Warteschlangen-Modelle in der Produktionsplanung – Möglichkeiten und Grenzen

Production Management often tried to apply queueing models to describe the flow of products and parts. These approaches usually apply very simple queueing models. Due to mathematical problems implied by general waiting line models, an adaptation to real life problems fails often. In this paper, some simple models discussed in production management are presented and it is shown why they failed to be generalized. Afterwards, we try to find a way how to model the simple case of flow shop production using generalized queueing models: First decomposition of serial waiting lines and approximation of the system by a sequence of independent stations. Afterwards the approach of recent literature to consider again the entire system simultaneously is sketched, and it is argued that these approaches are restricted as well to small problems     

On computer generation of gamma random variables by rejection and composition procedures 2

The paper presents various algorithms for generating gamma random variables, by combining rejection and composition procedures. Two efficient algorithms are given for the case when the parameter of the gamma distribution is 0<v<l. For the case vl, several algorithms are given but they (except one), work reliably only for small values of v. Results of some computer tests together with FORTRAN subroutines are also presented.     

Selective Out-Migration from Florida

I test if selective out-migration of unhealthy seniors explains why disability rates are so much lower for Florida, as compared to the national average. This particular area of research is timely given the significant demographic changes relating to aging. Moreover, this study contributes to the body of literature examining migration with respect to disability and widowhood. Using State Federal Information Processing Standard (FIPS) and Public Use Microdata Areas (PUMA), I create national maps showing disability rates for the following age-groups: 50–59, 60–69, and 70+. After creating maps in ARCGIS and conducting univariate and clustering analysis on mobility disability and personal care limitation, I employ multinomial logit (MNL) analysis to test if individuals with disability are more likely to out-migrate from Florida. The regression analyses lend support to the relaxed Litwak and Longino (The Gerontologist, 27(3): 266–272, 1987) second-move hypothesis, which claims individuals with progressively worse health are more likely to undertake another move to be closer to family and friends. I state “relaxed” because the data does not allow one to determine the reason for migration—only that migration occurred during the past year. This research informs policy-makers to recognize that elderly in better health may migrate to places such as Arizona and Florida due to amenity-seeking behavior, but unhealthy elderly are more likely to leave these states due to assistance-seeking behavior. This out-migration can place excess demand on health services for the incoming regions, which requires state and local government to ensure resources are in place. Also noteworthy, my results are less likely to be flawed by erroneous age and sex data in the public use microdata samples (IPUMS) since I stack the 2006 and 2007 American Community Survey (ACS). A recent working studies by Alexander et al. (Inaccurate age and sex data in the Census PUMS files: Evidence and implications. Munich: CESifo, 2010) shows inaccuracies in the IPUMS for the 1 and 5% 2000 Census, the 2003–2006 ACS, the 2005–2007 3-year ACS, and the 2004–2009 current population survey (CPS) files.     

Who Benefits from Religion?

Many studies have documented the benefits of religious involvement. Indeed, highly religious people tend to be healthier, live longer, and have higher levels of subjective well-being. While religious involvement offers clear benefits to many, in this paper we explore whether it may also be detrimental to some. Specifically, we examine in detail the relation between religious involvement and subjective well-being. We first replicate prior findings showing a positive relation between religiosity and subjective well-being. However, our results also suggest that this relation may be more complex than previously thought. While fervent believers benefit from their involvement, those with weaker beliefs are actually less happy than those who do not ascribe to any religion—atheists and agnostics. These results may help explain why—in spite of the well-documented benefits of religion—an increasing number of people are abandoning their faith. As commitment wanes, religious involvement may become detrimental to well-being, and individuals may be better off seeking new affiliations.     

Follow-up surveys for census estimates of maternal mortality: experiences from Bolivia and Mozambique

Maternal mortality measurement through special census questions will be a common practice in the 2010 census round. To check this information or make it cause-specific, some countries have experimented with follow-up surveys containing verbal autopsies or triangulation with administrative data. However, follow-up studies can be costly and not without complications. In order to assess the benefits, two such experiences are discussed in detail (Bolivia, 2002; and Mozambique 2007–2008) and two others mentioned more briefly (Islamic Republic of Iran, 1996; and Democratic People’s Republic of Korea, 2008). In the former, several problems were apparent. In Mozambique, the follow-up survey used a cluster sample of 4.5% of deaths, from all causes. This design was adequate for the more common causes, but not for maternal mortality. Another problem was the large proportion of invalid cases (35.1%, plus 16% not verifiable) and the likelihood that there was a similar proportion of omitted deaths. The Bolivian census generated many invalid cases and missing ages, due in part to the flawed design of the questionnaire. This overburdened the follow-up, so that only 15% of the census deaths of women of reproductive age unrelated to pregnancy could be investigated. Once the false positives were eliminated, the results seem consistent with Growth Balance analyses, but the many classification errors compromise confidence in the results. Despite this mixed record of outcomes, it is believed that carrying out a limited number of similar studies in the current census round may be valuable, if appropriate lessons are learned from these experiences.     

