Table 2.
Relative risks associated with block group and city characteristics, among total injury crashes and crash types
| Crash rates relative to block-group population |
HBD crash rates relative to non-HBD crashes |
SVN crash rates relative to non-SVN crashes |
||||
|---|---|---|---|---|---|---|
| Variable Description | Median | (95% C.I.) | Median | (95% C.I.) | Median | (95% C.I.) |
| Alcohol outlet density (10s / sq. mile) | ||||||
| In local block group | 1.0273* | (1.0199, 1.0348) | 0.9929* | (0.9866, 0.9993) | 0.9627* | (0.9507, 0.9748) |
| Mean of adjacent block groups | 1.0836* | (1.0599, 1.1062) | 0.9787* | (0.9621, 0.9956) | 0.9093* | (0.8830, 0.9363) |
| City-level average | 1.2267* | (1.147, 1.3153) | 1.0097 | (0.9110, 1.1196) | 0.8955 | (0.7975, 1.0062) |
| Proportion of outlets bars/pubs | ||||||
| In local block group | 1.0064 | (0.9423, 1.0759) | 1.0907 | (0.9758, 1.2183) | 0.9946 | (0.8355, 1.1795) |
| Mean of adjacent block groups | 1.0175 | (0.8731, 1.1856) | 1.2346 | (0.9878, 1.5419) | 1.1444 | (0.8244, 1.5937) |
| City-level average | 2.2569* | (1.1872, 4.1247) | 3.3733 | (0.7363, 15.6442) | 10.3222* | (1.7038, 81.215) |
| Proportion of outlets restaurants | ||||||
| In local block group | 1.0290 | (0.9921, 1.0670) | 0.9408 | (0.8833, 1.0004) | 0.9593 | (0.8715, 1.0566) |
| Mean of adjacent block groups | 1.0814 | (0.9885, 1.1778) | 0.8135* | (0.7242, 0.9169) | 0.8898 | (0.7523, 1.0600) |
| City-level average | 0.9662 | (0.7176, 1.2710) | 0.8400 | (0.4196, 1.5270) | 0.8314 | (0.4216, 1.8908) |
| Population density (1000s / sq. mile) | 0.9155* | (0.9099, 0.9211) | 1.0015 | (0.9974, 1.0056) | 0.9797* | (0.9724, 0.9872) |
| Adjacent population (1000s) | 1.0084* | (1.0039, 1.0123) | 1.0045* | (1.0014, 1.0076) | 1.0031 | (0.9981, 1.0081) |
| City population (1000s) | 1.0003 | (1.0000, 1.0007) | 0.9998 | (0.9991, 1.0004) | 1.0000 | (0.9993, 1.0006) |
| Real income ($10,000) | 0.9494* | (0.9279, 0.9680) | 1.0029 | (0.9881, 1.0176) | 1.0193 | (0.9961, 1.0432) |
| Adjacent real income ($10,000) | 0.9588* | (0.9357, 0.9863) | 0.9910 | (0.9709, 1.0125) | 1.0607* | (1.0286, 1.0966) |
| Average household size | 0.8045* | (0.7676, 0.8456) | 1.1124* | (1.0622, 1.1657) | 1.1073* | (1.0265, 1.1900) |
| % Poverty | 1.0074* | (1.0034, 1.0111) | 0.9999 | (0.9975, 1.0022) | 1.0017 | (0.9979, 1.0055) |
| % Unemployment | 0.9951* | (0.9934, 0.9967) | 1.0019 | (0.9996, 1.0041) | 1.0019 | (0.9983, 1.0053) |
| Proportion age 20–24 | 0.9105 | (0.6021, 1.3485) | 0.6717 | (0.2714, 1.6599) | 2.1529 | (0.6618, 7.2812) |
| Proportion age 20–24 in Adjacent BG | 4.0755* | (2.0036, 8.1149) | 1.2991 | (0.3471, 4.8115) | 0.3835 | (0.0545, 2.5284) |
| Proportion age 25–44 | 0.5779* | (0.4174, 0.7652) | 0.9290 | (0.4878, 1.7034) | 1.7565 | (0.7803, 3.6455) |
| Proportion age 45–64 | 0.6598 | (0.4218, 1.0058) | 1.3409 | (0.6475, 2.6698) | 4.591* | (1.9753, 10.8623) |
| Proportion age 65+ | 0.3754* | (0.2516, 0.5614) | 0.9054 | (0.5518, 1.4342) | 0.7879 | (0.4083, 1.4989) |
| Proportion white | 0.7996 | (0.5739, 1.0906) | 1.4659* | (1.1166, 1.9621) | 1.6271* | (1.0859, 2.3533) |
| Proportion white in Adjacent BG | 0.4249* | (0.3187, 0.6162) | 1.2758 | (0.9109, 1.8070) | 1.0851 | (0.7311, 1.6659) |
| Proportion Black | 0.2973* | (0.1691, 0.4866) | 0.9826 | (0.6571, 1.4508) | 1.2315 | (0.6943, 2.1978) |
| Proportion Hispanic | 2.0285* | (1.6333, 2.5356) | 0.8719 | (0.7106, 1.0756) | 0.8118 | (0.5958, 1.1087) |
| Proportion male | 0.6645 | (0.4111, 1.1668) | 1.9314* | (1.1264, 3.3824) | 1.9477 | (0.9003, 4.5481) |
| Presence of any class 1–2 highway | 2.2733* | (2.1090, 2.4899) | 0.9686 | (0.9295, 1.0099) | 1.2127* | (1.1349, 1.2958) |
| Intercept | 5.9085* | (4.128, 9.1185) | 0.3162* | (0.1733, 0.6827) | 0.1170* | (0.0442, 0.2583) |
| Time trend (1–8) | 0.9543* | (0.9497, 0.9593) | 1.0336* | (1.0253, 1.0419) | 1.0547* | (1.0424, 1.0667) |
| SD (city-level random effect) | 0.0230 | (0.0230, 0.3004) | 0.2278 | (0.2004, 0.2621) | 0.2136 | (0.1743, 0.2563) |
| SD (CAR spatial random effect) | 0.5749 | (0.5749, 0.7037) | 0.3350 | (0.3016, 0.3681) | 0.3381 | (0.2718, 0.3984) |
| SD (non-spatial random effect) | 0.9481 | (0.9481, 1.0137) | 0.1740 | (0.1045, 0.2209) | 0.5196 | (0.4755, 0.5623) |
| Spatial proportion block grp. variance | 0.2478 | (0.2478, 0.3496) | 0.7876 | (0.6588, 0.9241) | 0.2975 | (0.1957, 0.4033) |
| Proportion variance due to city effects | 0.0004 | (0.0004, 0.0618) | 0.2672 | (0.2172, 0.3285) | 0.1060 | (0.0726, 0.1471) |
| CAR spatial autocorrelation (Moran’s I) | 0.6557 | (p < 0.00001) | 0.6730 | (p < 0.00001) | 0.6890 | (p < 0.00001) |
Notes: Posterior results are from Bayesian space-time Poisson analyses of 3870 Census block groups within 50 mid-sized California cities over the years 2001–2008 (total n = 30,960). Each Poisson model included an exposure variable with coefficient restricted to one, calculated on the assumption that outcome counts study-wide are distributed in exact proportion to population (total crash model) or to non-alcohol crashes (HBD and SVN crash models). Raw Poisson coefficients and credible intervals have been exponentiated and are thus interpretable as relative rates.