Table 1 Description of decision tree variables
Variable name | Variable type | Brief description |
|---|---|---|
Accident type | Dichotomous | Intersection/Midblock |
Airbag deployed | Dichotomous | Any airbag deployed/No deployed |
Anyone ejected | Dichotomous | Anyone ejected (incl. partial)/Everyone not ejected |
Anyone not ambulant | Dichotomous | Anyone not ambulant/Everyone ambulant (able to walk) |
Anyone trapped | Dichotomous | Anyone trapped in a vehicle/Everyone not trapped |
Atmosphere | Nominal | Smoke, Clear, Overcast, Raining, Fog |
Child | Dichotomous | Anyone aged ≤ 12 years/Everyone aged ≥ 13 years |
Day of the week | Nominal | Day of the week Sunday = 1 etc |
Lighting | Nominal | Daylight/Dawn or dusk/Dark with lights on/off/not provided |
MPDS dispatch code | Nominal | Medical Priority Dispatch System dispatch codes for Protocol 29 |
Older | Dichotomous | Anyone aged ≥ 75 years/Everyone aged ≤ 74 years |
Raining | Dichotomous | Raining/Clear |
Road alignment | Dichotomous | Curved/Straight |
Road grade | Nominal | Level/Crest of hill/Slope |
Road surface | Dichotomous | Sealed/Unsealed |
Rollover | Dichotomous | Any vehicle rolled over/No vehicle rolled over |
Single v. Multi-vehicle | Dichotomous | Single vehicle/2 or more vehicles |
Speed limit | Ordinal | Posted speed limit (km/h) |
Time of day | Continuous | hh:mm |
Traffic control | Nominal | Traffic lights/Stop sign/ Give way sign/Zebra crossing/ Railway crossing/ School crossing/No signal or control |
Type of intersection | Nominal | 4-way/3-way (T-junction)/Roundabout/Bridge/Rail Crossing/Driveway |
Vulnerable road user | Dichotomous | Involved vulnerable road user (cyclist, motorcyclist or pedestrian)/No vulnerable road user involved |