You are here:
Development of Water Quality Index for the United States: A Sensitivity Analysis
Citation:
JAGAI, J. S., K. Rapazzo, AND D. T. LOBDELL. Development of Water Quality Index for the United States: A Sensitivity Analysis. Presented at International Society for Environmental Epidemiology (ISEE) Annual Meeting, Columbia, SC, August 26 - 30, 2012.
Impact/Purpose:
Objectives: Develop a water quality index for all United States counties and assess index robustness to variable choices made during construction
Description:
Background: Water quality is quantified using several measures, available from various data sources, which can be combined to create a single index of overall water quality. It is necessary to identify appropriate variables to include in an index which could be used for health research. Objectives: Develop a water quality index for all United States counties and assess index robustness to variable choices made during construction. Methods: Data representing water quality were identified. For all counties (n=3141), variables were constructed and principal components analysis (PCA) used to assemble the index. Similar variables were derived from multiple data sources; index robustness was assessed by substituting roughly equivalent variables (ex: a measure for arsenic in water versus a measure for the numbers of arsenic regulation violations in public water). The primary index was developed using variables with optimal spatial and temporal coverage. Alternative indices were constructed either by exchanging a single variable or by exchanging all nine variables with available alternates (full alternate index). Concordance correlation coefficients (ccc) were used to assess similarity to primary index. Results: Sensitivity analysis demonstrated strong correlations when comparing alternates to the primary index. The lowest correlation was seen for the full alternate, compared to the primary, index (ccc: 0.99912 (95% CI: 0.99905, 0.99916)). Conclusions: Data representing environmental water quality was successfully combined into one index representing overall county level water quality. Sensitivity analysis demonstrated differing sources of variables did not alter county rankings indicating index robustness to measure choice. This abstract does not reflect EPA policy. Word count: 250 of 250