Abstract

Quantitative reanalyses of data from various laboratories have been done for more than 30 years. However, the development of more formal rules for combining the results of controlled trials, the adaptation of existing statistical techniques to this type of data, and the development of new methods to advance such secondary analyses have taken place only over the past decade. Although the process of combining and synthesizing the results from separate but similar experiments — called meta-analysis — is still controversial, it is steadily gaining ground. In the area of health effects of ozone on pulmonary function, the objective of meta-analyses has been to characterize the ozone dose-effect relationship from diverse studies. Attempts have also been made to test the validity of the previously advanced notion of “effective dose,” the product of ozone concentration, minute ventilation, and duration of exposure (Silverman et al. 1976). One study of pooled data found that a linear regression model expressed the best dose-effect association; the author also concluded that the “effective dose” concept is valid (Colucci 1983). However, a later study based on a larger data set reported a quadratic function as the best-fitting model and implicitly demonstrated that in its present mathematical form, “effective dose” might be invalid (Hazucha 1987). Subsequent studies appear to support the conclusions of the latter study.

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