Horwitz's rule, transforming both sides and the design of experiments for mechanistic models

Summary. The paper develops methods for the design of experiments for mechanistic models when the response must be transformed to achieve symmetry and constant variance. The power transformation that is used is partially justified by a rule in analytical chemistry. Because of the nature of the relationship between the response and the mechanistic model, it is necessary to transform both sides of the model. Expressions are given for the parameter sensitivities in the transformed model and examples are given of optimum designs, not only for single-response models, but also for experiments in which multivariate responses are measured and for experiments in which the model is defined by a set of differential equations which cannot be solved analytically. The extension to designs for checking models is discussed.     

Estimation of Metabolic Rate Constants in PBPK‐Models from Liver Slice Experiments: What Are the Experimental Needs?

A mechanistic model is presented describing the clearance of a compound in a precision-cut liver slice that is incubated in a culture medium. The problem of estimating metabolic rate constants in PBPK models from liver slice experiments is discussed using identifiability analysis. From the identifiability problem analysis, it appears that in addition to the clearance, the compound's free fraction in the slice and the diffusion rate of the exchange of the compound between culture medium and liver slice should be identified. In addition, knowledge of the culture medium volume, the slice volume, the compound's free fraction, and octanol-water-based partition between medium and slice is presupposed. The formal solution for identification is discussed from the perspective of experimental practice. A formally necessary condition for identification is the sampling of parent compound in liver slice or culture medium. However, due to experimental limitations and errors, sampling the parent compound in the slice together with additional sampling of metabolite pooled from the medium and the slice is required for identification in practice. Moreover, it appears that identification results are unreliable when the value of the intrinsic clearance exceeds the value of the diffusion coefficient, a condition to be verified a posteriori.     

Gender-specific changes in students' sexual behaviors and attitudes at a southeastern university between 1973 and 1988.

This study investigated the gender-specific, self-reported sexual behaviors and attitudes of never-married college students attending a southeastern university in 1973 and 1988. Data were collected by means of a mailed questionnaire that remained essentially unchanged for both years. The authors found that both men and women reported an increase in heterosexual relationships that included sexual intercourse and a decrease in nonsexual relationships with the other gender. The majority of the students perceived themselves as adequately informed about sexuality and satisfied with their relationships, although the proportion of men who reported being satisfied with their relationships declined over the 15 years. The students indicated that sexuality education should focus primarily on information about AIDS and on preparation for marriage.     

Procedures and tables for the construction and selection of chain sampling plans ChSP-4A(c1, c2,)r-Part 4

In this part of the series, the notion of average total inspection (ATI) is introduced to ChSP-4A(c1, c2)r plans, minimizing ATI at a given process average, while protection to the consumer is given in terms of average outgoing quality limit and limiting quality level. The procedure is similar to that of Dodge and Roming.     

Determinants of housing quality: A comparison of white,African-American,and Hispanic single-parent women

This study examines housing quality among three groups of single-parent women: white, African-American, and Hispanic. Three indicators of housing quality—crowding, affordability, and satisfaction—are used to discover the extent to which these groups experience housing problems. This study also explores differences and similarities in the factors that precipitate problems in housing quality for these three groups of single parents. Findings suggest important differences and similarities in the nature of housing quality problems among white, African-American, and Hispanic single-parent women. The specified variables explained about 20% of the variance in crowding, housing affordability, and housing satisfaction. On measures of objective and subjective housing quality, white single mothers are better housed than their African-American or Hispanic counterparts. Hispanic single mothers have the largest housing cost burden and average more persons per household than the other groups. African-Americans are twice as likely as either group to live in low-quality housing and reported the lowest average satisfaction with their housing. Her research interests include housing and neighborhood assessment and women and public policy issues. She has recently published articles inUrban Affairs Quarterly andHousing and Society on housing and neighborhood assessment criteria among black urban households and the housing cost burden of various groups of female-headed households. She received her Ph.D. from Ohio State University. Her research interests include the housing adjustment behavior of women and public policy. She has recently completed her thesis on the role of noncustodial parents in determining the quality of life of their children. She is also the recipient of the Tessie Agan Award for research excellence from the American Association of Housing Educators for a paper titled “Unterstanding Constraints and Residential Satisfaction among Low-Income Single-Parent Families.”     

Uncertainty Analysis for Computer Model Projections of Hurricane Losses

Projecting losses associated with hurricanes is a complex and difficult undertaking that is wrought with uncertainties. Hurricane Charley, which struck southwest Florida on August 13, 2004, illustrates the uncertainty of forecasting damages from these storms. Due to shifts in the track and the rapid intensification of the storm, real-time estimates grew from 2 to 3 billion dollars in losses late on August 12 to a peak of 50 billion dollars for a brief time as the storm appeared to be headed for the Tampa Bay area. The storm hit the resort areas of Charlotte Harbor near Punta Gorda and then went on to Orlando in the central part of the state, with early poststorm estimates converging on a damage estimate in the 28 to 31 billion dollars range. Comparable damage to central Florida had not been seen since Hurricane Donna in 1960. The Florida Commission on Hurricane Loss Projection Methodology (FCHLPM) has recognized the role of computer models in projecting losses from hurricanes. The FCHLPM established a professional team to perform onsite (confidential) audits of computer models developed by several different companies in the United States that seek to have their models approved for use in insurance rate filings in Florida. The team's members represent the fields of actuarial science, computer science, meteorology, statistics, and wind and structural engineering. An important part of the auditing process requires uncertainty and sensitivity analyses to be performed with the applicant's proprietary model. To influence future such analyses, an uncertainty and sensitivity analysis has been completed for loss projections arising from use of a Holland B parameter hurricane wind field model. Uncertainty analysis quantifies the expected percentage reduction in the uncertainty of wind speed and loss that is attributable to each of the input variables.     

WHOSE GAY COMMUNITY? SOCIAL CLASS,SEXUAL SELF‐EXPRESSION,AND GAY COMMUNITY INVOLVEMENT

The visible and political gay community has been characterized as an increasingly middle-class, white institution. It is hypothesized that this middle-class nature requires economic and psychosocial resources that are not available to the working class and, thus, may limit the expression of sexual orientation for the working class. An analysis of data from the multicity Urban Men's Health Study supports this hypothesis. Nine of 14 hypothesized effects are statistically significant and indicate that working-class men who are homosexually active are less likely to describe themselves as gay, are more likely to have heterosexual experience, and are less likely to be involved in the gay community. Thus, it is important to incorporate class differences when addressing the social and the political dynamics of sexual orientation.     

Population Policy in Early Victorian England

This paper argues that the generally-held belief that there was no population policy in Great Britain during its fertility transition is incorrect. There were, in fact, clear and implicit and explicit policies in place by the early 19th Century which aimed at reducing population growth. These were negative, involving elimination of family allowances (the famous Poor Laws), and also positive, through subsidised emigration and ``transportation' of felons to the colonies. Moreover, a changed ``ideation' on the part of the nation's political, intellectual and spiritual leaders, changed norms about marriage and child-bearing, raising sharply the perceived economic and psychic cost of children. Lacking acceptable means to control pregnancies, many working class women resorted to abortion, infanticide and child abandonment to reduce their family size. The policy's actual impact on overall fertility is uncertain but it did constitute a deliberate attempt by society to affect demographic behaviour and outcomes.