A Simulation Study of Work-in-Process Inventory Drive Systems and their Effect on Operational Measurements

This simulation study compares three operational measures of performance through the exploration of three work-in-process (WIP) inventory drive systems and their associated inventory buffer characteristics. The three drive systems under study are a push, a pull and a hybrid push-pull system. While these systems have many aspects in common, their buffer management systems do not. The data analysis was based on information gathered from three computer-simulated flow shop assembly lines all operating in the same environment. Hypotheses concerning the operational performance measurements were established, independent variables were controlled and manipulated and a conclusion was drawn as to which system would afford the operation optimum results. While inventory has traditionally been considered and is currently being shown as an asset from an accounting point of view, it is obvious from the findings of this study, that excess WIP inventory, above the minimal requirements for production, may have a negative effect on the operational measurements evaluated.     

Modelling Variability in the Branching Structure of Strawberry Inflorescences

The branching structure of inflorescences of the cultivated strawberry ( Fragaria × ananassa Duch.) is very variable. This paper demonstrates that some aspects of this variability are well described by a simple stochastic model of branching that has two adjustable parameters. The model is shown to provide a good fit to data from a set of almost 700 inflorescences of the cultivar Elsanta, collected over two successive years. For one parameter the maximum likelihood estimator is a moment estimator which is fully efficient even if the detailed branching structure of the inflorescences is not recorded. This parameter provides a convenient summary of branching vigour. The maximum likelihood estimator of the second parameter must be determined iteratively and can be quite inefficient unless the full branching structure is recorded. The model demonstrates that branching structure is affected by the order in which inflorescences emerge on the plant.     

Family support: A review of the literature on families of adolescents with disabilities

ABSTRACT

For all youth, adolescence is a time of great change, marked by multiple transitions. For those with disabilities, these transitions can be especially challenging for the youth and their families. Although families of adolescents with disabilities often require support, it is unclear what types of assistance are most helpful. To understand the responsibilities of and, correspondingly, supports needed for parents and siblings, the authors conducted a comprehensive literature review. Specifically, the authors examined the literature to identify the supports that families provide to their adolescent relatives with disabilities, the impacts of caring for an adolescent relative with a disability, and the assistance that families receive. The authors conclude by discussing implications for future research about family support.     

Effects of Risk and Time Preference and Expected Longevity on Demand for Medical Tests

Despite their conceptual importance, the effects of time preference, expected longevity, uncertainty, and risk aversion on behavior have not been analyzed empirically. We use data from the Health and Retirement Study (HRS) to assess the role of risk and time preference, expected longevity, and education on demand for three measures used for early detection of breast and cervical cancer—regular breast self-exams, mammograms, and Pap smears. We find that individuals with a higher life expectancy and lower time preference are more likely to undergo cancer screening. Less risk averse individuals tend to be more likely to undergo testing.     

An R2criterion based on optimal predictors

The predictor that minimizes mean-squared prediction error is used to derive a goodness-of-fit measure that offers an asymptotically valid model selection criterion for a wide variety of regression models. In particular, a new goodness-of-fit criterion (cr²) is proposed for censored or otherwise limited dependent variables. The new goodness-of-fit measure is then applied to the analysis of duration.     

Ecological Concern, Attitudes, and Social Norms in Voting Behavior

Using a theoretical framework not previously tested in environmentalresearch, this study investigates the indirect relationshipbetween ecological concern and voting behavior. Results indicatethat the effects of ecological concern are mediated by attitudinal,normative, and behavioral intention variables. The results alsoprovide a partial test of the validity of Ajzen and Fishbein'sTheory of Reasoned Action. Key environmental, public policy,and communications implications are discussed.     

Allocation of research and development funds: A zero-one goal programming approach

The research and development project selection process is one of the most difficult and important problems faced by management. It is typically complicated by indivisibility of projects and multiple and conflicting objectives, in addition to limitations on funding, facilities, and qualified researchers. In this paper a case example involving a high technology electrical equipment manufacturer is developed to illustrate this problem using zero—one goal programming to accommodate indivisibility of projects in addition to multiple and conflicting goals. The model presented is an attempt to provide managers with a robust tool for allocating scarce resources among research and development projects.