Teaching Elementary Bayesian Statistics with Real Applications in Science

University courses in elementary statistics are usually taught from a frequentist perspective. In this paper I suggest how such courses can be taught using a Bayesian approach, and I indicate why beginning students are well served by a Bayesian course. A principal focus of any good elementary course is the application of statistics to real and important scientific problems. The Bayesian approach fits neatly with a scientific focus. Bayesians take a larger view, and one not limited to data analysis. In particular, the Bayesian approach is subjective, and requires assessing prior probabilities. This requirement forces users to relate current experimental evidence to other available information–-including previous experiments of a related nature, where “related” is judged subjectively. I discuss difficulties faced by instructors and students in elementary Bayesian courses, and provide a sample syllabus for an elementary Bayesian course.     

Contraception,attitude-practice,and fertility differentials among US Hispanic,African–American and white women

Hispanic fertility (primarily among nationals from Mexico, Central and South America in the US) is higher today than it is in Mexico and the other nations of origin (Frank and Heuveline 2005). It persists into the second and third generations, with only moderate signs of declining to replacement. Meanwhile, the fertility rates of African–Americans, American Indians Cubans, and Puerto Ricans have all declined to replacement, only slightly above the non-Hispanic white population. This study attempts to clarify the question why African–American fertility has declined to replacement, but Hispanic fertility has not. The data used are from Cycle 6 of the National Survey of Family Growth (NSFG) of 2002. Differences in physiological or marital-status factors are found not to explain these fertility differences; however, there are significant differences in the practice of contraception during early childbearing years. Slightly less effective methods if contraception is used, and less recourse to abortion if a pregnancy is undesired, all imply higher fertility for Hispanic women. Underlying contraceptive behaviour are sets of attitudes and motives that favour, permit, or seek childbearing. A much higher percentage of Hispanic than African–American women report that they wanted their last birth and intend to have another in the future. Hispanic women of all socio-economic statuses are considerably more pronatal in their attitudes, particularly with respect to the births of first and second children.     

Use of Quality-Adjusted Life Year Weights with Dose-Response Models for Public Health Decisions: A Case Study of the Risks and Benefits of Fish Consumption

Risks associated with toxicants in food are often controlled by exposure reduction. When exposure recommendations are developed for foods with both harmful and beneficial qualities, however, they must balance the associated risks and benefits to maximize public health. Although quantitative methods are commonly used to evaluate health risks, such methods have not been generally applied to evaluating the health benefits associated with environmental exposures. A quantitative method for risk-benefit analysis is presented that allows for consideration of diverse health endpoints that differ in their impact (i.e., duration and severity) using dose-response modeling weighted by quality-adjusted life years saved. To demonstrate the usefulness of this method, the risks and benefits of fish consumption are evaluated using a single health risk and health benefit endpoint. Benefits are defined as the decrease in myocardial infarction mortality resulting from fish consumption, and risks are defined as the increase in neurodevelopmental delay (i.e., talking) resulting from prenatal methylmercury exposure. Fish consumption rates are based on information from Washington State. Using the proposed framework, the net health impact of eating fish is estimated in either a whole population or a population consisting of women of childbearing age and their children. It is demonstrated that across a range of fish methylmercury concentrations (0-1 ppm) and intake levels (0-25 g/day), individuals would have to weight the neurodevelopmental effects 6 times more (in the whole population) or 250 times less (among women of child-bearing age and their children) than the myocardial infarction benefits in order to be ambivalent about whether or not to consume fish. These methods can be generalized to evaluate the merits of other public health and risk management programs that involve trade-offs between risks and benefits.     

Sequential analysis of 3m supersaturated factorial experiments

In this paper, designs that allow for the estimation of all main effects, and the detection and estimation of significant interactions in fewer runs than used in traditional approaches are examined. Specifically, a method for sequentially analyzing data from 3m fractional factorial experiments is presented. The procedure is illustrated through two examples.     

When Change Hits the Fan

This case study is based on an actual situation that has been disguised and has had some hypothetical content added. It addresses several problems that may be encountered as an agency struggles with its evolution from a hierarchical bureaucratic organizational structure to an egalitarian consensus model of management. Issues include resistance to change, difficulties with the modification of staff and board roles and responsibilities, and the resultant interpersonal conflict.     

An examination of population changes in Alabama's black belt counties: 1960–1970 and 1970–1980

Population changes in 11 Alabama Black Belt counties are examined by comparing annual average birth, death, and migration rates during the 1960s with those of the 1970s. The specific focus of the study is migration patterns among the nonwhite segment of the population. Data from the 1980 and earlier censuses are utilized, along with birth and death data from Alabama vital statistics reports. Average annual migration rates for each of the two decades are derived. The results indicate that net migration losses among nonwhites declined substantially during the 1970s compared with the 1960s and that in two Black. Belt counties there was a reversal from heavy net losses to moderate net gains. Whites, on a county‐to‐county basis, however, were generally characterized by significantly higher rates of loss during the 1970s than in the 1960s. The substantial reduction in outmigration rates among nonwhites is tentatively attributed to political and economic advances coupled with increased employment opportunities in nonagricultural occupations.