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Table 2 Incidence Rate Ratios of Mass Shootings in U.S. Counties, Multilevel Models

From: Income inequality and mass shootings in the United States

  MSA: Three or More Injuries MSA: Four or More Deaths Mother Jones: Four or More Deaths USA Today: Four or More Deaths
Adj. IRR (95% CI) Adj. IRR (95% CI) Adj. IRR (95% CI) Adj. IRR (95% CI)
Level 1 = County-Level
 Income inequality 1.56 (1.33, 1.83) 1.62 (1.34, 1.96) 1.46 (1.09, 1.97) 1.32 (1.04, 1.69)
 Poverty rate 1.28 (0.89, 1.83) 0.98 (0.61, 1.57) 0.81 (0.48, 1.38) 1.29 (0.66, 2.53)
 Unemployment rate 1.15 (0.88, 1.50) 1.09 (0.80, 1.48) 1.17 (0.80, 1.71) 0.95 (0.63, 1.42)
 Population density 0.13 (0.00, 1.87) 0.16 (0.29, 0.93) 0.14 (0.02, 0.92) 0.60 (0.00, 48.61)
 Young population 1.01 (0.77, 1.34) 0.97 (0.68, 1.37) 1.19 (0.86, 1.63) 1.07 (0.81, 1.40)
 Minority population 4.59 (0.70, 29.95) 16.31 (3.92, 67.87) 21.03 (4.84, 91.33) 3.08 (0.33, 28.09)
 HS graduation rate 0.66 (0.47, 0.92) 0.65 (0.42, 1.01) 0.66 (0.40, 1.08) 0.65 (0.39, 1.07)
 2010–2015 2.98 (1.97, 4.51) 1.78 (1.07, 2.99) 1.51 (0.77, 2.96) 1.35 (0.75, 2.43)
Level 2 = State-Level
 Right to carry laws 0.63 (0.19, 2.06) 6e−30 (6e− 125, 5e+ 65) 0.18 (0.00, 34.43) 0.08 (0.00, 24.13)
 Assault rifle ban 0.88 (0.25, 3.09) 1.33 (0.45, 3.89) 1.37 (0.41, 4.49) 1.72 (0.60, 4.94)
 Wald Chi-Square 127.77 61.65 40.98 16.01
 County-Decades (N) 6273 6273 6273 6273
  1. Adj. IRR adjusted incidence rate ratio, CI confidence interval. All variables are logged and z-score standardized. Robust standard errors clustered by county reported