Choice of Indicator Determines the Significance and Risk Obtained from the Statistical Association Betwen Fine Particulate Matter Mass and Cardiovascular Mortality
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Minor changes in the indicator used to measure fine PM, which cause only modest changes in Mass concentrations, can lead to dramatic changes in the statistical relationship of fine PM mass with cardiovascular mortality. An epidemiologic study in Phoenix (Mar et al., 2000), augmented to include PM1 (Kegler et al., 2000), provides a suitable data set to demonstrate these relationships. The t-statistic and the % increases in risk of cardiovascular death for an inter-quartile increase in PM concentrations will be compared for several fine PM indicators.