Keith Vodden Dr. Douglas Smith - Transports Canada

Appendix A—Detail on Calculations of the Ontario Model
Step 2
Allocate additional fatalities based on proportion of major injuries
Collision Severity
Fatal
Injury
ORSAR data
Additional
Fatalilties 50 Fatalilties 10
Major injuries 10 90
Fatalilties 50 + 1 9
Major injuries 10 - 1 90 - 9
Fatalilties 51 9
Major injuries 9 81
In the model for 2004, 7% of major injuries occur in fatal and 93% in injury
collisions. As a result, 7% (1) and 93% (13) of the misclassified major injuries are
assigned to fatal and injury collision categories respectively. Other years would use
different proportions based on the ORSAR data for that year.
The additional injuries (over ORSAR estimates) identified through the
MOH&LTC data and the Chipman re-analysis are allocated among collisions severity
categories based on the proportion (adjusted to allocate vehicles with unknown damage)
of demolished vehicles. This is illustrated in the hypothetical example below where 10%,
50% and 40% of the additional injuries are allocated to fatal, injury and PDO collisions to
reflect the proportion of demolished vehicles in these collision severity groups. We
believe injuries are highly correlated to vehicle damage and have therefore chosen this
allocation mechanism for additional injuries.
TNS Canadian Facts, Social and Policy Research 121