[Retracted] Environmental Efficiency of Node Cities in Chinese Section of Silk Road Economic Zone and Its Influencing Factors

Table 5

Tobit regression results.

Independent variables	Meaning	Coefficient	Standard error	Z-score	Significance
Ln (GP)	Logarithm of per-capita GDP	0.144	0.037	3.835
GR	Regional GDP as a proportion of national GDP	−0.015	0.719	−0.021	—
PI	Secondary industry output as a proportion of regional GDP	−0.210	0.204	−1.030	—
FI	Regional industrial pollution management investment as a proportion of regional GDP	−7.869	6.156	−1.283	—
DT	Trade dependence	0.312	0.055	5.674
DC	Foreign fund dependence	−0.357	0.698	−0.512	—
Ln (TI)	Technological progress	−0.126	0.020	−6.257
Ln (PD)	Logarithm of population density	0.057	0.013	4.253
C	Constant	1.042966	0.09519	10.95632