Direct and Indirect Causal Effects via Potential Outcomes*

Abstract. The use of the concept of ‘direct’ versus ‘indirect’ causal effects is common, not only in statistics but also in many areas of social and economic sciences. The related terms of ‘biomarkers’ and ‘surrogates’ are common in pharmacological and biomedical sciences. Sometimes this concept is represented by graphical displays of various kinds. The view here is that there is a great deal of imprecise discussion surrounding this topic and, moreover, that the most straightforward way to clarify the situation is by using potential outcomes to define causal effects. In particular, I suggest that the use of principal stratification is key to understanding the meaning of direct and indirect causal effects. A current study of anthrax vaccine will be used to illustrate ideas.     

Rural/Urban Differences in Child Growth and Survival in Bolivia

Abstract Using data from a national survey in Bolivia and from a regional sample of poor communities in two regions of Bolivia, we model the effects of community conditions, household characteristics, and social relations on child health as measured by child mortality and stunted growth. Based on national data, children in rural areas are twice as likely to die before the age of two than are children in large cities, and about one‐third of the children in rural areas are stunted. Including measures of community, household, and maternal characteristics accounts for at least two‐thirds of the urban/rural difference in child health. We conclude that expansion of health services, improvements in household and community sanitation, and socioeco‐nomic development are all needed to overcome the rural disadvantage in child health.     

The Exclusion of Disabled People from Positions of Power in British Voluntary Organisations

Disabled people are excluded in various ways from a wide range of social privileges, activities and institutions. Voluntary and charitable organisations promote themselves as champions of disabled people in their struggle for access to the ordinary choices and opportunities of everyday life. This paper reports the findings of an empirical study which demonstrate that in voluntary agencies governed by able-bodied people, disabled people are excluded from positions of power and influence, and they experience the same sorts of barriers and constraints as those with which they are confronted in the wider world. Furthermore, the development of agencies governed by disabled people themselves is constrained by their lack of access to money, staff and other resources.     

The theoretical and empirical structure of general well-being

A comprehensive set of variables that have been supported as contributing to overall health and general well-being were analyzed to determine their simple structure using factor analysis and their relative contribution using Pearson correlation. The contributors to general well-being had been theoretically grouped into: emotions, beliefs, temperaments, behaviors, sittuations, experiences and health. The empirical factor structure was compared with the theoretical structure used to develop the variables. Stability was investigated by comparing results with those of another geographically separated group. All subjects were normally functioning working adults. The results demonstrated the feasibility and potential usefulness of using self-report questionnaires with multivariate procedures to measure components of the global general well-being concept.     

A screening system for tardive dyskinesia: development and implementation.

1. Most diagnosed cases of tardive dyskinesia (TD) are mildly inconvenient to the patient, but some can be severe or life-threatening. The primary goal of intervention should be early identification of abnormal movements related to TD and the prescribing of an appropriate medication regimen. 2. Unless specific training occurs and a specific monitoring system is in place, TD movements may be missed. However, not all movements are necessarily related to TD. 3. Although screening and monitoring are valuable, nothing is more important than prevention. New medications must be developed that do not carry the risk of TD, and other approaches to treat TD must be developed.     

The Effects of ROTC Program Participation on Socioeconomic Status and Life Satisfaction*

Using mail survey data based on a stratified systematic sample [N = 686] of 1983–1988 graduates of a medium-sized state university, this research evaluates whether ROTC program participation constitutes an independent source of human capital in civilian labor markets by comparing postgraduate earnings (annual income), prestige and authority, and life satisfaction of ROTC program participants with those of nonparticipants. The results revealed no statistically significant ROTC program participation effects, independent of subsequent military status. ROTC program participation paid off in terms of occupational prestige and authority for those on active duty, but not for those in national guard or reserve units. Neither ROTC participation nor current military status affected income or life satisfaction levels.     

Recurrent pain in college students.

The authors investigated the prevalence of recurrent pain in a college student sample. Of the 1,564 students surveyed, 467 (29%) indicated that they had experienced recurrent pain at an intensity that was mostly in the mild-to-moderate range. Students who reported having recurrent pain were significantly older and more depressed than students who did not indicate they suffered from recurrent pain. Pain intensity was positively correlated (r = .14) with depression among the students who reported having recurrent pain. Implications of the findings for future research, treatment, and health promotion efforts are discussed.     

城市可持续发展中的文化指标

本文为第三届“文化与城市可持续发展”国际会议的主题发言。本文介绍了会议背景 ,论述了文化及其与可持续发展的关系 ,都市化进程及其发展方向等问题 ,并着重阐述了本次会议的主题即“城市可持续发展中的文化指标” ,确立了本次会议的总体基调和基本政策     

What to Do at Low Doses: A Bounding Approach for Economic Analysis

To quantify the health benefits of environmental policies, economists generally require estimates of the reduced probability of illness or death. For policies that reduce exposure to carcinogenic substances, these estimates traditionally have been obtained through the linear extrapolation of experimental dose-response data to low-exposure scenarios as described in the U.S. Environmental Protection Agency's Guidelines for Carcinogen Risk Assessment (1986). In response to evolving scientific knowledge, EPA proposed revisions to the guidelines in 1996. Under the proposed revisions, dose-response relationships would not be estimated for carcinogens thought to exhibit nonlinear modes of action. Such a change in cancer-risk assessment methods and outputs will likely have serious consequences for how benefit-cost analyses of policies aimed at reducing cancer risks are conducted. Any tendency for reduced quantification of effects in environmental risk assessments, such as those contemplated in the revisions to EPA's cancer-risk assessment guidelines, impedes the ability of economic analysts to respond to increasing calls for benefit-cost analysis. This article examines the implications for benefit-cost analysis of carcinogenic exposures of the proposed changes to the 1986 Guidelines and proposes an approach for bounding dose-response relationships when no biologically based models are available. In spite of the more limited quantitative information provided in a carcinogen risk assessment under the proposed revisions to the guidelines, we argue that reasonable bounds on dose-response relationships can be estimated for low-level exposures to nonlinear carcinogens. This approach yields estimates of reduced illness for use in a benefit-cost analysis while incorporating evidence of nonlinearities in the dose-response relationship. As an illustration, the bounding approach is applied to the case of chloroform exposure.