An Enforceable Indoor Air Quality Standard for Environmental Tobacco Smoke in the Workplace1

Environmental tobacco smoke (ETS)has recently been determined by U.S. environmental and occupational health authorities to be a human carcinogen. We develop a model which permits using atmospheric nicotine measurements to estimate nonsmokers’ETS lung cancer risks in individual workplaces for the first time. We estimate that during the 1980s, the U.S. nonsmoking adult population's median nicotine lung exposure (homes and workplaces combined)was 143 micrograms (μg)of nicotine daily, and that most-exposed adult nonsmokers inhaled 1430 μg/day. These exposure estimates are validated by pharmacokinetic modeling which yields the corresponding steady-state dose of the nicotine metabolite, cotinine. For U.S. adult nonsmokers of working age, we estimate median cotinine values of about 1.0 nanogram per milliliter (ng/ml)in plasma, and 6.2 ng/ml in urine; for most-exposed nonsmokers, we estimate cotinine concentrations of about 10 ng/ml in plasma and 62 ng/ml in urine. These values are consistent to within 15% of the cotinine values observed in contemporaneous clinical epidemiological studies. Corresponding median risk from ETS exposure in U.S. nonsmokers during the 1980s is estimated at about two lung cancer deaths (LCDs)per 1000 at risk, and for most-exposed nonsmokers, about two LCDs per 100. Risks abroad appear similar. Modeling of the lung cancer mortality risk from passive smoking suggests that de minimis [i.e., “acceptable” (10^-6)], risk occurs at an 8-hr time-weighted-average exposure concentration of 7.5 nanograms of ETS nicotine per cubic meter of workplace air for a working lifetime of 40 years. This model is based upon a linear exposure-response relationship validated by physical, clinical, and epidemiological data. From available data, it appears that workplaces without effective smoking policies considerably exceed this de minimis risk standard. For a substantial fraction of the 59 million nonsmoking workers in the U.S., current workplace exposure to ETS also appears to pose risks exceeding the de manifestos risk level above which carcinogens are strictly regulated by the federal government.     

The effect of public policies on recent Swedish fertility behavior

In the literature the recent upsurge in period birth rates is seen as evidence of a pronatalist effect of Sweden's extensive social insurance programs. Yet, these explanations can not account for the downturn in birth rates in the 1970s, the delay in childbearing, and the constancy of cohort birth rates which characterize recent Swedish fertility behavior. To summarize the effect of Sweden's economic and policy environment on the observed fertility patterns, I use a neoclassical economic framework to develop the shadow price of fertility. Although strong simplifying assumptions are imposed, the estimated price series exhibit a negative relationship with period fertility rates and the change in the estimated relative prices of fertility over the life cycle lend modest support for the delayed childbearing.The first draft of this paper was written while I was a National Fellow at the Hoover Institution. The research was supported by grants number HD-19226 and HD-28685 from the National Institute of Child Health and Development. I thank Glen Cain, John Kerman, Tom MaCurdy, Duncan Thomas, Michael Tilkin, and seminar participants at University of Illinois, Hoover Institution, and University of Wisconsin for useful comments.     

Understanding the etiology of child abuse: A preliminary typology of cases

This paper examines various conceptual approaches to the etiology of child abuse and reports the results of an original study. Data on 99 families with children who were court adjudicated as having suffered non-accidental trauma were analyzed by means of a cluster analysis (hierarchical nearest-neighbor clustering). Four empirically-derived clusters of family/case attributes are described and then discussed as representing separate etiologies of child abuse. The implications of this typology are also discussed as they relate to clinical practice and social policy.     

Productivity indices and survival rate estimates from MAPS,a continent-wide programme of constant-effort mist-netting in North America

The Monitoring Avian Productivity and Survivorship (MAPS) programme is a cooperative effort to provide annual regional indices of adult population size and post-fledging productivity and estimates of adult survival rates from data pooled from a network of constant-effort mist-netting stations across North America. This paper provides an overview of the field and analytical methods currently employed by MAPS, a discussion of the assumptions underlying the use of these techniques, and a discussion of the validity of some of these assumptions based on data gathered during the first 5 years (1989-1993) of the programme, during which time it grew from 17 to 227 stations. Ageand species-specific differences in dispersal characteristics are important factors affecting the usefulness of the indices of adult population size and productivity derived from MAPS data. The presence of transients, heterogeneous capture probabilities among stations, and the large sample sizes required by models to deal effectively with these two considerations are important factors affecting the accuracy and precision of survival rate estimates derived from MAPS data. Important results from the first 5 years of MAPS are: (1) indices of adult population size derived from MAPS mist-netting data correlated well with analogous indices derived from point-count data collected at MAPS stations; (2) annual changes in productivity indices generated by MAPS were similar to analogous changes documented by direct nest monitoring and were generally as expected when compared to annual changes in weather during the breeding season; and (3) a model using between-year recaptures in Cormack-Jolly-Seber (CJS) mark-recapture analyses to estimate the proportion of residents among unmarked birds was found, for most tropical-wintering species sampled, to provide a better fit with the available data and more realistic and precise estimates of annual survival rates of resident birds than did standard CJS mark-recapture analyses. A detailed review of the statistical characteristics of MAPS data and a thorough evaluation of the field and analytical methods used in the MAPS programme are currently under way.     

