A measure of slope-rotatability for second order response surface experimental designs

In the design of experiments for estimating the slope of a response surface, slope-rotatability is a desirable property. In this paper, a measure is introduced that enables us to assess the degree of slope-rotatability for a given response surface design. The measure takes the value zero if and only if the design is slope-rotatable, and becomes larger as the design deviates from a slope-rotatable design. Examples of applying this measure to some response surface designs are also given.     

Joint impact of multiple observations on a subset of variables in multiple linear regression

In multiple linear regression analysis, each observation affects the fitted regression equation differently and has varying influences on the regression coefficients of the different variables. Chatterjee & Hadi (1988) have proposed some measures such as DSSE_ij (Impact on Residual Sum of Squares of simultaneously omitting the ith observation and the jth variable), F_j (Partial F-test for the jth variable) and F_j(i) (Partial F-test for the jth variable omitting the ith observation) to show the joint impact and the interrelationship that exists among a variable and an observation. In this paper we have proposed more extended form of those measures DSSE_IJ, F_J and F_J(I) to deal with the interrelationships that exist among the multiple observations and a subset of variables by monitoring the effects of the simultaneous omission of multiple variables and multiple observations.     

A tobacco and alcohol use profile of San Francisco's Chinese community

Relatively little is known about Asian American tobacco and alcohol use patterns. This is particularly true of Chinese living in the United States--either U.S.-born or non-U.S.-born Chinese. This article presents data from a research project studying tobacco and alcohol use patterns in San Francisco's Chinese community. Data were secured both from focus groups and a self-report telephone survey of a random sample of 1,808 Chinese residents in San Francisco. This results indicate that the prevalence of both tobacco and alcohol use is lower for San Francisco's Chinese population than for the general population. Moreover, those persons who report smoking tend to be different from those who report consuming alcohol. The study concludes that specific, culturally relevant tobacco and alcohol prevention programs should be designed to better reach this target population.     

A method for choosing the smoothing parameter in a semi-parametric model for detecting change-points in blood flow

In a smoothing spline model with unknown change-points, the choice of the smoothing parameter strongly influences the estimation of the change-point locations and the function at the change-points. In a tumor biology example, where change-points in blood flow in response to treatment were of interest, choosing the smoothing parameter based on minimizing generalized cross-validation (GCV) gave unsatisfactory estimates of the change-points. We propose a new method, aGCV, that re-weights the residual sum of squares and generalized degrees of freedom terms from GCV. The weight is chosen to maximize the decrease in the generalized degrees of freedom as a function of the weight value, while simultaneously minimizing aGCV as a function of the smoothing parameter and the change-points. Compared with GCV, simulation studies suggest that the aGCV method yields improved estimates of the change-point and the value of the function at the change-point.     

Family Roles as Moderators of the Relationship Between Schedule Flexibility and Stress

Employer initiatives that address the spillover of work strain onto family life include flexible work schedules. This study explored the mediating role of negative work–family spillover in the relationship between schedule flexibility and employee stress and the moderating roles of gender, family workload, and single‐parent status. Data were drawn from the 2008 National Study of the Changing Workforce, a nationally representative sample of working adults (N = 2,769). The results indicated that schedule flexibility was associated with less employee stress and that these associations were mediated by perceptions of negative work–family spillover. This study found the moderating relationships of gender, family workload, and single parenting in the relationships between schedule flexibility and negative work–family spillover and stress. Schedule flexibility had stronger relationships in reducing negative work–family spillover and stress among women, single parents, and employees with heavier family workloads. The findings provide empirical support for intervention efforts involving schedule flexibility to reduce workplace stress among employees with family responsibilities.     

Structured Voluntary Youth Activities and Positive Outcomes in Adulthood: An Exploratory Study of Involvement in Scouting and Subjective Well-Being

This study explores whether youth involvement in Scouting has positive consequences later in life. We examine whether the number of years of participation in Scouting is positively associated with human and social capital and recreational lifestyles in adulthood, and whether these are linked to subjective well-being: relational, emotional, and physical health. To explore this potential relationship, we estimated a structural equation model, analyzing data from a national sample of adult males. We found that youth involvement in Scouting is positively related to subjective well-being indirectly via the positive adult outcomes.     

Bayesian estimation of rare sensitive attribute

Randomized response models have been used to estimate a population proportion of a sensitive attribute. A randomized device is typically employed to protect respondent's privacy in a survey. In addition, an unrelated question is asked to improve the statistical efficiency. In this article, we propose Bayesian estimation of rare sensitive attribute using randomized response technique, which includes a rare unrelated attribute. Two cases are considered, the proportion of a rare unrelated attribute is known and unknown. A simulation study is conducted to assess the performance of the models using mean absolute error and coverage probability. The results show that the performance depends on the parameters and is robust to priors.     

Extended scaled prediction variance optimality for modified central composite design

Robust parameter designs (RPDs) enable the experimenter to discover how to modify the design of the product to minimize the effect due to variation from noise sources. The aim of this article is to show how this amount of work can be reduced under modified central composite design (MCCD). We propose a measure of extended scaled prediction variance (ESPV) for evaluation of RPDs on MCCD. Using these measures, we show that we can check the error or bias associated with estimating the model parameters and suggest the values of α recommended for MCCS under minimum ESPV.