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.     

Development and Consideration of Global Policies for Managing the Future Risks of Poliovirus Outbreaks: Insights and Lessons Learned Through Modeling

The success of the Global Polio Eradication Initiative promises to bring large benefits, including sustained improvements in quality of life (i.e., cases of paralytic disease and deaths avoided) and costs saved from cessation of vaccination. Obtaining and maintaining these benefits requires that policymakers manage the transition from the current massive use of oral poliovirus vaccine (OPV) to a world without OPV and free of the risks of potential future reintroductions of live polioviruses. This article describes the analytical journey that began in 2001 with a retrospective case study on polio risk management and led to development of dynamic integrated risk, economic, and decision analysis tools to inform global policies for managing the risks of polio. This analytical journey has provided several key insights and lessons learned that will be useful to future analysts involved in similar complex decision-making processes.     

The Role of the Communal Voice in Constructing Meaning at the Funeral of an Infant Child in a Quaker Community in Costa Rica

This article attempts to capture the ongoing process of the construction of a “communal voice” out of the idiosyncratic “individual voices” of diverse people in a remote Quaker Community in the rainforest mountains of Costa Rica. The communal story is investigated through the rituals surrounding the death of an infant child. The constant dialogue is examined as the Cliffedgians struggle with issues of community/individualism, tolerance/conviction, and simplicity/benefit. Attention is also given to the communal construction of taboo areas of discourse.     

The Development of Vocational Realism in Black American College Students

A total of 172 Black students completed a survey of biographical, educational, and vocational information about themselves and their immediate relatives. The results indicated that educational realism tended to increase across the college years. There was no difference in satisfaction with school or intent to leave school as a function of educational realism or salary realism. Vocationally realistic male and female students did not differ in age.     

“FOI POR ACASO”*:

Everyone knows that most of the things that happen to them happen “by accident,” and this is particularly true of the things that are most important to us, like our choice of a career or a mate. Yet social science theory looks for determinate causal relationships, which do not give an adequate account of this thing that “everyone knows.” If we take the idea of “it happened by chance” seriously, we need a quite different kind of research and theory than we are accustomed to.     

Evaluating the Efficacy of a Mental Models Approach for Improving Occupational Chemical Risk Protection

Chemical risk protection in the workplace relies partly on informing workers about possible risks using material safety data sheets (MSDS). This article reports on phase 2 of a project (phase 1 reported in Cox et al.), which employed a mental models approach to improve on data sheets as communicative interventions for perchloroethylene in dry cleaning and rosin-based solder flux in the electronics industry within small businesses in the United Kingdom (small enterprises (SEs) < 25 employees in the workplace). It focuses on the efficacy of a multimethod evaluation strategy to assess (1) the capacity of a mental models approach to yield contextually relevant data for intervention design and (2) the effectiveness of the strategy itself in validating the mental models data. The evaluation was conducted using postal questionnaires and semi-structured verbal protocols to provide responses to the alternative intervention content and to prioritize risk messages. User discussion groups were then employed, particularly as a means of establishing whether contextual information could be obtained that would differ qualitatively from the kind elicited through individual (semi) structured methods. We conclude that the mental models approach as part of an iterative process including systematic multimethod evaluation is successful in supporting the design of relevant communications to the users of chemicals. The overall viability of communicative interventions in the context of health and safety in small businesses remains in question. Future research might aim to develop a more holistic approach to interventions in complex occupational contexts.     

Stories in Decisions: How At-Risk Individuals Decide to Request Predictive Testing for Huntington Disease

Huntington Disease (HD) is a hereditary neurological disease that typically occurs in mid-life. There is no prevention or cure, but persons at risk may request predictive genetic testing to learn whether or not they will develop the disease later in life. Many studies describe why such persons request this knowledge. Few consider how people actually make this novel decision. Drawing on in-depth interviews with sixteen test candidates, this article differentiates three types of stories about—as well as embedded in—the experience of deciding. Each type of story sheds a different light on the meaning and experience of making this decision. Stories of having to know reveal that decision-making may be experienced as a self-evident act while stories of evolving toward it feature an incremental process of weighing up the implications. Stories of taking the decision feature a pivotal point which involves the narrator in seeing anew the opportunity to make a choice. Emphasizing previously neglected temporal, biographical and phenomenological dimensions of decision-making, this typology underscores the relevance of narrative in complex processes of decision-making. It also illustrates the inadequacy of understanding decision-making purely through the lens of rational choice.     

Generic Strategies and Business Performance: an Empirical Study of the Screw Machine Products Industry

Select businesses in industry may attempt to compete through distinct strategies. But some may be successful in adopting distinct strategic profiles while others may not prove successful. In this study it was expected that six different groups of businesses might be present in the empirical exploration – those competing successfully with the low cost strategy and those competing unsuccessfully with this strategy; those competing successfully with the differentiation strategy and those competing unsuccessfully with this strategy; and those competing successfully with low cost and differentiation strategies and those competing unsuccessfully with these strategies. The results of the investigation portray the presence of three strategic profiles. They are unsuccessful low cost businesses with the lowest performance, unsuccessful differentiated businesses with the second lowest performance, and successful businesses with combination strategies with the highest performance.     

Managing the introduction of new technology

Most of the existing literature on the implications of new technology focuses on either its ‘impact’ or the social choices that lie behind strategies for its introduction into work organisations. The problems of managing the implementation of new technology have yet to be extensively examined despite this being one of the most critical aspects in the process of technological change. The findings from two case studies are presented which show how managers in the organisations concerned developed contrasting approaches to the problem of implementation in the context of opportunities and constraints presented by product markets and technological advance. Similarities between the two approaches are identified, in particular the role played by top management support in facilitating the acceptance of the new technology. The argument that management is able to develop a single unitary strategy towards the introduction of new technology is rejected in favour of a view of managerial actions as a series of flexible and changing sub-strategies associated with different stages in the process of change.     

Stigma Management Among Gay/Bisexual Men with HIV/AIDS

People with HIV infection are subjected to prejudice, discrimination and hostility related to the stigmatization of AIDS. To manage the stigma of their disease, they mount complex coping strategies. This paper reports results from a qualitative study that examined gay/bisexual men's experiences of living with HIV infection. Unstructured interviews from a diverse sample of 139 men were analyzed to examine how men coped with AIDS-related stigma. We discerned a variety of stigma management strategies that could be arranged along a continuum from reactive to proactive based on the extent to which they implicitly accepted or challenged the social norms and values that underlie the stigmatization of HIV/AIDS. Reactive strategies to cope with stigma involve defensive attempts to avoid or mitigate the impact of stigma, but imply acceptance of the underlying social norms and values that construct the stigma. Examples of reactive strategies include hiding one's HIV status, presenting one's illness as a less stigmatizing one (e.g., cancer), or distancing one's self from more damaging aspects of AIDS-stigma (e.g., attributing infection to blood transfusion). Proactive strategies challenge the validity of the stigma and imply disavowal and resistance of the social norms and values that underlie the stigma. Examples of proactive strategies include engaging in public educational efforts that address misperceptions about HIV transmission and social activism to change the social and political conditions that affect PWA/HIV.