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.     

Characterizations of geometric distribution through progressively Type-II right-censored order statistics

In this paper, we consider characterizations of geometric distribution based on some properties of progressively Type-II right-censored order statistics. Specifically, we establish characterizations through conditional expectation, identical distribution, and independence of functions of progressively Type-II right-censored order statistics. Moreover, extensions of these results to generalized order statistics are also sketched. These generalize the corresponding results known for the case of ordinary order statistics.     

Continuing Competence and Relicensure

Abstract

The purpose of licensing laws is to provide assurance of high quality service and to protect the public from incompetent practitioners. Safeguarding entrance to the professions by licensing examinations is one part of this responsibility which is entrusted to the professional boards. Assuring the continuing competence of practicing professionals is another part and a major challenge to every board of nursing throughout the United States.

A 1979 mail survey identified 18 states which have specific continuing education requirements for relicensure of nurses. In addition, three states have standards of practice incorporated in the rules and regulations governing the nursing profession.

Mandatory continuing education is a first step in the implementation of a system to assure the public of the continuing competency for practice of the professional nurse. It is acknowledgement, with the force of law, that continuous renewal of knowledge is a necessary condition for assuring competence. However, it is not sufficient in itself. Knowledge must be integrated in performance, which is the final test of competency. Thus, other system components that assure continuing competency must be developed and implemented. These include the identification of standards of acceptable performance, and the development and implementation of measures to evaluate practicing professionals and assure that they meet the performance standards. These measures include peer review, self-assessment, and recertification procedures. Successful implementation of a complete effective system will require the collaborative efforts of practicing nurses, their professional organizations, and the state boards of nursing.     

Unbiasedness of two-stage estimation and prediction procedures for mixed linear models

The traditional method for estimating or predicting linear combinations of the fixed effects and realized values of the random effects in mixed linear models is first to estimate the variance components and then to proceed as if the estimated values of the variance components were the true values. This two-stage procedure gives unbiased estimators or predictors of the linear combinations provided the data vector is symmetrically distributed about its expected value and provided the variance component estimators are translation-invariant and are even functions of the data vector. The standard procedures for estimating the variance components yield even, translation-invariant estimators.     

Energy and U.K. agriculture

This paper makes the point that although U.K. agriculture has become more efficient in many ways, it has become less efficient in its use of energy. Moreover, although farming utilises less than 3 per cent of national power energy consumption and produces over 40 per cent of the nation's food, there are no predominant users of energy in the U.K. Thus small savings in each individual industry, including agriculture, must be effected. How this can be achieved is discussed. But the paper concludes that it may well take another ‘energy crisis’ before farmers and growers respond by modifying their production systems accordingly.     

Product Introduction Strategies under Sequential Innovation for Durable Goods with Network Effects

When network effects are important and technology is rapidly improved, this study explores the relative optimality of five product introduction strategies of a durable goods manufacturer: (1) replacement, (2) skipping, (3) a delayed line, (4) shelving, and (5) line‐extension. Using a two‐period analytical model, we show how the type of compatibility—either full or backward compatibility—and the magnitude of the network effect influence the manufacturer's preference for the above strategies. Our analysis reveals that only the strategies (1)–(3) above can be optimal; and the optimal strategy varies with network strength. Further, the type of compatibility can dramatically change the profitability under each optimal strategy; for instance, while backward compatibility can increase the profitability of replacement under certain conditions, it always reduces the profitability of a delayed line. We also illustrate that if compatibility were a choice, although backward compatibility may be observed widely in practice, the parametric region for its optimality is relatively more restricted than that of full compatibility.     

The North American Career Development Partnership: Experiment in International Collaboration

This article describes how career development programs became the focus of an international partnership between the United States and Canada. Beginning in 1976 in the United States, the National Occupational Information Coordinating Committee (NOICC) and its State Occupational Information Coordinating Committees (SOICCs) developed training and materials that promote the use of occupational and labor market information. Similarly, in the early 1970s, Canada began to explore the feasibility of creating a computer‐based career information delivery system. What follows is the story of an unusual and significant international collaboration. It concludes with identification of lessons learned.     

Estimation of Error and Bias in Bayesian Monte Carlo Decision Analysis Using the Bootstrap

Bayesian Monte Carlo (BMC) decision analysis adopts a sampling procedure to estimate likelihoods and distributions of outcomes, and then uses that information to calculate the expected performance of alternative strategies, the value of information, and the value of including uncertainty. These decision analysis outputs are therefore subject to sample error. The standard error of each estimate and its bias, if any, can be estimated by the bootstrap procedure. The bootstrap operates by resampling (with replacement) from the original BMC sample, and redoing the decision analysis. Repeating this procedure yields a distribution of decision analysis outputs. The bootstrap approach to estimating the effect of sample error upon BMC analysis is illustrated with a simple value-of-information calculation along with an analysis of a proposed control structure for Lake Erie. The examples show that the outputs of BMC decision analysis can have high levels of sample error and bias.     

Analysis of the Bovine Spongiform Encephalopathy Maternal Cohort Study: the Discordant Case–Control Pairs

The progeny of the affected and non-affected dams in the bovine spongiform encephalopathy (BSE) cohort study were paired in terms of their farm of origin and approximate date of birth. This paper presents an exact logistic regression analysis that avoids modelling the differences between the pairs and so analyses only the discordant pairs. There is some evidence that the pairs in which the affected animal was born to the affected dam tend to be those in which the onset of BSE in the affected dam preceded or occurred soon after the calving. This suggests some occurrence of maternal transmission.