Research on the Nonlinear Impact of Environmental Regulation on the Efficiency of China’s Regional Green Economy: Insights from the PSTR Model

Table 4

Parameter estimation results of panel smoothing threshold regression model.

Variable name	Linear part	Nonlinear part
ERI	3.9845	−6.3490
ES	−3.1238	5.9981
UR	2.4938	−7.2239
FDI	4.6732	−18.3469
Location parameter		0.6129
Smoothing parameter		17362

Note., , and represent the significance level of 1%, 5%, and 10%, respectively.