Asperger’s Syndrome and the Decoding of Boredom,Interest, and Disagreement from Body Posture

Twenty Asperger’s Syndrome (AS) participants were compared with 20 matched neurotypical controls in their decoding of postural cues of boredom, interest, and disagreement. On a nonverbal matching task, the AS group performed as accurately as the controls, whereas on a verbal labeling task, AS participants made significantly more mistakes in labeling bored postures. Response times of the AS group were significantly slower than controls in their judgments of all three attitudes on both tasks, with the exception only of disagreeing postures on the verbal labeling task. It was hypothesized that these slower response times may reflect a feature-based cognitive processing style by AS participants. Proposed practical recommendations are to train AS individuals in the recognition of boredom, and to improve the speed with which they can recognize different attitudes.     

The Relationship Between Hope,Eustress, Self-Efficacy,and Life Satisfaction Among Undergraduates

The construct of eustress was studied alongside hope and self-efficacy, to explore how these constructs are related to life satisfaction among undergraduates. Questionnaires were administered to undergraduates to test the hypotheses that (1) as eustress levels increase, so will life satisfaction levels; (2) when eustress, hope, and self-efficacy are examined together, they will predict life satisfaction better than eustress alone; (3) eustress, hope, and self-efficacy will all be positively correlated with life satisfaction; and (4) self-efficacy will be the most positively correlated with life satisfaction. The results revealed a significant positive correlation between eustress and life satisfaction. A Hierarchical Linear Regression analysis revealed significant results supporting hypotheses 2 and 3, but not hypothesis 4. Results indicated that hope is the best predictor of life satisfaction. The work reported provides a reliable tool for measuring eustress, examines eustress in a new way at the academic level, and provides helpful information about student wellness to college administrators.     

Making Firefighters Deployable

Although sociologists have devoted a considerable amount of research to exploring high-risk organizations, they have not yet developed an adequate explanation as to why individuals working within such organizations place themselves in harm’s way and how organizations ensure they remain there. This article addresses this gap by analyzing how the United States Forest Service motivates wildland firefighters to participate in life-threatening activity. Drawing on ethnographic research and content analyses of official documents, it describes the process by which firefighters come to develop a specific disposition towards risk taking, a disposition through which they view firefighting as an activity void of danger, and how this disposition maintains its shape, and even grows stronger, after confronting its biggest challenge: the death of a firefighter.     

A Case for the Case Study: How and Why They Matter

In this special issue we have asked the contributors to make a case for the case study. The guest editors, Jeffrey Longhofer, Jerry Floersch and Eric Hartmann, intergrate ideas from across the disciplines to explore the complexties of case study methods and theory. In education, Gary Thomas explores the importance of ethnographic case studies in understanding the relationships among schools, teachers, and students. Lance Dodes and Josh Dodes use the case study to articulate a psychoanalytic approach to addiction. In policy and generalist practice, Nancy Cartwright and Jeremy Hardie elaborate a model for a case-by-case approach to prediction and the swampy ground prediction serves up to practitioners. Christian Salas and Oliver Turnbull persuasively write about the role of the case study in neuro-psychoanalysis and illustrate it with a case vignette. In political science, Sanford Schram argues for a bottom up and ethnographic approach to studying policy implementation by describing a case of a home ownership program in Philadelphia. Eric Hartman queers the case study by articulating its role in deconstructing normative explanations of sexuality. In applied psychology, Daniel Fishman describes a comprehensive applied psychology perspective on the paradigmatic case study. Richard Miller and Miriam Jaffe offer us important ways of thinking about writing the case study and the use of multi-media. Each contributor brings a unique perspective to the use of the case study in their field, yet they share practical and philosophical assumptions.     

Reduced Risk-Taking After Prior Losses in Pathological Gamblers Under Treatment and Healthy Control Group but not in Problem Gamblers

A group of pathological gamblers and a group of problem gamblers (i.e., gamblers at risk of becoming pathological) were compared to healthy controls on their risk-taking propensity after prior losses. Each participant played both the Balloon Analogue Risk Taking task (BART) and a modified version of the same task, where individuals face five repeated predetermined early losses at the onset of the game. No significant difference in risk-taking was found between groups on the standard BART task, while significant differences emerged when comparing behaviors in the two tasks: both pathological gamblers and controls reduced their risk-taking tendency after prior losses in the modified BART compared to the standard BART, whereas problem gamblers showed no reduction in risk-taking after prior losses. We interpret these results as a sign of a reduced sensitivity to negative feedback in problem gamblers which might contribute to explain their loss-chasing tendency.