The Impact of Truck Proportion on Traffic Safety Using Surrogate Safety Measures in China

Table 4

The relationship among indicators of traffic flow parameters in partial correlation analysis.

Variables (truck proportion) (min)	Evaluation indexes (other variables controlled)	85%V–15%V	Variation coefficient	Number of lane changes
5	The correlation	−0.511	0.523	0.006
	Significance (bilateral)	0.000	0.000	0.862
	.df	728	728	728
10	The correlation	−0.590	0.595	0.033
	Significance (bilateral)	0.000	0.000	0.537
	.df	361	361	361
15	The correlation	−0.551	0.582	0.044
	Significance (bilateral)	0.000	0.000	0.492
	.df	247	247	247

a: the cell contains a zero-order correlation (Pearson). Significant at the 0.05 level.