An Empirical Approach to Sufficient Similarity: Combining Exposure Data and Mixtures Toxicology Data

When assessing risks posed by environmental chemical mixtures, whole mixture approaches are preferred to component approaches. When toxicological data on whole mixtures as they occur in the environment are not available, Environmental Protection Agency guidance states that toxicity data from a mixture considered “sufficiently similar” to the environmental mixture can serve as a surrogate. We propose a novel method to examine whether mixtures are sufficiently similar, when exposure data and mixture toxicity study data from at least one representative mixture are available. We define sufficient similarity using equivalence testing methodology comparing the distance between benchmark dose estimates for mixtures in both data‐rich and data‐poor cases. We construct a “similar mixtures risk indicator”(SMRI) (analogous to the hazard index) on sufficiently similar mixtures linking exposure data with mixtures toxicology data. The methods are illustrated using pyrethroid mixtures occurrence data collected in child care centers (CCC) and dose‐response data examining acute neurobehavioral effects of pyrethroid mixtures in rats. Our method shows that the mixtures from 90% of the CCCs were sufficiently similar to the dose‐response study mixture. Using exposure estimates for a hypothetical child, the 95th percentile of the (weighted) SMRI for these sufficiently similar mixtures was 0.20 (i.e., where SMRI <1, less concern; >1, more concern).     

Texting among United States young adults: An exploratory study on texting and its use within families

The current study examines general text messaging tendencies, patterns of and reasons for texting family members, and the impact of texting on familial relationships among a young U.S. adult sample. Participants were recruited through Facebook; they then completed an online questionnaire. Data from 127 young adults (men: 38; women: 87; unidentified: 2) are analyzed and compared by gender. Findings suggest that young adults text at high rates per month. Participants generally report a prompt response to texts and their ability to honestly express feelings within these messages. Results also suggest participants text family members for a variety of reasons, such as to convey information, plan activities, and engage in general conversation. Distinct gender differences, however, are evident regarding who men and women text as well as texting's effects on familial relationships. Overall, these findings expand researchers’ understanding of texting in general and its impact within the family.     

Comparing mean ranks for repeated measures data

Rank tests are considered that compare t treatments in repeated measures designs. A statistic is given that contains as special cases several that have been proposed for this problem, including one that corresponds to the randomized block ANOVA statistic applied to the rank transformed data. Another statistic is proposed, having a null distribution holding under more general conditions, that is the rank transform of the Hotelling statistic for repeated measures. A statistic of this type is also given for data that are ordered categorical rather than fully rankedo Unlike the Friedman statistic, the statistics discussed in this article utilize a single ranking of the entire sample. Power calculations for an underlying normal distribution indicate that the rank transformed ANOVA test can be substantially more powerful than the Friedman test.     

Book Reviews

Statistics for Engineering Problem Solving.: Stephen B. Vardeman. Boston, MA: PWS Publishing, 1994. 840 pp. $59.95. Reviewed by Soren Bisgaard

A Data-Based Approach to Statistics.: Ronald L. Iman. Belmont, CA: Wadsworth Publishing, 1994. xiv + 898 pp. $51.95. Reviewed by Katherine Halvorsen

Concepts in Probability and Stochastic Modeling.: James J. Higgins and Sallie Keller-McNulty. Belmont, CA: Duxbury Press, 1995. xi + 420 pp. $67.43. Reviewed by David M. Nickerson

Statistics (6th ed.).: James T. McClave and Frank H. Dietrich II. New York: Dellen/Macmillan College Publishing, 1994. xix + 967 pp. $66.00. Reviewed by Katherine Halvorsen

Data Analysis for Monitoring Human Rights.: Herbert Spirer and Louise Spirer. Washington, DC: American Association for the Advancement of Science, 1994. xiv + 126 pp. $15.00. Reviewed by Diane G. Saphire     

Do taboo trade-offs explain the difficulty in valuing health and social interventions?

Persistent anomalies in the results of willingness to pay studies, despite improvements in measurement technique, challenge the assumption in economics that all sources of value are commensurable. Two sources of incommensurability have been identified: interdimensional incommensurability, which refers to the cognitive difficulty that people encounter when trying to assign a monetary value to health; and constitutive incommensurability, which arises when some forms of trade-off are regarded as ‘taboo’. In this paper we explore whether the notion of taboo trade-offs might explain some of the difficulties experienced in health-related willingness to pay studies.     

Immigrants and Employer-provided Training

Much has been written about the labour market outcomes for immigrants in their host countries, particularly with regard to earnings, employment and occupational attainment. However, much less attention has been paid to the question of whether immigrants are as likely to receive employer-provided training relative to comparable natives. As such training should be crucial in determining the labour market success of immigrants in the long run it is a critically important question. Using data from a large-scale survey of employees in Ireland, we find that immigrants are less likely to receive training from employers, with immigrants from the New Member States of the EU experiencing a particular disadvantage. The immigrant training disadvantage arises in part from a failure on the part of immigrants to get employed by training-oriented firms. However, they also experience a training disadvantage relative to natives within firms where less training is provided.     

A fortran implementation of univariate fourier series density estimation

A set of Fortran-77 subroutines is described which compute a nonparametric density estimator expressed as a Fourier series. In addition, a subroutine is given for the estimation of a cumulative distribution. Performance measures are given based on samples from a Weibull distribution. Due to small size and modest space demands, these subroutines are easily implemented on most small computers.     

A group‐based module for adolescents to improve motivation to change sexually abusive behaviour

This article describes a group‐based intervention for adolescents specifically designed to improve motivation to change sexually abusive behaviour. The intervention is intended to be used as a single module within a comprehensive treatment programme based on cognitive behavioural and relapse prevention principles. It utilizes the Prochaska and DiClemente ( 1983 , 1986 ) model of the stages of change and Morrison's ( 1998 ) seven steps in contemplating change. We have combined these two models to produce ‘11 Steps of Motivation and Action in Changing Sexually Abusive Behaviour’. These 11 steps form the foundation of the intervention. In this paper we describe how we use the 11 steps, with accompanying illustrative vignettes and question cards describing juvenile sexual abusers at various points along the continuum of change, in order to promote the acceptance of responsibility for abusive behaviour and the development of skills to prevent reoffending. Examples of the vignettes are provided, along with a discussion of how they can be used to motivate change, develop healthy group norms in treatment and set individual goals for clients. Finally, we highlight the possibility of future applications of this intervention with male adult abusers, adolescent and adult female abusers, parents groups, significant other groups, individual clients and children with sexually aggressive behaviour. Copyright © 2001 John Wiley & Sons, Ltd.     

Book Review: Religion as a Chain of Memory. By Hervieu-Léger,Danièle. New Brunswick,NJ: Rutgers University Press, 2000. 204 pages,paperback, ISBN: 0-8135-2828-3

Qualitative Sociology -