Permanent Income,Current Income,and Consumption

This article reexamines the consistency of the permanent-income hypothesis with aggregate postwar U.S. data. The permanent-income hypothesis is nested within a more general model in which a fraction of income accrues to individuals who consume their current income rather than their permanent income. This fraction is estimated to be about 50%, indicating a substantial departure from the permanent-income hypothesis. Our results cannot be easily explained by time aggregation or small-sample bias, by changes in the real interest rate, or by nonseparabilities in the utility function of consumers.     

Posterior probability estimators in classification simulations

Class specific stratified posterior probability estimators of misclassification probabilities in discriminant analysis simulations are introduced. These estimators afford a significant variance reduction over the usual count estimators. Sufficient conditions for a variance reduction are given. The stratified posterior probability estimator is generalized to other class specific expectations.     

Tables of critical values for two group interim analyses

Tables of critical values are given, which can be used to execute interim analyses in clinical trials involving two groups when the joint distribution of the test statistics can be approximated by a multivariate normal distribution. Critical values are given for both the one and two interim analyses cases for a variety of partitions of α and correlation structures. Results of power calculations are presented, which reflect the effects of both the correlation structure and partitions of α.Several examples are given, which illustrate how to apply the tables to a variety of experiments     

Investigation of disease-free survival as a surrogate endpoint for survival in cancer clinical trials

A stochastic model wiuh exponential components is used to describe our data collected from a phase III cancer clinical trial. Criteria which guarantee that disease-free survival (DFS) can be used as a surrogate for overall survival are explored under this model. We examine several colorectal adjuvant clinical trials and find that these conditions are not satisfied. The relationship between the hazard ratio of DFS for an active treatment versus a control treatment and the cumulative hazard ratio of survival for the same two treatments is then explored. An almost linear relationship is found such that a hazard ratio for DFS of less than a threshold R corresponds to a non-null treatment effect on survival The threshold value R is determined for our colorectal adjuvant trial data. Based on this relationship, a one-sided test of equal hazard rate of survival is equivalent to a test of hazard ratio of DFS small than R This approach assumes that recurrence information is unbiasedly and accurately assessed; an assumpion which is sometimes difficult to ensure for multicenter clinical trials, particularly for interim analyses.     

Spatial heterogeneity in drinking water sources in the Greater Accra Metropolitan Area (GAMA), Ghana

Population and Environment - Universal access to safe drinking water is essential to population health and well-being, as recognized in the Sustainable Development Goals (SDG). To develop targeted...     

Marital Disruption and Health Insurance

Despite the high levels of marital disruption in the United States and the fact that a significant portion of health insurance coverage for those less than age 65 is based on family membership, surprisingly little research is available on the consequences of marital disruption for the health insurance coverage of men, women, and children. We address this shortfall by examining patterns of coverage surrounding marital disruption for men, women, and children, further subset by educational level. Using the 1996, 2001, and 2004 panels of the Survey of Income and Program Participation (SIPP), we find large differences in health insurance coverage across marital status groups in the cross-section. In longitudinal analyses that focus on within-person change, we find small overall coverage changes but large changes in type of coverage following marital disruption. Both men and women show increases in private coverage in their own names, but offsetting decreases in dependent coverage tend to be larger. One surprising result is that dependent coverage for children also declines after marital dissolution, even though children are still likely to be eligible for that coverage. Children and (to a lesser extent) women show increases in public coverage around the time of divorce or separation. We also find that these patterns differ by education. The most vulnerable group appears to be lower-educated women with children because the increases in private, own-name, and public insurance are not large enough to offset the large decrease in dependent coverage. As the United States implements federal health reform, it is critical that we understand the ways in which life course events—specifically, marital disruption—shape the dynamic patterns of coverage.     

The effect of probabilistic demands on the structure of cost functions

Firms that provide capacity to meet randomly fluctuating demand typically will not be producing on the efficient frontier of their production possibilities sets. Consequently, the standard dual theory of cost and production is inapplicable. This article provides an alternative that leaves most of the theory intact provided that firms are viewed as producing the probability of providing service rather than an explicit produced output. As an application we show that for a telecommunications firm facing a network externality it is quite possible to find something that looks like negative marginal cost.The opinions expressed in this paper are those of the author alone and do not necessarily represent the opinions of GTE or any of its subsidiaries. I'd like to thank Kip Viscusi, Dave Salant, Glenn Woroch, and Larry Cole for various comments. To Roger Tobin, my coauthor on other parts of this study, I give a particular thanks.     

On the axiomatisation of subjective probabilities

This paper essentially makes two remarks that are pertinent to many of the axiomatisations of subjective probability. First, the auxiliary experiment used to quantify qualitative feelings of relative likelihood is essentially distinct from the field of events of actual interest and may be kept so in the axiomatisation. Second, all theories of subjective probability agree that beliefs are conditional on the present state of knowledge and on the present mood and attitude of the individual concerned. As the individual moves through time this conditioning set, his knowledge and psychological state, change. This ever present change has implications for the conditions under which Bayes' Theorem may be invoked to prescribe how the individual should rationally update his beliefs in the light of a particular observation.     

Social Psychological Factors in Lifestyle Change and Their Relevance to Policy

Crises in obesity and changes in the environment illustrate the need to change problematic behaviors and lifestyles in large segments of the population. This article uses social psychological theory and research to understand methods for facilitating lifestyle change. A basic assumption in the social psychological perspective is that the environment and the person interact to determine behavior. Both factors are important for understanding "upstream" and "downstream" approaches to lifestyle change ( McKinlay, 1993 ; Verplanken & Wood, 2006 ) and consideration of one factor without the other may be disastrous. We review evidence from within and outside of the health context to illustrate the upstream and downstream approaches and then describe implications for public policy and intervention. The evidence and recommendations encompass a wide range of behaviors, ranging from speeding and intoxicated driving to eating an unhealthy diet and energy conservation. When armed with the relevant social psychological theory and evidence, lifestyle change campaigns are likely to be successful.     

Willingness to pay for mortality risk reductions: Does latency matter?

Using results from two contingent valuation surveys conducted in Canada and the U.S., we explore the effect of a latency period on willingness to pay (WTP) for reduced mortality risk using a structural model. We find that delaying the time at which the risk reduction occurs by 10 to 30 years reduces WTP by more than 60% for respondents in both samples aged 40 to 60 years. The implicit discount rates are equal to 3.0–8.6% for Canada and 1.3–5.6% for the U.S. JEL Classification Q51 · Q58 The findings, interpretations and conclusions expressed in this paper are entirely those of the authors. They do not necessarily represent the views of the USEPA or of the World Bank, its Executive Directors or the countries they represent.