Research
Assessing community variation and randomness in public health indicators
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* Corresponding author: Stephan Arndt stephan-arndt@uiowa.edu
1 Department of Psychiatry, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242 USA
2 Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, Iowa 52242, USA
3 Iowa Consortium for Substance Abuse Research and Evaluation, 100 Oakdale Campus M308 OH, University of Iowa, Iowa City, Iowa 52245-5000, USA
4 Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, Iowa 52242, USA
5 Iowa Department of Public Health, Des Moines, Iowa, USA
6 Department of Occupational & Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa 52242, USA
Population Health Metrics 2011, 9:3 doi:10.1186/1478-7954-9-3
Published: 2 February 2011Abstract
Background
Evidence-based health indicators are vital to needs-based programming and epidemiological planning. Agencies frequently make programming funds available to local jurisdictions based on need. The use of objective indicators to determine need is attractive but assumes that selection of communities with the highest indicators reflects something other than random variability from sampling error.
Methods
The authors compare the statistical performance of two heterogeneity measures applied to community differences that provide tests for randomness and measures of the percentage of true community variation, as well as estimates of the true variation. One measure comes from the meta-analysis literature and the other from the simple Pearson chi-square statistic. Simulations of populations and an example using real data are provided.
Results
The measure based on the simple chi-square statistic seems superior, offering better protection against Type I errors and providing more accurate estimates of the true community variance.
Conclusions
The heterogeneity measure based on Pearson's χ2 should be used to assess indices. Methods for improving poor indices are discussed.