A Bayesian Approach for Analyzing Results of Vehicle Collision Tests

Certain motor vehicle safety standards stipulate a collision test speed and a set of performance criteria that vehicles must satisfy during or after the collision test. For example, Federal Motor Vehicle Safety Standard 301 requires a 30 mile per hour (mph) barrier collision and specifies a certain maximum allowable limit on the total spillage of fuel. Vehicle designs are required to meet this standard; however, when collision tests are conducted at speeds higher than the standard, vehicles do not always satisfy the performance criteria. This paper develops a mathematical model for estimating the probability of meeting the standard by using a Bayesian framework to incorporate engineering judgment with collision test results. The model is based on the idea that there are random features to a vehicle's ability to meet performance standards in a collision, especially at such elevated speeds. Example calculations are included to illustrate the estimation of the probability of meeting the standard and to compare it with a maximum likelihood approach.     

On the Joint Lot-Sizing Problem with Zero Setup Costs

In a recent paper, Pinto and Mabert [5] presented a lot-sizing rule and an improvement procedure for the joint lot-sizing problem with zero setup costs. We show that this procedure often yields infeasible schedules. We also present and discuss two interesting properties of the joint lot-sizing problem with zero setup costs. A numerical example to illustrate the second property is provided.     

On the computation of the noncentral <Emphasis Type="Italic">F</Emphasis> and noncentral beta distribution

Unfortunately many of the numerous algorithms for computing the comulative distribution function (cdf) and noncentrality parameter of the noncentral F and beta distributions can produce completely incorrect results as demonstrated in the paper by examples. Existing algorithms are scrutinized and those parts that involve numerical difficulties are identified. As a result, a pseudo code is presented in which all the known numerical problems are resolved. This pseudo code can be easily implemented in programming language C or FORTRAN without understanding the complicated mathematical background. Symbolic evaluation of a finite and closed formula is proposed to compute exact cdf values. This approach makes it possible to check quickly and reliably the values returned by professional statistical packages over an extraordinarily wide parameter range without any programming knowledge. This research was motivated by the fact that a very useful table for calculating the size of detectable effects for ANOVA tables contains suspect values in the region of large noncentrality parameter values compared to the values obtained by Patnaik’s 2-moment central-F approximation. The cause is identified and the corrected form of the table for ANOVA purposes is given. The accuracy of the approximations to the noncentral-F distribution is also discussed. The authors wish to thank Mr. Richárd Király for his preliminary work. The authors are grateful to the Editor and Associate Editor of STCO and the unknown reviewers for their helpful suggestions.     

The U.S. Health System and Immigration: An Institutional Interpretation1

We examine the institutions that comprise the U.S. health system and their relationship to a surging immigrant population. The clash between the system and this human flow originates in the large number of immigrants who are unauthorized, poor, and uninsured and, hence, unable to access a system largely based on ability to pay. Basic concepts from sociological theory are brought to bear on the analysis of this clash and its consequences. Data from a recently completed study of health institutions in three areas of the United States are used as an empirical basis to illustrate various aspects of this complex relation. Implications of our results for theory and future health policy are discussed.     

Children’s Strategies for Agency in Preschool

This article is based on an ethnographic study of children’s everyday life in Swedish preschools. The ethnography is used to explore children’s strategies for influencing, defending and constructing the social order of a preschool institution. The focus of our concern is on how the children, in their interactions with each other and with the preschool teachers, manage the collective regulation and how they negotiate their participation in collective activities. There is an inherent tension between free play and the high degree of routinised and collective activities within the preschool institution. The study shows that children are active in playing at the border, acting as if the institution is the children’s place. It also shows how they draw on different strategies as resources for managing the regulations, accounting for personal autonomy and negotiating the social order. In taking a child perspective and acknowledging children as active agents, it is possible to see how they influence and shape their everyday life in a preschool context. In addition, the article illustrates individual children’s strategic and pragmatic use of resources and in doing so contribute to their own childhood and thereby become part of a social and cultural construction process.     

Social Cognitive Predictors of the Career Goals of Korean American Students

Limited empirical study of the career development of Asian Americans in general and Korean Americans in particular has been conducted. The authors present the results of a theory‐based exploration of the career goals of Korean American university students in which ethnic identity, self‐efficacy, outcome expectations, and career interests were used to predict goal intentions for science and nonscience careers. Outcome expectations and career interests predicted a moderate amount of variance in science career goal intentions and a moderate to large amount of variance in nonscience career goal intentions. Korean American students' career goal development seems similar to that of American college students.     

A Preliminary Study on the Effectiveness of the Chinese Career Key Online

The Chinese Career Key (CCK) Online was studied for its effectiveness and user satisfaction. Study participants were 92 students at a public high school in Hong Kong. The research findings provide preliminary evidence of reliability, validity, and user satisfaction for the CCK Online. Limitations and implications for future studies and counseling practice across cultures are discussed.     

A framework for the comparison of maximum pseudo-likelihood and maximum likelihood estimation of exponential family random graph models

The statistical modeling of social network data is difficult due to the complex dependence structure of the tie variables. Statistical exponential families of distributions provide a flexible way to model such dependence. They enable the statistical characteristics of the network to be encapsulated within an exponential family random graph (ERG) model. For a long time, however, likelihood-based estimation was only feasible for ERG models assuming dyad independence. For more realistic and complex models inference has been based on the pseudo-likelihood. Recent advances in computational methods have made likelihood-based inference practical, and comparison of the different estimators possible.     

The roles of human capital and social capital in the economic integration of new arrivals from Mainland China to Hong Kong

Although it has been hypothesized in the literature that both human capital and social capital are important for the economic performance of new immigrants, few studies have examined these relationships empirically, especially in understudied populations such as Chinese populations. This study simultaneously examines the roles of human capital and social capital in the economic integration of new arrivals from Mainland China to Hong Kong, using a random sample of immigrants. In the early stage of immigration (less than 6 months after arrival), we find little support for the presumed positive effects of both human capital and social capital on employment status among new arrivals in Hong Kong. Follow-up studies are underway to investigate the dynamic relationship between social capital and economic integration in this group of new arrivals, and whether social capital, especially friendship networks, plays a more important role in the economic integration of new immigrants 1 or 2 years after arrival.     

Time and exclusion

Drawing on interviews with parents of children with complex disabilities in several school systems in a US state, this paper examines how temporal units such as the school day and school year and practices organized around artifacts like clocks and calendars work as ‘devices of temporal distanciation’ to separate children with disabilities from other children and exclude their families from critical relations with schools. The paper focuses on two kinds of effects: the ways differentiated timetables separate children and the ways constructing school time in bounded, discrete units limits the ability of parents and children to make key elements of their lives visible to the school.