Table 4.

Dispatch decision tree by depth, model, misclassification costs and Over/under triage rates*

Depth	Model	Misclassification costs	Over triage (%)	Under triage (%)
1	A	1:1	85.2%	0.0%
3	B	1:1	36.0%	14.1%
3	B	1:2	52.4%	13.0%
3	B	1:3 to 1:4	66.0%	10.6%
3	B	1:5	71.9%	9.4%
3	B	1:6	73.8%	8.9%
3	B	1:7	75.6%	8.5%
3	B	1:8	76.9%	8.2%
3	B	1:9 to 1:12	82.3%	6.8%
3	B	1:13 to 1:18	84.7%	4.8%
3	B	1:19	85.2%	0.0%
3	C	1:1	40.5%	14.0%
3	C	1:2	53.5%	13.0%
3	C	1:3	64.9%	11.3%
3	C	1:4	66.3%	11.0%
3	C	1:5 TO 1:8	72.7%	10.1%
3	C	1:9	85.2%	0.0%
Unlimited (7)	D	1:1	35.4%	13.8%
Unlimited (7)	D	1:2	51.6%	12.7%
Unlimited (7)	D	1:3	61.7%	11.4%
Unlimited (7)	D	1:4	67.7%	9.9%
Unlimited (7)	D	1:5	70.7%	9.3%
Unlimited (7)	D	1:6	72.0%	9.0%
Unlimited (7)	D	1:7	76.2%	8.0%
Unlimited (7)	D	1:8	78.0%	7.4%
Unlimited (7)	D	1:9	78.6%	7.2%
Unlimited (7)	D	1:10 to 1:12	80.0%	6.7%
Unlimited (7)	D	1:13	82.6%	6.1%
Unlimited (7)	D	1:21	84.8%	2.7%
Unlimited (7)	D	1:22	85.2%	0.0%
Unlimited (7)	E	1:1	42.1%	13.6%
Unlimited (7)	E	1:2	52.5%	12.5%
Unlimited (7)	E	1:3	56.7%	12.1%
Unlimited (7)	E	1:4	69.8%	9.9%
Unlimited (7)	E	1:5 to 1:6	70.5%	9.7%
Unlimited (7)	E	1:7 to 1:8	73.5%	9.4%
Unlimited (7)	E	1:9	83.4%	7.8%
Unlimited (7)	E	1:10 to 1:11	83.5%	7.7%
Unlimited (7)	E	1:12	85.2%	0.0%

^*Model A variables were: MPDS dispatch codes

Model B variables were: MPDS dispatch codes, anyone trapped, vulnerable road user, airbag deployed, atmosphere, road surface

Model C variables were anyone trapped, vulnerable road user, anyone not ambulant, atmosphere, accident type

Model D variables were: MPDS dispatch codes, anyone trapped, vulnerable road user, anyone aged ≥ 75 years, day of the week, single v. multi-vehicle, airbag deployed, atmosphere, road surface, lighting, accident type

Model E variables were: MPDS dispatch codes, anyone trapped, vulnerable road user, anyone aged ≥ 75 years, day of the week, single v. multi-vehicle, airbag deployed, atmosphere, road surface, lighting, accident type