TABLE 3—

Results of Final Model for Significant Predictors of Age-Adjusted Firearm Homicide Rate, Using Standardized Predictor Variables: United States, 1981–2010

Variable	IRR (95% CI)	P	Interpretation
Gun ownership	1.129 (1.061, 1.201)	.001	For each 1-SD increase in proportion of household gun ownership, firearm homicide rate increased by 12.9%
Percentage Black	1.828 (1.536, 2.176)	.001	For each 1-SD increase in proportion of black population, firearm homicide rate increased by 82.8%
Gini coefficient	1.129 (1.007, 1.266)	.037	For each 1-SD increase in Gini coefficient, firearm homicide rate increased by 12.9%
Violent crime rate	1.154 (1.031, 1.291)	.013	For each 1-SD increase in violent crime rate, firearm homicide rate increased by 15.4%
Nonviolent crime rate	1.100 (1.036, 1.168)	.002	For each 1-SD increase in nonviolent crime rate, firearm homicide rate increased by 10.0%
Incarceration rate	0.928 (0.868, 0.992)	.027	For each 1-SD increase in incarceration rate, firearm homicide rate decreased by 7.8%.

Note. CI = confidence interval; IRR = incidence rate ratio. Final model incorporated only variables whose parameter estimates were significant at the P < .05 level. Model included fixed effects for year and adjustment for clustering within states.