Screening procedures using quadratic forms

In quality control, a performance variable having a two-sided specification limit is common for assessing lot quality. Sometimes it is difficult or impossible to measure the performance variable directly; for example, when testing is destructive, expensive, or when the performance variable is related to the lifetime of the product. However, it may happen that there are several concomitant variables which are easily measured and which correlate highly with the variable of interest. Thus, one may use measurements on these variables to select or screen product which will have a high conditional probability of meeting product specification. We consider this situation when all variables have a joint multivariate normal distribution and the specification limits on the performance variable are two-sided.     

A note on the accuracy of fisher's approximation to the large sample variance of an intraclass correlationa

The adequacy of Fisher's approximation to the large sample variance of an intraclass correlation is investigated in the context of family studies. It is found that the approximation is highly accurate in samples of moderately large size (≧ 30 families), and can also be used for significance-testing under a broad range of circumstances. The exact sampling of distribution of the intraclass correlation coefficient is also derived.     

Inferences from Cross-Sectional,Stochastic Frontier Models

Conventional approaches for inference about efficiency in parametric stochastic frontier (PSF) models are based on percentiles of the estimated distribution of the one-sided error term, conditional on the composite error. When used as prediction intervals, coverage is poor when the signal-to-noise ratio is low, but improves slowly as sample size increases. We show that prediction intervals estimated by bagging yield much better coverages than the conventional approach, even with low signal-to-noise ratios. We also present a bootstrap method that gives confidence interval estimates for (conditional) expectations of efficiency, and which have good coverage properties that improve with sample size. In addition, researchers who estimate PSF models typically reject models, samples, or both when residuals have skewness in the “wrong” direction, i.e., in a direction that would seem to indicate absence of inefficiency. We show that correctly specified models can generate samples with “wrongly” skewed residuals, even when the variance of the inefficiency process is nonzero. Both our bagging and bootstrap methods provide useful information about inefficiency and model parameters irrespective of whether residuals have skewness in the desired direction.     

Epidemic Mycoplasma Pneumoniae Infection at a College for the Deaf

Abstract

An outbreak of Mycoplasma pneumoniae infection affected up to 110 students and employees at a college for deaf students (Gallaudet). After the introduction of M. pneumoniae onto the campus in late August 1977, the disease spread slowly among the students; the last documented case occurred in mid-December. A thorough review of chart records, mail surveys, a dormitory survey, and a three-month surveillance of the student health service provided an intensive look at the epidemiology and clinical spectrum of a mild to moderately severe disease in the epidemic setting. A matched-pair analysis demonstrated a more serious clinical illness among patients with M. pneumoniae than other patients presenting with febrile respiratory illness. Appropriate antimicrobial therapy appeared to suppress a high antibody response to M. pnuemoniae. A follow-up serosurvey one year after this outbreak demonstrated diagnostic titers to M. pneumoniae in 11 of 30 patients with confirmed infection in the original epidemic.     

Models of Management System Standards: A Review of the Integration Issues

The subject of Integrated Management Systems in terms of quality, environmental and occupational health and safety management has become of increasing interest to researchers and business alike during the last 3 years or so. This paper focuses on a review of the various models of integration found in the academic literature and also those advocated by the standards bodies, such as the British Standards Institution and the International Organization for Standardization. A number of writers advocate alignment of ISO 9001 and ISO 14001 and present models to facilitate this; however, integration into a single standard is, in general, not favoured. Various models have been developed to overcome these difficulties, but the authors believe that none is completely satisfactory. It is considered that a model of integration based on the EFQM Model for Business Excellence will allow the limitation of the standards to be overcome and the total systems approach to integration to be facilitated.     

Measuring ambiguity attitude: (Extended) multiplier preferences for the American and the Dutch population

Empirical studies of ambiguity aversion often use measures that are not grounded in theory. This paper shows how a theoretically-founded measure of ambiguity aversion can be derived from Hansen and Sargent’s theory of multiplier preferences. Multiplier preferences are used in macroeconomics to capture model uncertainty. At the micro level, they have not been applied yet, because they do not permit ambiguity seeking, which is usually observed for a substantial proportion of subjects. We give a preference foundation for (extended) multiplier preferences accommodating both ambiguity aversion and ambiguity seeking and we propose a simple method to measure them using matching probabilities. We illustrate our method in two large representative samples (Dutch and American) and obtain the first micro estimates of multiplier preferences.     

Drinking Game Participation Among Undergraduate Students Attending National Alcohol Screening Day

Abstract

Objectives, Participants, Methods: Drinking game participation has increased in popularity among college students and is associated with increased alcohol consumption and alcohol-related problems. The current study investigated drinking game participation among 133 undergraduates attending National Alcohol Screening Day (NASD) in April of 2007. Results: A large percentage of the sample reported lifetime (77%) and recent (52%) drinking game participation. Males were more likely to report recent participation and reported higher levels of consumption while playing drinking games. Drinking game participants were more likely to experience a range of alcohol-related problems, and the relationship between drinking game participation and alcohol-related problems was mediated by weekly alcohol consumption. Conclusions: These results suggest that drinking game participation is a risk factor for elevated levels of alcohol consumption and alcohol-related problems. Programs should be developed to educate students about the risks of drinking game participation, and prevention programs like NASD should address drinking games.