Bootstrapping data with multiple levels of variation

The authors consider general estimators for the mean and variance parameters in the random effect model and in the transformation model for data with multiple levels of variation. They show that these estimators have different distributions under the two models unless all the variables have Gaussian distributions. They investigate the asymptotic properties of bootstrap procedures designed for the two models. They also report simulation results and illustrate the bootstraps using data on red spruce trees.     

Limits of quantitation for laboratory assays

Summary.  A common problem with laboratory assays is that a measurement of a substance in a test sample becomes relatively imprecise as the concentration decreases. A standard solution is to establish lower limits for reliable measurement. A quantitation limit is a level above which a measurement has sufficient precision to be reliably reported. The paper proposes a new approach to defining the limit of quantitation for the case where a linear calibration curve is used to estimate actual concentrations from measured values. The approach is based on the relative precision of the estimated concentration, using the delta method to approximate the precision. A graphical display is proposed for the assessment of estimated concentrations, as well as the overall reliability of the calibration curve. Our research is motivated by a clinical inhalation experiment. Comparisons are made between the approach proposed and two standard methods, using both real and simulated data.     

REGION, RELIGIOUS COMMITMENT, AND LIFE SATISFACTION AMONG BLACK AMERICANS

Using data from the National Survey of Black Americans (NSBA), this research examines three sets of hypotheses regarding the effects of religious commitment on life satisfaction. Further, given evidence of historical geographical differences in black culture and social structure, this study explores the regional specificity of religious influences on life satisfaction. Religious participation contributes to subjective well-being only among non-southern blacks, while private religiosity is unrelated to well-being in any analysis. There are also denominational effects: non-southern members of traditional black denominations (i.e., Baptists and Methodists) and southern Catholics report particularly high levels of life satisfaction. In addition, the effects of religion on life satisfaction are contingent upon age for non-southerners only. This study concludes with a discussion of directions for future research on religion and mental health.     

Multistage Models of Carcinogenesis: An Approximation for the Size and Number Distribution of Late-Stage Clones

Multistage models have become the basic paradigm for modeling carcinogenesis. One model, the two-stage model of carcinogenesis, is now routinely used in the analysis of cancer risks from exposure to environmental chemicals. In its most general form, this model has two states, an initiated state and a neoplastic state, which allow for growth of cells via a simple linear birth-death process. In all analyses done with this model, researchers have assumed that tumor incidence is equivalent to the formation of a single neoplastic cell and the growth kinetics in the neoplastic state have been ignored. Some researchers have discussed the impact of this assumption on their analyses, but no formal methods were available for a more rigorous application of the birth-death process. In this paper, an approximation is introduced which allows for the application of growth kinetics in the neoplastic state. The adequacy of the approximation against simulated data is evaluated and methods are developed for implementing the approximation using data on the number and size of neoplastic clones.     

A simulation of a dispatch department

The operations of the dispatch department of a manufacturing organization have been analysed in terms of matching the labour supply to the labour demand (as determined by customer orders). The problem differed somewhat from those traditionally associated with dispatch departments since set-up costs and company policy resulted in high stocks being carried. In this context, service level did not refer to the ability to supply a customer from stock, but to the proportion of orders processed within a specified time interval. The operations of the department were simulated using FINSIM—a computer simulation package developed for the BBC microcomputer. FINSIM offers the capability of seeing the simulation proceed graphically on a visual display. The final outcome of the study was an aid to decision-making consisting of a family of curves of service level against the maximum acceptable time allowed to process an order. This set of curves allowed prediction of the quantifiable consequences of any proposed changes in the department. Of particular significance was the use of the curves to help demonstrate that the seemingly important delays to order documentation within the computer department were in fact inconsequential.     

Examining the Relationship Between Female Inmate Homosexual Behavior and Attitudes Toward Homosexuality and Homosexuals

Most sociologists and penologists tend to shy away from studying inmate attitudes toward homosexuality and homosexuals. Researchers within the corrections field who focus on prison sexuality typically conduct their research on consensual samesex sexual behavior and sexual coercion. The focus of the present study, however, was to ascertain female inmates' attitudes toward homosexuality and homosexuals while exploring the role ofseveral predictor variables on their attitudes. Specifically, the authors examine the relationship between female inmate homosexual behavior and attitudes toward homosexuality and homosexuals. Because of the number of items pertaining to attitudes toward homosexuality and homosexuals, factor analysis was conducted to examine whether the items measured similar constructs. Results ofthe factor analysis revealed two distinct factors/issues:civil/personal rights and personal deviance models. The mostsalient, and only statistically significant, variables in the civil/personal rights model were age, homosexual activity prior to incarceration, and homosexual activity during incarceration. Homosexual behavior during incarceration was the only statistically significant predictor of the personal deviance model.     

Using tri-reference point theory to evaluate risk attitude and the effects of financial incentives in a gamified crowdsourcing task

Crowdsourcing has rapidly developed as a mechanism to accomplish tasks that are easy for humans to accomplish but are challenging for machines. However, unlike machines, humans need to be cajoled to perform tasks, usually through some type of incentive. Since participants from the crowd are typically anonymous and have no expectation of an ongoing work relationship with a task requester, the types of incentives offered to workers are usually short-term monetary bonuses, which have had an inconclusive impact on crowdsourcing worker quality. In this paper, we explore the notion that the risk attitude of crowdsourcing workers may play an important role in the effectiveness of incentives on task accuracy. Traditional utility theories, such as prospect theory, depend on decisions made relative to a singular reference point, whereas the tri-reference point (TRP) theory (Wang and Johnson, J Exp Psychol Gen 141:743–756, 2012) holds that three reference points impact decision making. Using the TRP theory as a guide, we develop a game that provides workers with three reference points and subsequently explores the role of multiple reference points on worker risk aversion and task accuracy.     

Sexual orientation and body weight: Evidence from multiple surveys

Previous research on sexual orientation and body weight has relied primarily on small convenience samples. I use data from two large representative public health surveys to examine the relationships between sexual orientation and body weight. First, I present new estimates of obesity rates by sexual orientation from the 2001 California Health Interview Survey (which contains information on self-reported sexual orientation) and the 1996–2002 Behavioral Risk Factor Surveillance System (which contains information on intra-household same-sex unmarried partnerships). I find evidence in both surveys that gay men are much less likely to be obese relative to their heterosexual counterparts, while lesbians are much more likely to be obese. These differences cannot be easily explained by other demographic characteristics, and there is no evidence that the differences are related to differences in physical activity or muscle strengthening activities. Moreover, I find that obese gay men are less likely to be in a partnership relative to their obese heterosexual male counterparts, even after controlling for the overall lower likelihood of partnership among gay men. This suggests that minority sexual orientation may exacerbate the barriers associated with obesity. Christopher Carpenter ia an assistant professor of Economics/Public Policy at the Graduate School of Management at the University of California at Irvine. His research focuses on health policy evaluation and the relationships between sexual orientation and economic well-being. He has recently published a methodological paper on the measurement of sexual orientation (Contemporary Economic Policy, 2004).