Constructing built environment indices using alternative standardizations and spatial scales
Methods: In 2008 and 2011, the Children’s Environmental Health Initiative conducted parcel-level assessments of 57 BE variables in Durham, NC (parcel N=30,293). Based on a priori defined variable groupings, we constructed 7 mutually exclusive BE domains (crime, tenancy, nuisances, housing damage, property disorder, vacancy, and security). Domain-based indices were developed by standardizing component variables according to count per parcel, count per parcel area, and proportion of census block area with a given variable. A raw count was used for comparison. Component variables were aggregated to the census block and primary and secondary adjacency levels. Preservation of rank was calculated (Spearman’s rho) within each index (across standardizations) and among indices (within standardization). To assess validity by standardization, we examined correlations among indices and census variables.
Results: Security was impacted by standardization (0.68<rho<0.91) while ranking of other indices was preserved. The relationship between tenancy and security was less preserved across standardizations (-0.16<rho<0.58) than the relationships among other indices. For each BE index, the correlation with census variables depended on standardization (0.27<rho<0.71). Indices constructed at varying spatial scales that smooth over administrative boundaries resulted in less variability within index.
Conclusion: Standardization choice substantively altered ranking within selected indices, relationships among indices, and relationships among indices and census variables. This has implications for measuring aspects of BE, both singly and jointly, particularly when linking BE indices to health outcomes. Associations with health outcomes should be evaluated in terms of alternative standardizations and spatial scales.
Learning Areas:Public health or related research
Explain the importance of considering alternative standardizations when constructing indices. Identify ways to determine if an index is valid and reliable.
Keyword(s): Built Environment, Methodology
Qualified on the content I am responsible for because: Julie Strominger serves as a statistician at the Childrenâs Environmental Health Initiative. Her scientific interests include index construction and implications of indices when tying to health outcomes.
Any relevant financial relationships? No
I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.