TABLE 2—

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

Variable	IRR (95% CI)	P	Interpretation
Gun ownership	1.009 (1.004, 1.014)	.001	For each 1 percentage point increase in proportion of household gun ownership, firearm homicide rate increased by 0.9%
Percentage Black	1.052 (1.037, 1.068)	.001	For each 1 percentage point increase in proportion of Black population, firearm homicide rate increased by 5.2%
Gini coefficient	1.046 (1.003, 1.092)	.037	For each 0.01 increase in Gini coefficient, firearm homicide rate increased by 4.6%
Violent crime rate	1.048 (1.010, 1.087)	.013	For each increase of 1/1000 in violent crime rate, firearm homicide rate increased by 4.8%
Nonviolent crime rate	1.008 (1.003, 1.013)	.002	For each increase of 1/1000 in nonviolent crime rate, firearm homicide rate increased by 0.8%
Incarceration rate	0.995 (0.991, 0.999)	.027	For each increase of 1/10 000 in incarceration rate, firearm homicide rate decreased by 0.5%

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.