1 11/11/99Measurement error in time-series studies Misclassification of exposure is a well-recognized, inherent limitation of epidemiologic studies of disease and the environment. For many agents of interest, exposures take place over time and in multiple locations; accurately estimating the relevant exposures for an individual participant in epidemiologic studies is often daunting, particularly within the limits set by feasibility, participant burden, and cost. Researchers have taken steps to deal with the consequences of measurement error by limiting the degree of error through a study’s design, estimating the degree of error using a nested validation study, and by adjusting for measurement error in statistical analyses. In this paper, we address measurement error in observational studies of air pollution and health. Because measurement error may have substantial implications for interpreting epidemiologic studies on air pollution, particularly the time series analyses, this paper sets out a systematic conceptual formulation of the problem of measurement

participants at the June preconference and December conference for their helpful suggestions and

The trend toward earlier and earlier retirement was one of the most important labor market developments of the twentieth century. It was evident in all the major industrialized countries. In the United States, however, the trend toward earlier retirement came to at least a temporary halt in the mid-1980s. Male participation rates at older ages have stabilized or even increased slightly. Older women’s participation rates are clearly rising. This paper examines the environmental and policy changes contributing to the long-term decline in the U.S. retirement age as well as developments that contributed to the recent reversal. The dominant source of earlier retirement was the long-term increase in Americans ’ wealth, which permitted workers to enjoy rising living standards even as they spent a growing percentage of their lives outside the paid work force. The expansion of Social Security pensions and of employer-sponsored pension plans and the introduction of mandatory retirement rules also encouraged earlier retirement over much of the last century. Many public policies and private institutions that encouraged early retirement have been modified in recent years. Mandatory retirement has been outlawed in most jobs. Social Security is no longer

Visualization schemas and a web-based

Abstract: This paper introduces a new version of Ergonomic Criteria for HVEIs which have been tested for validity. An assignment experiment (Ergonomic Criteria X Usability Problems) has been conducted to ensure the appropriate understanding of the different criteria. The results of this study identify the criteria that are well understood and the ones that need further improvement.

The author(s) shown below used Federal funds provided by the U.S. Department of Justice and prepared the following final report:

this paper we describe a model representation and algorithm for deriving structured quality indicators and auditing protocols from formalized specifications of guidelines used in decision support systems. We apply the model and algorithm to the assessment of physician concordance with a guideline knowledge model for hypertension used in a decision-support system. The properties of our solution include the ability to derive automatically (1) context-specific and (2) case-mix-adjusted quality indicators that (3) can model global or local levels of detail about the guideline (4) parameterized by defining the reliability of each indicator or element of the guideline

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Research article Mariner mutagenesis of Brucella melitensis reveals genes with previously uncharacterized roles in virulence and survival

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