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Figure 1 | Environmental Health

Figure 1

From: Power estimation using simulations for air pollution time-series studies

Figure 1

Power estimates from simulations varying time-series length and daily outcome counts (Scenario Set 1). Power estimates are for PM2.5 in relation to CVD (a), dysrhythmia (b), and cardiac arrest (c). Simulated daily outcome counts were generated for each scenario with average daily counts corresponding to average counts in one year of observed data; with the specified temporal associations with air pollutants; and with associations with variables relating to time and meteorology that reflected the associations in the one year of observed data. For each scenario, the mean daily counts were scaled appropriately, time series of the specified length were created, and 2000 simulated data sets were generated based on a Poisson distribution. Power was calculated as the percentage of the 2000 simulated data sets for each scenario that showed a statistically significant association between the pollutant and the simulated daily outcome counts, using a significance level of 0.05.

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