanted modules for DON and 0.27 to 0.37 mg L⁻¹ in planted modules and 0.40 mg L⁻¹ in unplanted modules for orthophosphate-P. We suggest that after the establishment of green roofs, leachate losses may contribute some runoff concentrations of nitrogen, carbon and phosphorous in urban areas.     

Gambling and problem gambling among clients,and staff attitudes,in an alcohol and drug problems treatment service in the English Midlands

A self-completion questionnaire containing items about recent gambling and problem gambling used in the British Gambling Prevalence Survey (BGPS) was completed by 274 clients of alcohol and drug problems services in the English West Midlands. Compared to BGPS data, matched to the client sample for age and sex, clients were significantly more likely in the previous 12 months to have engaged in forms of gambling carrying a high risk of problems, to have engaged in four or more separate forms of gambling, and to have scores on a brief form of the South Oaks Gambling Screen (SOGS) indicating problem gambling. A self-completion scale on attitudes towards working with problem gamblers, with good psychometric properties according to present data, was completed by 91 members of staff of the same services. With the exception of a sub-scale measuring perceived adequacy of knowledge and skills for working with problem gamblers, staff expressed moderately positive attitudes. It is concluded that British substance misuse services are appropriate locations for the development of services for problem gambling.     

Eating Disorder Symptoms Among College Students: Prevalence,Persistence, Correlates,and Treatment-Seeking

Abstract

Objective: To examine the prevalence, correlates, persistence, and treatment-seeking related to symptoms of eating disorders (EDs) in a random sample of college students. Participants: A random sample of students at a large university were recruited for an Internet survey in Fall 2005 and a follow-up survey in Fall 2007. Methods: ED symptoms were measured using the SCOFF screen and adjusted for nonresponse using administrative data and a nonresponse survey. Results: 2,822 (56%) students completed the baseline survey. Among undergraduates the prevalence of positive screens was 13.5% for women and 3.6% for men. Among students with positive screens, 20% had received past-year mental health treatment. In the follow-up sample (N = 753), ED symptoms at baseline significantly predicted symptoms 2 years later. Conclusions: Symptoms of EDs were prevalent and persistent among college students in this study. These findings suggest that brief screens can identify a large number of students with untreated EDs.