TABLE 2—

Difference-in-Difference Analysis of Assault Mortality by Gender: Australia 1978–2015

Variable	RR (95% CI)
Women
Age group, y
15–29	1 (Ref)
30–44	1.03 (0.96, 1.11)
45–59	0.72 (0.66, 0.78)
≥ 60	0.48 (0.44, 0.53)
Method
Nonfirearm	1 (Ref)
Firearm	0.41 (0.31, 0.53)
Year	0.992 (0.984, 1.000)
Period
Before NFA	1 (Ref)
After NFA	1.37 (0.98, 1.92)
Firearm–year interaction
Nonfirearm	1 (Ref)
Firearm	0.978 (0.962, 0.995)
NFA–year interaction
Before NFA	1 (Ref)
After NFA	0.980 (0.967, 0.992)
NFA–method interaction
Before NFA–nonfirearm	1 (Ref)
Before NFA–firearm	1 (Ref)
After NFA–nonfirearm	1 (Ref)
After NFA–firearm	1.96 (0.76, 5.08)
NFA–method–year interaction (DiD term)
Before NFA–nonfirearm	1 (Ref)
Before NFA–firearm	1 (Ref)
After NFA–nonfirearm	1 (Ref)
After NFA–firearm	0.967 (0.936, 0.999)
Men
Age group, y
15–29	1 (Ref)
30–44	1.16 (1.10, 1.22)
45–59	0.84 (0.79, 0.90)
≥ 60	0.49 (0.46, 0.53)
Method
Nonfirearm	1 (Ref)
Firearm	0.45 (0.37, 0.55)
Year	1.003 (0.997, 1.009)
NFA period
Before NFA	1 (Ref)
After NFA	1.77 (1.39, 2.53)
Firearm–year interaction
Nonfirearm	1 (Ref)
Firearm	0.976 (0.964, 0.988)
NFA–year interaction
Before NFA	1 (Ref)
After NFA	0.971 (0.963, 0.980)
NFA–method interaction
Before NFA–nonfirearm	1 (Ref)
Before NFA–firearm	1 (Ref)
After NFA–nonfirearm	1 (Ref)
After NFA–firearm	1.01 (0.56, 1.82)
NFA–method–year interaction (DiD term)
Before NFA–nonfirearm	1 (Ref)
Before NFA–firearm	1 (Ref)
After NFA–nonfirearm	1 (Ref)
After NFA–firearm	0.997 (0.977, 1.018)

Note. CI = confidence interval; DiD = difference in difference; NFA = Australian National Firearms Agreement; RR = rate ratio.