A PRESENT VALUE FORMULATION OF THE CLASSICAL EOQ PROBLEM*

The usual analysis of the deterministic economic order quantity problem seeks to minimize the average cost of inventory ordering and holding costs per unit time. An alternative approach described in this paper examines the present value of discounted costs over an infinite horizon. Differences in the solutions and implications of errors using the two methodologies are discussed.     

Modeling Competing Infectious Pathogens from a Bayesian Perspective: Application to Influenza Studies with Incomplete Laboratory Results

In seasonal influenza epidemics, pathogens such as respiratory syncytial virus (RSV) often co-circulate with influenza and cause influenza-like illness (ILI) in human hosts. However, it is often impractical to test for each potential pathogen or to collect specimens for each observed ILI episode, making inference about influenza transmission difficult. In the setting of infectious diseases, missing outcomes impose a particular challenge because of the dependence among individuals. We propose a Bayesian competing-risk model for multiple co-circulating pathogens for inference on transmissibility and intervention efficacies under the assumption that missingness in the biological confirmation of the pathogen is ignorable. Simulation studies indicate a reasonable performance of the proposed model even if the number of potential pathogens is misspecified. They also show that a moderate amount of missing laboratory test results has only a small impact on inference about key parameters in the setting of close contact groups. Using the proposed model, we found that a non-pharmaceutical intervention is marginally protective against transmission of influenza A in a study conducted in elementary schools.     

Panel Tests of Okun's Law for Ten Industrial Countries

Okun's Law is one of the most enduring stylistic facts in macroeconomics. This article uses new developments in trend/cycle decomposition to test Okun's Law for a panel of ten industrial countries, finding that Okun's original estimate for the U.S. of three points of real GDP growth for each one percent reduction in the unemployment rate now averages just under two points of real GDP growth for the sample countries. Pooled estimates for Europe are smaller than estimates for the rest of the sample. Also, this article finds that omission of capital and labor inputs may have biased previous estimates.     

Measuring Gay Populations and Antigay Hate Crime

Objectives . The study of crime directed at gay and lesbian targets is hampered by two measurement problems: Police agencies provide unreliable data on hate crime, and tract-level census data contain no direct information about gay or lesbian population density. This article attempts to gauge two quantities that cannot be measured directly or unambiguously: the size of the gay and lesbian populations and the number of hate crimes directed at gay and lesbian targets. Methods . Population data for New York City were gathered from market research lists and from a special tabulation of the 1990 Census. Hate crime data were obtained from the Anti-Violence Project and the New York Police Department. Confirmatory factor analysis was used to assess the reliability of each measure and the correlation between latent population density and hate crime. Results . Each of these measures offers a reliable means by which to assess cross-sectional differences in the population density and victimization of gay men. Census and police data prove to be inferior indicators of lesbian population density and antilesbian hate crime. For both men and women, population density is strongly correlated with the incidence of hate crime. Conclusions . Despite the fact that advocacy groups record many more antigay incidents than do the police, both sources of data are in agreement about where hate crimes occur. The strong correlation between population density and hate crime against gay men implies that Census data could be used to forecast the occurrence of hate crime in areas where no police records exist.     

Generating multivariate continuous data via the notion of nearest neighbors

Taylor and Thompson [15] introduced a clever algorithm for simulating multivariate continuous data sets that resemble the original data. Their approach is predicated upon determining a few nearest neighbors of a given row of data through a statistical distance measure, and subsequently combining the observations by stochastic multipliers that are drawn from a uniform distribution to generate simulated data that essentially maintain the original data trends. The newly drawn values are assumed to come from the same underlying hypothetical process that governs the mechanism of how the data are formed. This technique is appealing in that no density estimation is required. We believe that this data-based simulation method has substantial potential in multivariate data generation due to the local nature of the generation scheme, which does not have strict specification requirements as in most other algorithms. In this work, we provide two R routines: one has a built-in simulator for finding the optimal number of nearest neighbors for any given data set, and the other generates pseudo-random data using this optimal number.     

Parental substance misuse and child protection in a British sample. A survey of children on the child protection register in an inner London district office

The relationship between parental misuse of alcohol and/or illegal drugs and child maltreatment has received considerable attention in the USA, while comparatively few British studies have been published. In both countries, research suggests that it is a large and growing problem and that it has a significant negative impact on children. This study looks at 50 families with 95 children on the Child Protection Register (CPR) in an inner London area through an examination of files and social workers' rating of parental substance misuse as a child protection concern. Parental substance use, as defined by social workers, was considered by social workers to be a cause for concern in 52% of families. Alcohol (in 24% of families) and heroin (in 16%) were the main substances of concern. Substance misuse was strongly related to neglect and cases were twice as likely to be subject to care proceedings. Very little involvement of substance misuse professionals in child protection procedures was found. Different profiles of social work concern were found for alcohol and for illegal drugs. Reasons for this difference and areas for further research are discussed. Copyright © 2000 John Wiley & Sons, Ltd.