The Effect of Veteran Status on Mortality among Older Americans and its Pathways

This research examines excess mortality among American veterans age 70 years or older during a two-to-three year interval from 1993/94 to the end of 1995. Using a structural hazard rate model, we analyzed data on a sample of respondents age 70 or over from the Survey of Asset and Health Dynamics among the Oldest Old (AHEAD). We found that at age 70, older veterans have a slightly higher death rate than their nonveteran counterparts, implying a mortality crossover right before this age. Such excess mortality among veterans increases considerably with age, when other factors are held equal. The direct and indirect effects of veteran status on mortality by means of physical and mental health mostly perform in opposite directions, and such effects vary greatly in magnitude and direction as a function of age. The intervening effects of physical and mental health status decrease substantially with increasing age. Many of the mechanisms inherent in the excess mortality among older veterans are not captured by variations in their health status, especially among the oldest-old. A more extensive study on this topic is urgently needed.     

The role of public health improvements in health advances: The twentieth-century United States

Mortality rates in the United States fell more rapidly during the late nineteenth and early twentieth centuries than in any other period in American history. This decline coincided with an epidemiological transition and the disappearance of a mortality "penalty" associated with living in urban areas. There is little empirical evidence and much unresolved debate about what caused these improvements, however. In this article, we report the causal influence of clean water technologies--filtration and chlorination--on mortality in major cities during the early twentieth century. Plausibly exogenous variation in the timing and location of technology adoption was used to identify these effects, and the validity of this identifying assumption is examined in detail. We found that clean water was responsible for nearly half the total mortality reduction in major cities, three quarters of the infant mortality reduction, and nearly two thirds of the child mortality reduction. Rough calculations suggest that the social rate of return to these technologies was greater than 23 to 1, with a cost per person-year saved by clean water of about dollar 500 in 2003 dollars. Implications for developing countries are briefly considered.     

Online personal ads: community and sex, virtually

This study samples 200 personal advertisements from the online gay and lesbian global Web portal PlanetOut. This data, along with survey responses completed by advertisers included in the sample, are used to frame a discussion on the use of online gay and lesbian spaces and communities. Despite interacting in a global space, data showed that advertisers remained aware of their local identities. Differences between advertisers were most notable between gender and whether they logged on in a small or large town. Advertisers were interested in interacting locally, eager to move from online to offline communication, often-times not overly concerned with maintaining anonymity, and not interested in toying with multiple identities. Users of PlanetOut personals largely did not consider themselves part of a virtual gay and lesbian community even when they recognized the existence of a local geographically-based gay and lesbian community. However, the dynamic nature of online personal advertisements did allow for a new type of interactive advertisement that does differ from previous print forums.     

The robustness and optimality of response surface designs

Recent work on extended optimality criteria for robust designs is applied to response surface problems. Methods of calculation are described and the criteria illustrated with several examples. The extended criteria discriminate among designs equivalent by other criteria.     

The demand to initiate medical care: A morbidity specific analysis

The dependence of the one year probability of utilizing preventive services and the one year probability of utilizing visits for acute micro-organism disease in the Kaiser-Oregon Prepaid Medical Care System on ten (10) explanatory factors has been investigated using a multiple logistic function analysis.Our results demonstrate the importance of disaggregating the population and the type of medical care when investigating the determinants of utilizing service. This is especially important for understanding the underlying structure of medical care utilization decisions.The study also illustrates a potentially fruitful application of the multivariate logistic analysis to the fields of health care planning and policy analysis. The use of specific types of medical care in the short-term is probabilistic and depends on many factors. For most groups, the multivariate logistic approach produces an analysis reasonably consistent with the actual data.Further research is needed to test the predictive ability of these types of utilization models and to investigate the determinants of other morbidity specific types of medical care utilization. The problem will then be to develop a model of the quantity of alternative types of services utilized-conditioned on the number of persons initiating service for alternative health reasons.     

Some aspects of modern population mathematics

The purpose of this paper is to survey a number of the technical tools and models that have found use in the study of human and other populations, and to indicate some problems of current interest. These tools and models are varied: integral equations, nonlinear oscillations, differential geometry, dynamical systems, nonlinear operations, bifurcation theory, semigroup theory, martingale theory, Markov processes, diffusion processes, branching processes, ergodic theory, prediction theory and state-space models. A fairly extensive bibliography is provided. Also an Appendix has been added describing the analysis of a classical entomological data set.