Revisiting retesting in the estimation of proportions by group testing

In the estimation of a proportion p by group testing (pooled testing), retesting of units within positive groups has received little attention due to the minimal gain in precision compared to testing additional units. If acquisition of additional units is impractical or too expensive, and testing is not destructive, we show that retesting can be a useful option. We propose the retesting of a random grouping of units from positive groups, and compare it with nested halving procedures suggested by others. We develop an estimator of p for our proposed method, and examine its variance properties. Using simulation we compare retesting methods across a range of group testing situations, and show that for most realistic scenarios, our method is more efficient.     

Environmental changes to increase physical activity: perceptions of older urban ethnic-minority women

Despite the numerous benefits of physical activity, older adults continue to be more sedentary than their younger counterparts, and sedentary behavior is more prevalent among older racial and ethnic minorities than among Whites. This study used the nominal group technique (NGT) to examine participants' perceptions of what neighborhood environmental changes would encourage greater physical activity for older African American and Hispanic women. Participants age 50-75 years were recruited from 2 urban community health clinics. Nine NGT sessions (45 participants) were conducted. The women were asked what changes in their neighborhood environment would encourage them to become more physically active. Responses to the research question were tabulated, and qualitative analysis was used to identify themes and categories. Major categories were physical environment changes, safety, and activities/social support. Although the physical environment received the greatest number of points, concerns for personal safety cut across categories. Participants indicated the need for more facilities in which to be active.     

Better practices in parent engagement: lessons from the USA and England

This paper undertakes an international comparison of parent engagement in the USA and England. Research from both countries is reviewed to establish the extent to which parent engagement is achieving the benefit of an improved fit between need and services and what, if any, differences exist between the experiences of parents in the USA and England. Despite some unique differences, research from both countries identifies similar experiences among parents. Those studies indicate that parent engagement is not yet contributing to the provision of services that are more timely, appropriate, or adequate in meeting parent need. The barriers to achieving a better fit between needs and services are explored and system-wide issues that limit the effectiveness of engagement with parents are discussed. The paper presents the Munro Review of Child Protection in England as a catalyst for change in improving the child welfare system's approach to parent engagement and establishing a better fit between needs and services. Consideration of the applicability of the Munro Review findings to the USA child welfare system or replication of such a review is proposed.     

Health and community services for trafficked women: an exploratory study of policy and practice

The trafficking of women has attracted considerable international and national policy attention, particularly since the UN Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women and Children (2000), of which the Australian Government has been a signatory since 2005. The provision of health and community services for trafficked women is a central feature of this Protocol, but in Australia service provision is made difficult by how trafficked women are understood and treated in policy and legal terms. This study aimed to explore the provision of health and community services for trafficked women in the Greater Sydney region through a series of interviews with government and non‐government organisations. The findings reveal that services have been inaccessible as a result of sparse, uncoordinated, and poorly funded provision. The major obstacle to adequate and appropriate service provision has been a national policy approach focusing on ‘border protection’ and criminalisation rather than on trafficked women and their human rights. We conclude that further policy development needs to focus on the practical implications of how such rights can be translated into the delivery of health and community services that trafficked women can access and be supported by more effectively.     

Caffeine intake is not associated with serum testosterone levels in adult men: cross-sectional findings from the NHANES 1999–2004 and 2011–2012

Objective: The association of caffeine intake with testosterone remains unclear. We evaluated the association of caffeine intake with serum testosterone among American men and determined whether this association varied by race/ethnicity and measurements of adiposity.

Methods: Data were analyzed for 2581 men (≥20?years old) who participated in the cycles of the NHANES 1999–2004 and 2011–2012, a cross-sectional study. Testosterone (ng/mL) was measured by immunoassay among men who participated in the morning examination session. We analyzed 24-h dietary recall data to estimate caffeine intake (mg/day). Multivariable weighted linear regression models were conducted.

Results: We identified no linear relationship between caffeine intake and testosterone levels in the total population, but there was a non-linear association (p_nonlinearity?p_nonlinearity?≤?.03 both) and only among men with waist circumference <102?cm and body mass index <25?kg/m² (p_nonlinearity?Conclusion: No linear association was identified between levels of caffeine intake and testosterone in US men, but we observed a non-linear association, including among racial/ethnic groups and measurements of adiposity in this cross-sectional study. These associations are warranted to be investigated in larger prospective studies.     

Exact Confidence Intervals for Proportions Estimated by Group Testing with Different Group Sizes

Group testing is the process of combining individual samples and testing them as a group for the presence of an attribute. The use of such testing to estimate proportions is an important statistical tool in many applications. When samples are collected and tested in groups of different size, complications arise in the construction of exact confidence intervals. In this case, the numbers of positive groups has a multivariate distribution, and the difficulty stems from a lack of a natural ordering of the sample points. Exact two‐sided intervals such as the equal‐tail method based on maximum likelihood estimation, and those based on joint probability or likelihood ratio statistics, have been previously considered. In this paper several new estimators are developed and assessed. We show that the combined tails (or Blaker) method based on a suitable ordering statistic, is the best choice in this setting. The methods are illustrated using a study involving the infection prevalence of Myxobolus cerebralis among free‐ranging fish.     

Using Student Course Evaluations: Findings,Issues, and Recommendations

Abstract

Although university administrators widely use student course evaluations (SCEs) in evaluating faculty performance, faculty members are skeptical about what SCEs actually measure. Faculty lack information about SCE reliability and validity and whether administrators use them fairly in making personnel decisions. This article reports research findings on factors that threaten the reliability and validity of SCEs. It provides recommendations for minimizing these threats. It reports findings of a recent survey of social work deans on their opinions about and use of SCEs. The article also presents recommendations to enhance the use of SCEs.     

Bias correction of estimated proportions using inverse binomial group testing

Group testing, in which individuals are pooled together and tested as a group, can be combined with inverse sampling to estimate the prevalence of a disease. Alternatives to the MLE are desirable because of its severe bias. We propose an estimator based on the bias correction method of Firth (1993), which is almost unbiased across the range of prevalences consistent with the group testing design. For equal group sizes, this estimator is shown to be equivalent to that derived by applying the correction method of Burrows (1987), and better than existing methods. For unequal group sizes, the problem has some intractable elements, but under some circumstances our proposed estimator can be found, and we show it to be almost unbiased. Calculation of the bias requires computer‐intensive approximation because of the infinite number of possible outcomes.     

Estimation of proportions by group testing with retesting of positive groups

Abstract

When estimating a proportion p by group testing, and it is desired to increase precision, it is sometimes impractical to obtain additional individuals but it is possible to retest groups formed from the individuals within the groups that test positive at the first stage. Hepworth and Watson assessed four methods of retesting, and recommended a random regrouping of individuals from the first stage. They developed an estimator of p for their proposed method, and, because of the analytic complexity, used simulation to examine its variance properties. We now provide an analytical solution to the variance of the estimator, and compare its performance with the earlier simulated results. We show that our solution gives an acceptable approximation in a reasonable range of circumstances.