Table 2.
Impact of ShotSpotter technology on firearm homicides, murder arrests, and weapons arrests among large metropolitan counties in the USA, 1999–2016
| Covariates | Firearm homicides | Murder arrests | Weapons arrest | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Incidencerate ratio (IRR) | 95% CI:lower | 95% CI:upper | IRR | 95% CI:lower | 95% CI:upper | IRR | 95% CI:lower | 95% CI:upper | |
| ShotSpotter | 1.035 | 0.84 | 1.27 | 0.993 | 0.73 | 1.36 | 0.929 | 0.75 | 1.15 |
| Firearm laws | |||||||||
| Right-to-carry | 1.214 | 1.05 | 1.41 | 0.489 | 0.27 | 0.88 | 0.750 | 0.52 | 1.08 |
| Permit-to-purchase | 0.843 | 0.72 | 0.99 | 0.507 | 0.23 | 1.14 | 0.872 | 0.54 | 1.40 |
| Violent misdemeanor prohibitions | 1.107 | 0.98 | 1.24 | 1.260 | 1.02 | 1.58 | 1.033 | 0.88 | 1.22 |
| Stand your ground | 1.060 | 0.95 | 1.19 | 0.885 | 0.64 | 1.22 | 0.995 | 0.87 | 1.14 |
Significance assessed at p < 0.05. Covariates with significant associations are italicized. Northeast used as reference in region. Each model contains year fixed effects and random intercept terms for firearm homicides at the county and state level. We employed robust estimators of variance, clustered at the county level