Table 2: Relative importance of variables.

VIM for freeways	VIM for two-lane two-way roads	independent variable
0.2137	0.8214	Seat belt
0.3773	0.1484	Cause of crash
0.2858	0.0088	Collision type
0.0197	0.0029	Vehicle type
0.0115	0.0023	Weather conditions
0.0115	0.0023	Age
0.0115	0.0023	Shoulder type
0.0115	0.0023	Shoulder width
0.0115	0.0023	Road surface condition
0.0115	0.0023	Lighting condition
0.0115	0.0023	Location type
0.0115	0.0023	Occurrence
0.0115	0.0001	Gender
1.0000	1.0000	Sum