Discriminant Analysis Using Least Absolute Deviations

Several linear programming methods have been suggested as discrimination procedures. A least absolute deviations regression procedure is developed here which is simpler to use and does not suffer from any lack of invariance. A simulation study shows it to be at least as effective as any of the methods previously discussed for normal and heavy-tailed distributions.     

Neoplasia masquerading as physical abuse

We describe three children with organic disease presenting as possible physical abuse. The first child was an infant with an ‘unexplained’ transverse fibular fracture, who was initially placed on the child protection register. Subsequent progress and investigation revealed that the fracture was caused by a haemangioma arising from the surrounding tissues. Two further children presented with bruising, in one case due to acute lymphoblastic leukaemia and in the other neuroblastoma. In both, the correct diagnosis became evident following assessment by an experienced paediatrician. These cases demonstrate the importance of obtaining an accurate history and of performing a careful examination when considering physical abuse, but also the need to review that diagnosis if subsequent contradictory evidence comes to light. Copyright © 2000 John Wiley & Sons, Ltd.     

THE HERMITE DISTRIBUTION AS A MODEL OF DEMAND DURING LEAD TIME FOR SLOW-MOVING ITEMS

Heretofore, the Poisson and the Laplace distributions have been used to model demand during lead time for slow-moving items. In this paper, we present a Poisson-like distribution called the Hermite. The advantage of the Hermite is that it is as simple to use as the Poisson and the Laplace are. Moreover, the Hermite is the exact distribution of demand during lead time when unit demand is Poisson, P(Λ), and lead time is normally distributed, N(μ, σ²), so long as (μ/σ²)≥Λ. Thus, the Hermite can enhance the accuracy of analysis as well as add to the tools available to the analyst.     

An Evolutionary Algorithm for Sequencing Production on a Paced Assembly Line

A new sequencing method for mixed‐model assembly lines is developed and tested. This method, called the Evolutionary Production Sequencer (EPS) is designed to maximize production on an assembly line. The performance of EPS is evaluated using three measures: minimum cycle time necessary to achieve 100% completion without rework, percent of items completed without rework for a given cycle time, and sequence “smoothness.” The first two of these measures are based on a simulated production system. Characteristics of the system, such as assembly line station length, assembly time and cycle time, are varied to better gauge the performance of EPS. More fundamental variation is studied by modeling two production systems. In one set of tests, the system consists of an assembly line in isolation (i.e., a single‐level system). In another set of tests, the production system consists of the assembly line and the fabrication system supplying components to the line (i.e., a two‐level system). Sequence smoothness is measured by the mean absolute deviation (MAD) between actual component usage and the ideal usage at each point in the production sequence. The performance of EPS is compared to those of well‐known assembly line sequencing techniques developed by Miltenburg (1989), Okamura and Yamashina (1979), and Yano and Rachamadugu (1991). EPS performed very well under all test conditions when the criterion of success was either minimum cycle time necessary to achieve 100% production without rework or percent of items completed without rework for a given cycle time. When MAD was the criterion of success, EPS was found inferior to the Miltenburg heuristic but better than the other two production‐oriented techniques.     

Diagnosing physical abuse using Bayes' Theorem: a preliminary study

Objectives. To perform a preliminary study to compare the patterns of bruises in a physically abused group of children and a control group; to investigate whether these could be modelled statistically to enable probabilities of typical bruise patterns to be calculated; to apply Bayes' Theorem to find the probability that a child with a given bruise pattern has been the subject of physical abuse. Design. An observational study. Setting. Cardiff and Vale of Glamorgan. Subjects. Children who have suffered child physical abuse, 0–14 years. The diagnosis was confirmed at a case conference in all cases. A control group of 289 children who presented to the Accident and Emergency Department at the Cardiff Royal Infirmary after an accidental injury. Main outcome measures. The distribution bruise pattern in three regions of the body. The posterior probability of abuse for a given bruise pattern. Results. The bruise distribution in physically abused and control children was well described by a negative binomial distribution. There was a different distribution for the three different regions of the body in physically abused children. The bruising frequency and distribution for the physically abused group was very different from that of the controls. We were able to use parameters derived from these distributions to calculate posterior probabilities of physical abuse given a particular pattern of bruises using Bayes' Theorem. Conclusions. This preliminary study demonstrates that we can use Bayes' Theorem to combine prior probabilities of physical abuse with observed patterns of bruising in given children to obtain posterior probabilities of abuse. This principle has considerable potential for better diagnosis of the physically abused child. © 1998 John Wiley & Sons, Ltd.     

Dogmatism and Systems Development Personnel Performance

This research explores the relationship between the personal variable, dogmatism, and the performance evaluations of systems analysts within a Fortune 500 company. The Rokeach Dogmatism Scale was used to measure the analysts’ level of dogmatism. The analysts’ performance measurement was the product of the company's annual evaluation process. The results of the research indicate that personnel with the highest dogmatism scores generally receive the extreme performance ratings. The results of this study provide further support to consider dogmatism as an important personal variable influencing systems analyst job performance.     

Do Marriage and Cohabitation Provide Benefits to Health in Mid-Life? The Role of Childhood Selection Mechanisms and Partnership Characteristics Across Countries

Extensive research has found that marriage provides health benefits to individuals, particularly in the U.S. The rise of cohabitation, however, raises questions about whether simply being in an intimate co-residential partnership conveys the same health benefits as marriage. Here, we use OLS regression to compare differences between partnered and unpartnered, and cohabiting and married individuals with respect to self-rated health in mid-life, an understudied part of the lifecourse. We pay particular attention to selection mechanisms arising in childhood and characteristics of the partnership. We compare results in five countries with different social, economic, and policy contexts: the U.S. (NLSY), U.K. (UKHLS), Australia (HILDA), Germany (SOEP), and Norway (GGS). Results show that living with a partner is positively associated with self-rated health in mid-life in all countries, but that controlling for children, prior separation, and current socio-economic status eliminates differences in Germany and Norway. Significant differences between cohabitation and marriage are only evident in the U.S. and the U.K., but controlling for childhood background, union duration, and prior union dissolution eliminates partnership differentials. The findings suggest that cohabitation in the U.S. and U.K., both liberal welfare regimes, seems to be very different than in the other countries. The results challenge the assumption that only marriage is beneficial for health.