Negative binomial control limits for count data with extra‐Poisson variation

Traditional techniques for calculating control limits for processes with discrete responses are based on the Poisson distribution. However, for many processes, the assumption of a Poisson distribution is violated. In such cases, use of traditional Poisson control limits may result in an inflated risk of Type I error. The negative binomial distribution is a natural extension of the Poisson distribution and allows for over‐dispersion relative to the Poisson distribution. A simple approach to calculating exact and approximate control limits for count data based on the negative binomial distribution is described. The approach is illustrated by application to water bacteria count data taken from a water purification system. Copyright © 2003 John Wiley & Sons, Ltd.     

Welfare benefits,economic opportunities,and out-of-wedlock births among black teenage girls

This article presents a model of teenage out-of-wedlock births that incorporates the effects of both welfare and nonwelfare economic opportunities. We construct measures of the likely "medium-run" income available to a teenage girl in the event of an out-of-wedlock birth and in the absence of a birth and then estimate a logit model to determine their importance in influencing fertility behavior. The model is estimated with data from the Panel Study of Income Dynamics on nearly 900 black teenagers. We find weak and statistically insignificant positive effects of Aid to Families With Dependent Children (AFDC) benefit levels and stronger and significant negative effects of economic opportunities on the probability of AFDC-related out-of-wedlock teen births.     

What are the economic consequences of divorce?

Our analysis suggests that Weitzman's finding concerning the precipitous decline in the economic status of women following divorce is likely to be incorrect. Her findings not only imply improbably large changes in income but are also inconsistent with the information she reports on changes in income and in income per capita. Corrected estimates suggest a decline in economic status of about one-third, rather than the widely cited 73 percent figure. It remains the case that the economic status of men and women diverge substantially in the years after divorce. That difference, however, is not nearly as dramatic as suggested by Weitzman's findings.     

Regional Variations in the Realignment of American Politics, 1944–2004*

Objective. Perennial questions in electoral studies are what constitutes realignment, and when and where do realignments occur? Using the concepts of critical and secular realignments as a framework, we model change in the end product of realignment, election outcomes. We test for secular and critical changes in partisan strength across six geographic regions of the United States, focusing on office‐holding data at both the federal and state legislative level. Methods. Using an interrupted time‐series model, we examine evidence for secular realignment and posit five critical interventions that have affected American politics since World War II. Results. Our findings suggest that there are elements of both critical and secular realignments at work with different patterns in each region, and that different regions have been affected by a variety of elections associated with critical events since 1944. Conclusions. The collapse of Republican hegemony in the Northeast and Pacific West has gone largely unnoticed, buried in the intense examination of the growth of the Republican Party in the American South. The 1994 election is the most prominent in terms of its impact on seat holding by the parties at both the state and national level, and constitutes a realigning election.     

Service Learning and Developmental Education: The Need for an Applied Theory of Role-Taking and Reflection

This article examines service learning through the lens of cognitive-developmental psychology and developmental education. Recent interest in service learning as a means of encouraging further learning and growth is commendable; however, the goals need to be linked to relevant research and theory. Such theory is lacking. The theories of Kohlberg, Hunt, and Loevinger, as well as recent research on social role-taking and guided reflection interventions are reviewed. The goal is to build a developmentally based theory of service learning that provides conditions (e.g., action, reflection, balance, support and challenge, continuity) to promote guiding programs and to explain how persons construct meaning as they engage in problem solving and reflection on complex new roles and encounter social-ethical issues. Implications for practitioners and future research are discussed.