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 1

Descriptive statistics.

Variable type	Variable description	Variable symbols	No violations			Existence of violations
			(%)	MI (%)	FS (%)	(%)	MI (%)	FS (%)
Sex	Female	—	10.82	41.40	18.37	14.97	36.39	11.60
	Male		1.73	21.11	6.57	5.43	27.32	4.30
Age	<18	—	0.78	3.93	0.62	3.09	6.74	0.37
	18–32		1.99	6.18	1.47	4.21	8.04	0.75
	32–46		3.18	11.25	3.57	4.49	10.48	1.87
	46–60		4.79	21.79	8.31	5.89	19.27	6.27
	>60		1.81	19.35	10.97	2.71	19.18	6.64
Pavement condition	Pavement good	—	11.69	61.94	24.53	17.31	62.39	15.43
	Pavement damage		0.85	0.57	0.41	3.09	1.31	0.47
Road surface condition	dry	—	11.82	57.75	23.08	19.36	58.84	14.41
	damp		0.72	4.76	1.86	1.03	4.86	1.50
Lighting conditions	Day	—	7.87	42.74	16.51	14.87	44.90	10.48
	Dusk/dawn		1.11	3.67	2.10	0.75	2.71	1.03
	Street lights at night		2.25	10.17	3.73	3.37	10.57	2.90
	No street lamp at night		1.32	5.92	2.61	1.59	5.52	1.50
The road alignment	Straight	—	10.66	55.19	20.67	19.08	57.81	14.59
	Tortuous		1.89	7.32	4.27	1.31	5.89	1.31
Road type	General urban Road	—	5.41	23.00	6.24	10.38	29.75	5.61
	Class I-IV highway		3.67	23.26	12.06	5.89	21.23	7.20
	Substandard highway		3.47	16.25	6.65	4.12	12.72	3.09
Crash site	Motorway	—	8.10	43.91	18.03	11.23	38.63	12.35
	Nonmotorized lane		2.41	8.75	3.00	5.89	16.18	1.50
	Mixed lane		1.37	7.19	2.41	2.62	6.08	0.84
	Sidewalk		0.67	2.66	1.50	0.65	2.81	1.22
Pavement material	Asphalt	—	11.88	59.30	23.10	20.11	61.37	15.25
	Nonbituminous		0.67	3.21	1.84	0.28	2.34	0.65
Impact angle	Side impact	—	7.74	49.86	19.38	13.10	47.15	11.60
	Frontal collision		4.06	13.38	1.40	1.78	6.55	1.31
	Rear impact		0.96	5.43	2.48	0.94	5.43	0.94
	Other angles		3.18	3.16	1.68	4.58	4.58	2.06
Traffic control mode	Signal control	—	2.87	12.86	4.68	5.05	14.78	1.87
	Uncontrolled		3.54	23.75	11.88	5.14	23.57	37.51
	Marking control		6.13	25.90	9.16	10.20	25.35	4.58
Weekly parameters	Working days	—	9.34	45.30	17.00	14.59	47.24	11.60
	Rest day		3.21	17.21	7.94	5.80	16.46	4.30
Season	Spring	—	4.09	18.47	7.71	7.02	19.08	5.14
	Summer		2.85	15.19	4.86	6.64	19.08	3.18
	Autumn		3.29	17.59	7.30	3.74	15.25	5.33
	Winter		2.33	11.25	5.07	2.99	10.29	2.25
Weather	Sunny	—	11.38	20.57	22.17	19.08	55.75	13.66
	Severe weather		1.16	4.14	2.77	1.31	7.95	2.25
Visibility	>200 m	—	7.61	37.80	14.70	13.47	39.10	9.07
	<200 m		4.94	24.71	10.25	6.92	24.60	6.83
Terrain	Flat	—	10.04	52.99	19.97	18.33	56.22	13.10
	Nonflat		2.51	9.52	4.97	2.06	7.48	2.81

Note. “”is a reference variable.