The Emerging Migration State1

Since 1945, immigration in the core industrial democracies has been increasing. The rise in immigration is a function of market forces (demand‐pull and supply‐push) and kinship networks, which reduce the transaction costs of moving from one society to another. These economic and sociological forces are the necessary conditions for migration to occur, but the sufficient conditions are legal and political. States must be willing to accept immigration and to grant rights to outsiders. How then do states regulate migration in the face of economic forces that push them toward greater openness, while security concerns and powerful political forces push them toward closure? States are trapped in a “liberal” paradox — in order to maintain a competitive advantage, governments must keep their economies and societies open to trade, investment, and migration. But unlike goods, capital, and services, the movement of people involves greater political risks. In both Europe and North America, rights are the key to regulating migration as states strive to fulfill three key functions: maintaining security; building trade and investment regimes; and regulating migration. The garrison state was linked with the trading state in the eighteenth and nineteenth centuries. The twentieth and twenty‐first centuries have seen the emergence of the migration state, where regulation of international migration is as important as providing for the security of the state and the economic well being of the citizenry.     

Factors influencing wagers in simulated Blackjack

To understand some of the deviations from recommended optimal play in Blackjack, gamblers were considered to be decision makers who used decision rules to predict outcomes. The size of their wagers were used as an index of the confidence of these predictions. If this were the case, players' decisions would be affected by time pressure, short-term probability of winning, and their perceived control of outcomes. Players' wagering on a simulated game of Blackjack was examined to assess the feasibility of this approach. The computer simulation of Blackjack used simplified rules (no splitting, doubling down, insurance, etc.), and the probability of winning was controlled by the computer. Subjects could either choose whether they were dealt extra cards, or could bet upon another player. The other player was a computer algorithm that sat upon a total of fifteen. To examine effects of time pressure upon confidence of judgments, the time allowed to place a bet, and to choose extra cards, was manipulated. Twelve subjects played 20 hands under each of the experimental conditions. The mean amounts wagered, and players' choice of cards were both examined. The results suggested that deviations from optimal play can in part be understood in terms of players' decision processes, that are influenced by the time available to make a decision, the short-term probability of winning, and perceived control of outcomes; each factor may potentiate the effects of the others.The authors would like to acknowledge the assistance of Carl Waterman III, for his help with the graphics and timing routines used in the Blackjack program.     

An analytic method for randomized trials with informative censoring: Part II

Consider a randomized trial in which time to the occurrence of a particular disease, say pneumocystic pneumonia in an AIDS trial or breast cancer in a mammographic screening trial, is the failure time of primary interest. Suppose that time to disease is subject to informative censoring by the minimum of time to death, loss to and end of follow-up. In such a trial, the potential censoring time is observed for all study subjects, including failures. In the presence of informative censoring, it is not possible to consistently estimate the effect of treatment on time to disease without imposing additional non-identifiable assumptions. Robins (1995) specified two non-identifiable assumptions that allow one to test for and estimate an effect of treatment on time to disease in the presence of informative censoring. The goal of this paper is to provide a class of consistent and reasonably efficient semiparametric tests and estimators for the treatment effect under these assumptions. The tests in our class, like standard weighted-log-rank tests, are asymptotically distribution-free -level tests under the null hypothesis of no causal effect of treatment on time to disease whenever the censoring and failure distributions are conditionally independent given treatment arm. However, our tests remain asymptotically distribution-free -level tests in the presence of informative censoring provided either of our assumptions are true. In contrast, a weighted log-rank test will be an -level test in the presence of informative censoring only if (1) one of our two non-identifiable assumptions hold, and (2) the distribution of time to censoring is the same in the two treatment arms. We also study the estimation, in the presence of informative censoring, of the effect of treatment on the evolution over time of the mean of repeated measures outcome such as CD4 count.