Linkage bias in estimating the association between childhood exposures and propensity to become a mother: an example of simple sensitivity analyses

Summary.  Record linkage is a powerful tool to obtain individual follow-up information that is held in routinely collected databases. However, this method is potentially limited not only by the quality of the original data but also by the temporal and geographic coverage of the routine data. Migration in particular is a factor that might introduce systematic bias even in analyses of data covering relatively large geographical areas. We describe a linkage application where emigration bias might be an issue and use the sensitivity analysis approach that has been described by Molenberghs and co-workers and Kenward and co-workers to assess the extent of this bias.     

A reducible four-parameter system of model life tables

Abstract In this paper a four-parameter extension of Brass's relational system of model life tables is suggested that (1) matches a wide range of empirical age patterns of mortality, (2) is easy to apply, especially to partial life tables, and (3) contains demographically meaningful parameters. A test of the model on a set of 62 empirical life tables indicates that four parameters are necessary and sufficient for fitting a wide range of mortality patterns. A further test on an historical series of Swedish life tables reveals a consistent pattern of mortality change. Examination of the parameters for a set of geographicallyrelated life tables suggests a way to define families of life tables. Identification of such temporal and spatial relationships allows the model to be reduced to a form with twoor three-parameters for application to incomplete or inaccurate data.     

Investment-Promoting Policies in the Presence of International Interactions

Investment-promoting policies in a small open economy are analyzed by means of a dynamic applied general equilibrium model with overlapping generations. Simulations of a decrease of the corporate income tax rate and an increase of the investment tax credit rate are discussed and compared. This paper examines in particular the extent to which international trade and capital flows interfere in both tax policies. The modeling of overlapping generations allows moreover to identify the winners and losers of these reforms. It is shown that the subsidy policy is preferred to the profit tax policy when a small open economy seeks to stimulate capital formation.     

Replacement Migration: Is it a Solution to Declining and Aging Populations?

Population and Environment - This report looks at the recent publication prepared by the UN Population Division which examines the demographic situation in most advanced nations, but especially in...     

Communicating Under Section 112(r) of the Clean Air Act Amendments

Regulations under Section 112(r) of the 1990 Clean Air Act Amendments require fixed facilities having threshold quantities of materials on the U.S. Environmental Protection Agency's list of regulated substances to disclose to the general public the expected offsite consequences of worst-case accidental chemical releases. This paper describes the communication practices of small firms in Delaware and New Jersey and the practical problems these facilities might encounter complying with the proposed rule. The paper reports an interesting difference between the apprehension voiced by small firms required to report worst-case release information and the public's apparent lack of interest in such information. Unlike the difficulty expected by small firms in calculating and communicating worst-case chemical release information, this paper includes some observations on the ability of large chemical firms to comply with the proposed requirements.     

Identifying Dangerous Trucking Firms

The paper develops a statistical procedure for predicting the safety performance of motor carriers based on characteristics of firms and results of two government safety enforcement programs. One program is an audit of management safety practices, and the other is a program to inspect drivers and vehicles at the roadside for compliance with safety regulations. The technique can be used to provide safety regulators with an empirical approach to identify the most dangerous firms and provide a priority list of firms against which educational and enforcement actions should be initiated. The government needs to use such an approach rather than directly observing accident rates because the most dangerous firms are generally small and, despite relatively high accident rates, accidents remain rare events. The technique uses negative-binomial regression procedures on a dataset of 20,000 firms. The definition of poor performance in roadside inspection is based on both the rate of inspections per fleet mile and the average number of violations found during an inspection. This choice was made because selection for inspection has both a random and nonrandom component. The results of the study suggest that both of the government's safety programs help identify the most dangerous firms. The 2.5% of firms that do poorly in both programs have an average accident rate twice that of the mean for all other firms.     

A review of research on techniques for lifting low-lying objects: 2. Evidence for a correct technique

Teaching 'correct' lifting technique is common, with squat lifting generally recommended. However the available evidence is less clear about which technique should be favoured. The purpose of this paper was to present an accessible synthesis of the evidence to assist professionals in their decision about whether to teach a specific technique for lifting objects lying on or near the ground. Squat, stoop and semi-squat techniques are described and the psychophysical, physiological, biomechanical, psychological, performance and clinical evidence for each technique summarised. Evidence for other lifting guidelines is also presented. It is concluded that no one technique has clear evidence and that a work design approach should be the prime focus of intervention. Recommendations for correct lifting technique guidelines are given for where technique training must be provided.     

Paternalism and the young

A critical analysis is made of the concept of paternalism, and the manner in which protective measures on behalf of children often result in a denial of rights to the young. The article challenges the assumption that parents invariably know the needs of their own children, and accordingly act on their behalf. Similar reservations are made as to the capacity of official caretakers acting as agents of the state, to replace parents who are at fault. Conversely, it is suggested that children often have greater capabilities to function independently than is generally acknowledged. However, attention is also drawn to the defects in the arguments of some child-rights advocates. In sum, the article argues for the need to seek out legitimate paternalistic practices where genuinely needed, where sufficient consideration has been given to the capacities of the young for an independent life, and where sufficient sensitivity has been shown to their aspirations.     

Foreign-born professionals in the United States

This paper is an abridged version of a longer study by the same name published by the Center for Immigration Studies, 1815 H Street, NW, Washington, DC 20006.