A Bayesian Time Series Model of Multiple Structural Changes in Level,Trend, and Variance

We investigate whether seasonal-adjustment procedures are, at least approximately, linear data transformations. This question was initially addressed by Young and is important with respect to many issues including estimation of regression models with seasonally adjusted data. We focus on the X-11 program and rely on simulation evidence, involving linear unobserved component autoregressive integrated moving average models. We define a set of properties for the adequacy of a linear approximation to a seasonal-adjustment filter. These properties are examined through statistical tests. Next, we study the effect of X-11 seasonal adjustment on regression statistics assessing the statistical significance of the relationship between economic variables. Several empirical results involving economic data are also reported.     

A case–control study relating railroad worker mortality to diesel exhaust exposure using a threshold regression model

A case–control study of lung cancer mortality in U.S. railroad workers in jobs with and without diesel exhaust exposure is reanalyzed using a new threshold regression methodology. The study included 1256 workers who died of lung cancer and 2385 controls who died primarily of circulatory system diseases. Diesel exhaust exposure was assessed using railroad job history from the US Railroad Retirement Board and an industrial hygiene survey. Smoking habits were available from next-of-kin and potential asbestos exposure was assessed by job history review. The new analysis reassesses lung cancer mortality and examines circulatory system disease mortality. Jobs with regular exposure to diesel exhaust had a survival pattern characterized by an initial delay in mortality, followed by a rapid deterioration of health prior to death. The pattern is seen in subjects dying of lung cancer, circulatory system diseases, and other causes. The unique pattern is illustrated using a new type of Kaplan–Meier survival plot in which the time scale represents a measure of disease progression rather than calendar time. The disease progression scale accounts for a healthy-worker effect when describing the effects of cumulative exposures on mortality.     

Linking dichotomous segregation with multi-group segregation: Weighted segregation ratios in selected U.S. metropolitan areas

The U.S. residential landscape is increasingly multi-racial and multi-ethnic, giving rise to the question of how to compare dichotomous segregation among multiple groups living in the same area. To address the problem in the existing dichotomous approach, which offers no common basis for comparing dichotomous segregation among multiple groups, this paper develops a weighted segregation ratio approach based on Theil’s segregation index and its additive decomposability. This approach can be used to bridge information obtained from dichotomous segregation between specific groups (such as black-white and black-Hispanic), and dichotomous segregation between group and non-group (such as white-non-white and black-non-black) in previous studies. We apply both dichotomous and weighted segregation ratio approaches to 1990 and 2000 U.S. census data. Results are interpreted for five selected metropolitan areas as well as for the weighted national average. This new approach yields distinctive findings that portray the complicated process of residential segregation, including the increasing significance of Hispanic segregation and Asian segregation in the decade from 1990 to 2000.     

Engaging suffering: towards a mindful re-visioning of family therapy practice

The myth of problem-free living is easily identifiable in Western culture through its childhood fairy tales and modern love stories. Even if inadvertently, the field of mental health perpetuates this myth with the very concept of "mental health," which implies a state without suffering. Using mindfulness, Buddhists assume an alternative stance towards suffering: rather than eliminate it, they compassionately engage it. This article explores the potentials of mindfulness as an alternative approach to suffering within the context of marriage and family therapy. Family therapists can integrate mindfulness principles into their work to help clients shift how they relate to the unique forms of suffering that one encounters in intimate relationships, such as abuse, divorce, rejection, and loss.     

An Empirical Test of a Neo-Malthusian Theory of Fertility Change

Some neo-Malthusians regard fertility as being kept in check by scarcities and constraints and, conversely, as being raised by economic prosperity. Since out-migration to developed countries and the receipt of food aid from developed countries relax the constraints imposed by a country’s carrying capacity, both will have a positive effect on fertility rates in developing countries. Moreover, better economic prospects will also raise fertility, all other things equal. This article provides an empirical test of these hypotheses derived from a neo-Malthusian theory of fertility change. The results fail to confirm the theory and often contradict it.

Sexual identity distress, social support, and the health of gay, lesbian, and bisexual youth

Sex researchers and mental health clinicians have long recognized that the stigma surrounding homosexuality plays an important role in shaping the social psychological adjustment of gay, lesbian, and bisexual (g/l/b) people. In recent years, researchers have suggested that sexual identity- related distress may influence the physical health status of g/l/b people, primarily because of the ways these self-related feelings and beliefs impact patterns of health-related behavior. This study examines the influence of sexual identity distress and social support on g/l/b youth's drug and alcohol use, psychological distress, and risky sexual behavior. The data come from a services research demonstration program conducted at the Indiana Youth Group, Inc., a g/l/b youth development agency based in Indianapolis, Indiana. Results indicate that sexual identity distress is strongly associated with psychological distress, less frequent use of alcohol, and using fewer types of illegal drugs. Being out to more people in one's support network, however, attenuates the severity of youth's sexual identity-related distress. Youth who report more support ties to g/l/b people indicate engaging in more frequent risky sexual behavior. The implications of these findings for theories of g/l/b youth's sexual identity development are discussed.     

Efficient Heuristics for MRP Lot Sizing with Variable Production/Purchasing Costs*

Two heuristics based on branch and bound (B&B) are developed to solve closed-loop material requirements planning (MRP) lot-sizing problems that have general product structures and variable costs. A “look ahead method'’(LAM) heuristic allows for variable production/purchasing costs and uses a single-level B&B procedure to rapidly improve lower bound values; thus, LAM efficiently uses computer-storage capacity and allows solution of larger problems. The “total average modification'’(TAM) heuristic uses B&B, applied level by level, and modified setup and carrying costs to solve the variable production/purchasing costs MRP lot-sizing problem. LAM and TAM are tested on problems and compared to heuristics in the literature. TAM may be used to solve large MRP lot-sizing problems encountered in practice.