Analysis of Factors Affecting the Severity of Injuries in Electric Two-Wheeled Vehicle Crashes with or without Violation: A Random Parametric Logit Model considering Heterogeneity of Means and Variances

Table 5

Estimating the severity of injuries in electric two wheeled vehicle accidents using a random parameter logit model considering the heterogeneity of mean and variance.

Variable	No violation				Existence of violation
	MI		SF		MI		SF
	Mean	S.D	Mean	S.D	Mean	S.D	Mean	S.D
Rider factor
Male	—	—	—	—	−1.188	0.240	−0.958	0.873
18–32	−0.236	0.154	—	—	—	—	—	—
46–60	—	—	—	—	—	—	0.796	0.655
>60	0.151	0.178	0.347	0.212	0.786	0.975	2.017	1.316
Road factor
Pavement damage	−2.241	0.231	—	—	—	—	0.148	0.247
Dusk/dawn	—	—	—	—	−0.493	0.347	—	—
Street lights at night	−1.145	0.175	—	—	0.258	0.455	—	—
No street lamp at night	0.767	0.159	0.838	0.233	0.426	0.725	—	—
Nonmotorized lane	—	—	—	—	−0.288	0.105	−0.554	0.143
Mixed lane	1.323	0.135	1.171	0.197	0.723	0.535	0.571	0.397
Sidewalk	—	—	−0.552	0.155	—	—	—	—
Collision factor
Other angles	—	—	−1.156	0.237	−1.668	0.537	−1.325	0.736
Environmental factor
Uncontrolled	−0.236	0.135	−0.456	0.142	0.320	0.294	—	—
Marking control	—	—	—	—	0.532	0.322	—	—
Autumn	0.367	0.155	—	—	—	—	—	—
Severe weather	1.149	0.211	—	—	0.804	1.103	—	—
<200 m	—	—	0.485	0.181	—	—	0.249	0.645
Random parameter
Severe weather	0.804	0.212	—	—	1.149	1.853	—	—
<200 m	—	—	0.260	0.738	—	—	0.486	1.163
Heterogeneity in the means of random parameters
Severe weather: No street lamp at nigh	—	—	—	—	0.301	0.217	—	—
Severe weather: >60	0.433	0.212	—	—	—	—	—	—
Severe weather: Uncontrolled	—	—	—	—	−0.532	1.123	—	—
<200 m: Mixed lane	—	—	−0.322	0.671	—	—	0.525	0.278
Heterogeneity in the variances of random parameters
Severe weather: >60	1.588	0.205	—	—	—	—	—	—
Severe weather: No street lamp at nigh	—	—	—	—	1.237	0.512	—	—
<200 m: Mixed lane	—	—	—	—	—	—	1.307	1.062