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Fig. 5 | Environmental Health

Fig. 5

From: Exploring associations between multipollutant day types and asthma morbidity: epidemiologic applications of self-organizing map ambient air quality classifications

Fig. 5

Results from sensitivity analysis of number of categories. Panel a presents a Principal Component Analysis biplot of the multipollutant data in our study. Vectors depict the primary modes of variation in the data (i.e., loading weights) and circles reflect estimated Rate Ratios (RR) using Poisson regression for SOM generated multipollutant profiles from a range of classifications (categories n = 2:20) found to be significantly associated with our outcome (p < 0.05). Panel b presents the distribution of rate ratio estimates for each SOM classification. Categories found significant (p < 0.05) are colored black, and to indicate estimate stability, size of the symbol is inversely proportional to the estimated standard error (SE). Dashed lines reflect quartiles for the distribution of RRs across all classifications

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