Table 1.

Conceptual and operational definitions of the structural features of the built environment

Structural measure	Conceptual definition	Operational definition
Reach	Street distance covered when walking a specific distance from a single location in all possible directions.57 Reach will be greater in areas with smaller compared to larger blocks.	A continuous measure, in miles, of the street distance covered when walking one mile from the residents’ block in all possible directions. Higher scores indicate greater reach.
Connectivity	The extent to which a street is connected within its local or immediate neighborhood (See58).	The mean number of streets connecting with each street in the area within a ½ mile radius from survey participant’s residential block. A continuous measure, with higher scores indicating greater connectivity
Integration	The extent to which a street segment or set of streets is more or less accessible from all other parts of the city (See58).	The mean value of the integration measure for all streets within a ½ mile radius from survey participant’s residential block. A continuous measure with higher scores indicating greater integration relative to other streets in the city.
Density	A continuous number representing the mean number of residential households/acre.	The mean number of households/acre for the ½ mile radius surrounding each survey participant’s residential block, based on data from the Census 2000 Summary File 1.
Land Use Mix	A measure of residential, commercial, industrial uses, with scores equal to one when land use is maximally mixed (e.g., similar proportions of multiple land uses) or heterogeneous and zero when land use is maximally homogeneous (e.g., all residential).16,25 Created using land use data by parcel for a neighborhood.	The average land use mix for the 1/2 mile radius surrounding each survey participant’s residential block, using parcel data provided by the Southeast Michigan Council of Governments (2000 and 2005). Neighborhoods in this study were primarily residential (with scores closer to zero). Higher scores reflect neighborhoods with more commercial or industrial land uses.