A Crash Severity Prediction Method Based on Improved Neural Network and Factor Analysis

Table 5

Summary of FII expectation (K = 100) and relative percentage for two different methods.

Variables	Category	NN with PSO ()		NN with PSO ()
		FII	Relative percentage (%)	FII	Relative percentage (%)
Acctype	Nonroad	0.108	77.3	0.080	63.4
Month	Nonroad	0.088	63.1	0.102	81.0
Weekday	Nonroad	0.061	43.7	0.054	43.5
loc_type	Nonroad	0.080	57.1	0.076	60.1
rd_char1	Road	0.078	55.6	0.063	50.2
Rdsurf	Road	0.052	37.4	0.456	36.2
Light	Nonroad	0.069	49.1	0.071	56.1
Weather	Nonroad	0.067	47.7	0.059	47.2
func_cls	Road	0.063	45.1	0.058	46.1
drv_sex	Nonroad	0.024	17.4	0.017	13.1
drv_rest	Nonroad	0.043	30.5	0.039	31.0
Vehtype	Nonroad	0.092	65.6	0.090	72.0
dir_curv	Road	0.032	23.2	0.028	22.1
dir_grad	Road	0.020	14.2	0.019	15.1
drv_age	Nonroad	0.117	83.4	0.113	90.0
Vehyr	Nonroad	0.140	100.0	0.126	100
curv_ang	Road	0.047	33.5	0.045	35.4
pct_grad	Road	0.056	40.1	0.052	41.3
deg_curv	Road	0.035	25.1	0.032	25.4
curv_rad	Road	0.040	28.4	0.034	26.8