Table 2.

Estimation results for the proposed four model forms.

	Basic binary Logistic Model			RE Logistic Model			RP Logistic Model			Two-Level Logistic Model
Variables	Mean	SD	p-Value	Mean	SD	p-Value	Mean	SD	p-Value	Mean	SD	p-Value
Intercept	–4.41	2.99	0.139	–4.42	2.99	0.139	–4.01	4.37	0.359	–2.69	3.46	0.437
Environmental Factors
Speed limit	0.40 **	0.01	0.007	0.40 **	0.01	0.007	0.06 **	0.02	0.016	0.04 **	0.02	0.035
Number of lanes	−2.91 **	1.04	0.005	−2.91 **	1.04	0.005	−4.90 **	1.99	0.014	−4.29 **	1.29	0.008
Traffic volume	0.72 **	0.20	<0.001	0.72 **	0.20	<0.001	1.14 **	0.35	0.001	1.41 **	0.40	0.004
Rainy	3.24 **	1.13	0.004	3.24 **	1.13	0.004	4.22 **	1.35	0.002	2.84 **	1.26	0.024
Cloudy	2.74 **	1.11	0.014	2.74 **	1.11	0.014	2.96 **	1.27	0.020	2.42 **	1.20	0.044
Tunnel	1.97 **	0.66	0.003	1.97 **	0.66	0.003	2.25 **	0.94	0.016	2.47 **	0.63	<0.001
Bridge	2.62 **	1.10	0.017	2.62 **	1.10	0.017	3.72 **	1.58	0.018
Crash attributes
Truck involvement	0.67 *	0.38	0.075	0.67 *	0.38	0.075	0.83 *	0.48	0.085
Trailer truck involvement	1.99 **	0.73	0.006	1.99 **	0.73	0.006	3.06 **	1.14	0.007
Interactions
Single-vehicle primary crash × secondary CC	−0.11	0.34	0.748	−0.11	0.34	0.748	−0.61	0.50	0.222	0.09	0.55	0.875
Two-vehicle primary crash × secondary CC	−1.33 **	0.52	0.010	−1.33 **	0.52	0.010	−2.15 **	0.81	0.008	−1.80 **	0.87	0.012
Weekend × secondary CC	−1.01 **	0.43	0.017	−1.01 **	0.43	0.017	−1.45 **	0.64	0.023
Tunnel × secondary CC	1.31 *	0.71	0.064	1.31 *	0.71	0.064	2.48 *	1.15	0.031
Truck involvement × secondary CC										2.80 **	0.87	0.001
Random Effects (SD)
Cloudy							2.75 **	1.06	0.009
Double-vehicle primary crash × secondary CC										0.002	1.22	0.989
Truck involvement × secondary CC										4.24 × 10−5	0.89	0.999
${\sigma }_v$ (random intercept)				0.23	1.13	0.984				1.00 **	0.50	0.045
$\rho$				0.13	――	――

* means the estimated coefficient is significant at the 90% confidence level. ** means the estimated coefficient is significant at the 95% confidence level or above.