Estimating reference ranges from stratified two-stage samples

We present methodology for estimating age-specific reference ranges by using data from two-stage samples. On the basis of the information obtained in the first stage, the initial sample is stratified and random subsamples are drawn from each stratum, where the selection probabilities in this second-stage sampling may be different across strata in the population. The variable for which the reference ranges are to be established is measured at the second phase. The approach involves maximum likelihood estimation of the parameters of the age-specific distributions and separate estimation of the population stratum probabilities. These are combined to yield estimates of the quantiles of interest. The issue of variance estimation for the estimated quantiles is also addressed. The methodology is applied to the estimation of reference ranges for a cognitive test score in a study of non-demented older Japanese-Americans.     

Ceremonies of Governance: Perspectives on the Role of the Audit Committee

The widespread establishment of auditcommittees in large UK companies cannot be explainedby evidence of their effectiveness as a mechanism ofcorporate governance, since such evidence is sparse.In this paper, participants' accounts of auditcommittee activity are explored, using conceptsdeveloped in actor-network theory. The paper suggeststhat a possible explanation for the popularity ofaudit committees may be found in their ceremonialfunction, which, through a comforting display ofconcern for corporate governance standards, validatescompany legitimacy and enables access to resources forsurvival and growth.The paper briefly reviews the literature on auditcommittee effectiveness, noting its limitations, anddescribes a qualitative study of audit committeeactivity through the perceptions of participants –audit committee chairs and members, finance directors,internal and external auditors. The actor-networkconcept of `translation' is used to frame theseperceptions, highlighting the ceremonial components ofaudit committee meetings and the performance ofquestioning. It is argued that, aside from anysubstantive audit committee activity, this ceremonialperformance plays an important part in offeringcomfort and reassurance to investors and lenders.     

Factors Related to Successful Outcomes Among Preschool Children Born to Low‐Income Adolescent Mothers

The purpose of this study was to describe how the experiences and circumstances of the most successful children born to low‐income adolescent mothers differed from the experiences and circumstances of the least successful children over the first 54 months of their lives. Success was defined as scoring in the top quartile for this sample on the Peabody Picture Vocabulary Test‐Revised (PPVT‐R) when the children were 54 months old and about to make the transition to kindergarten. The experiences of the 22 children with the highest scores on the PPVT‐R were contrasted with the experiences of the 22 children who had the lowest scores on the PPVT‐R for this sample. The two groups differed markedly on measures of caregiving and home environment assessed when the children were 12, 24, 36, and 54 months old. In addition, mothers of the most successful children achieved more years of education, were more likely to be employed, had fewer children on average, tended to live in more desirable neighborhoods, and were more likely to be living with a male partner. Case studies are also presented on four families (two from the most successful group and two from the least successful group) to further illustrate how the experiences and circumstances of children in the two groups differed.     

Statistical precision of categorical PATH observations of trunk posture

Background: Field studies assessing biomechanical occupational exposures frequently utilize direct observation. PATH (Postures, Activities, Tools, and Handling) is a tool for systematically observing occupational exposures during non-cyclic or long, irregular-cycle jobs. While PATH has been used in many studies, its statistical performance under different data collection strategies has not yet been investigated. The purpose of the current study was to examine this issue. Methods: Data from labourers performing the four tasks comprising a 'Jacking Pit Construction' operation was extracted from a previously collected data set. Using a probability based re-sampling bootstrap approach, categorical trunk posture exposure data was compared across nine simulated data collection strategies. Results/Conclusion: At the operational level, dispersion curves showed consistent trends of increased precision with increased sizes of the data set and curves tended to intersect at the expected value seen in the parent data set. At the task level, curves did not always follow the predicted pattern, highlighting the potential pitfalls of using PATH for infrequent tasks and the striking effect that individual workers can have on group exposure estimates of such tasks.     

The deaf and the classroom design: a contribution of the built environmental ergonomics for the accessibility

In any concept of school design, classroom occupies the central place. Dimensions, lighting, the equipment needed, ventilation are old questions already answered, even in form of laws and standards adopted. However, the best use of available materials and physical conditions of comfort is not sufficient for a classroom design guaranteed success. The classroom should provide deaf students elements to facilitate the learning process, eliminating as much as possible the obstacles created by lack of hearing and allowing them to have the same access to learning as a listener student. As users of a school building, teachers, students, parents and staff are the best evaluators of the physical environment of schools. The environmental comfort is a largest ally of pedagogy. The learning comes from the perception and the concentration of students in the classroom. The purpose of this study is to detect the role of direct perception (physical) and indirect (intangible) elements that informs and have symbolic value, and propose layouts for accessible classrooms to deaf students. The ergonomics of the built environment evaluation methods could use the participatory design method tools as basis to assessing how users perceive and use the school environment.     

Methodological proceedings to evaluate the physical accessibility in urban historic sites

Historic urban sites are set by cultural and social diversities, generating multiple activities and use and access to these sites should be available to all people including those with disabilities. Taking into consideration that using the same methodology that was used in different historic sites researches with positive results facilitates replication, we aimed to develop methodological procedures that identify conditions of physical accessibility in open public spaces and access to public buildings in historic urban sites to support proposals about design requirements for improvements to the problems diagnosed and control inadequacies of the physical environment. The study methods and techniques from different areas of knowledge culminated in a proposal built with an emphasis on user participation that could be applied with low cost and in relatively short period of time.