Table 3

Average census block group-level descriptive statistics of reliability sample areas (mean, SD)
Study site Median household income ($) Median age (years) Percent of residents with college degree or higher (%) Percent residents non-Hispanic White (%) Net Residential Densitya Intersection Densityb Retail Floor Area Ratioc Mixed Used
San Diego County, CA 47,293 (14,715) 35.0 (6.8) 21.0 (16.1) 62.2 (24.1) 3.98 (3.35) 46.64 (20.59) 0.22 (0.15) 0.20 (0.16)
Seattle/King County, WA 52,267 (19,704) 36.1 (5.2) 38.3 (18.9) 70.6 (20.8) 8.56 (7.25) 61.12 (21.27) 0.27 (0.15) 0.31 (0.19)
Baltimore, MD-DC 49,874 (19,991) 38.0 (6.2) 34.7 (24.5) 62.6 (28.6) 9.66 (8.54) 49.34 (24.79) 0.33 (0.21) 0.33 (0.19)
Overall 49,590 (17,767) 36.0 (6.2) 30.0 (20.6) 65.2 (24.2) 6.80 (6.67) 52.29 (22.60) 0.26 (0.17) 0.27 (0.19)

a Residential units/acres of residential land.

b Number of intersections per square kilometer.

c Ratio of total building floor area to total parcel area.

d Entropy measure of building floor area for mixed use (uses include 5 categories: civic and educational, entertainment, commercial, multi- and single-family, office).

Millstein et al.

Millstein et al. BMC Public Health 2013 13:403   doi:10.1186/1471-2458-13-403

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