Batch sampling to improve power in a community trial. Experience from the Pawtucket Heart Health Program

Experiments involving large social units, such as schools, work sites, or whole cities, are commonly limited in statistical power because the number of randomized units is small, leaving few degrees of freedom for residual (between-unit) error. The authors describe a method for increasing residual degrees of freedom in a community experiment without substantially increasing cost or difficulty. In brief, they propose that the experimental units should be divided into random subsamples (batches). Batch sampling can improve statistical power if the community endpoint means are stable over time or if their temporal variation is comparable in period to the batch-sampling schedule. The authors demonstrate the theoretical advantages of the batch system and illustrate its use with data from the Pawtucket Heart Health Program, in which such a design was implemented.     

Art therapy as a modality for crisis intervention: Children express reactions to violence in their community

Ten days after the Symbionese Liberation Army's shoot out in Los Angeles in 1974, the Cedars-Sinai Medical Center, Department of Family Child Psychiatry, Thalians Community Mental Health Center, sent a crisis team of three psychotherapists to a school in the black community. The psychotherapists used an art therapy approach with a third grade classroom of 21 black children. The team's procedure helped the children ventilate their reactions to a frightening event which occurred in their neighborhood. This paper describes the art therapy techniques which were utilized, the children's vivid pictorial and verbal expressions accompanied by the psychological aspects of their responses.     

Bounding Optimal Expected Revenues for Assortment Optimization under Mixtures of Multinomial Logits

We consider assortment problems under a mixture of multinomial logit models. There is a fixed revenue associated with each product. There are multiple customer types. Customers of different types choose according to different multinomial logit models whose parameters depend on the type of the customer. The goal is to find a set of products to offer so as to maximize the expected revenue obtained over all customer types. This assortment problem under the multinomial logit model with multiple customer types is NP‐complete. Although there are heuristics to find good assortments, it is difficult to verify the optimality gap of the heuristics. In this study, motivated by the difficulty of finding optimal solutions and verifying the optimality gap of heuristics, we develop an approach to construct an upper bound on the optimal expected revenue. Our approach can quickly provide upper bounds and these upper bounds can be quite tight. In our computational experiments, over a large set of randomly generated problem instances, the upper bounds provided by our approach deviate from the optimal expected revenues by 0.15% on average and by less than one percent in the worst case. By using our upper bounds, we are able to verify the optimality gaps of a greedy heuristic accurately, even when optimal solutions are not available.     

The effect of disability on the net worth of elderly people

As demographic shifts make the Social Security program financially vulnerable, the responsibility for income security in old age will shift from the government to elderly people. In this changing environment, the accumulation of wealth will be a crucial issue because wealth holders can draw income from assets, which can supplement retirement income. Thus, wealth (or net worth) is a proximate indicator of economic well-being of the elderly. This article presents the findings of a study of the net worth of elderly people with disabilities. The major findings were that a smaller proportion of elderly people with disabilities has assets of any type compared with elderly people with no disability; the dollar value of each type of asset is smaller among elderly people with disabilities than among elderly people with no disability; and the net worth of people with disabilities is smaller than that of elderly people with no disability even after other variables were controlled.     

Pointing to Visible and Invisible Targets

We investigated how the visibility of targets influenced the type of point used to provide directions. In Study 1, we asked 605 passersby in three localities for directions to well-known local landmarks. When that landmark was in plain view behind the requester, most respondents pointed with their index fingers, and few respondents pointed more than once. In contrast, when the landmark was not in view, respondents pointed initially with their index fingers, but often elaborated with a whole-hand point. In Study 2, we covertly filmed the responses from 157 passersby we approached for directions, capturing both verbal and gestural responses. As in Study 1, few respondents produced more than one gesture when the target was in plain view and initial points were most likely to be index finger points. Thus, in a Western geographical context in which pointing with the index finger is the dominant form of pointing, a slight change in circumstances elicited a preference for pointing with the whole hand when it was the second or third manual gesture in a sequence.     

Deconstructing Immigrant Illegality: A Mixed-Methods Investigation of Stress and Health Among Undocumented College Students

Research has established that being undocumented is a risk factor for mental and physical health conditions. Much of this work emphasizes undocumented immigrants’ chronic stress, yet key questions about pathways to health remain. The mere state of being undocumented is viewed as a general stressor, without considering actual levels of stress or identifying dimensions of documentation status that contribute to overall stress levels. Drawing on surveys and interviews with undocumented students at the University of California, we uncover the everyday manifestations of four dimensions of immigrant “illegality”: academic concerns, future concerns, financial concerns, and deportation concerns, and their association with reported stress levels and self-rated health. Survey data establish undocumented students’ high levels of stress and poorer health, in comparison to previous research on other national samples. In a structural equation model, we found academic and future concerns to be significantly associated with higher stress, which was in turn, associated with poorer self-rated health. Financial concerns were not associated with higher perceived stress but were directly associated with poorer self-rated health. Notably, deportation concerns did not have any significant independent associations with stress or health. We use our qualitative data to identify specific stressors embedded within these four dimensions. Our findings inform understandings of the health risks arising from documentation status.     

Childhood family structure and young adult behaviors

This paper examines a wide variety of forms, and full histories, of family structure to test existing theories of family influences and identify needs for new theories. The focus is on links between childhood family structure and both completed schooling and risk of a nonmarital birth. Using a 27-year span of panel (PSID) data for U.S. children, we find that: (a) change is stressful, (b) timing during childhood is relevant, (c) adults other than parents are important, and (d) two more recently studied family structures (mother-with-grandparent(s) and mother-with-stepfather) do not fit the molds of existing theories. The findings suggest that new theories should consider allocation of resources and reasons people group into family structures. Received: 11 September 1998/Accepted: 27 March 2000