Table 2

IRRs comparing injuries preintervention and postintervention, by injury type, for all roads and for 20 mph roads only

	Injury severity	IRR (95% CI)*	P value
All roads (20 and 30 mph roads)	Fatal	0.37 (0.14 to 0.98)	0.04
	Serious	1.02 (0.77 to 1.34)	0.86
	Slight	0.94 (0.84 to 1.06)	0.39
20 mph roads only	Fatal	0.65 (0.15 to 2.83)	0.57
	Serious	0.84 (0.60 to 1.17)	0.32
	Slight	0.91 (0.78 to 1.07)	0.26

*Controlling for calendar year (continuous variable) and areas (categorical variable).
IRR, incidence rate ratio.