Table 1.

Variable settings and descriptive statistics

Category	Variables	Definition	Unit	Data processing	Mean	Std. Dev	Min	Max
Input variables	Total energy consumption		Tons of standard coal	Take logarithm	4.094	0.282	4.617	3.204
	Employment		10,000 people	Take logarithm	3.324	0.339	3.854	2.490
	Fixed asset investment		million RMB	Take logarithm	6.128	0.345	6.771	5.157
Output variables	GDP to SO2 emissions ratio	GDP/SO2 emissions	100 million yuan/10,000 tons	Take logarithm	2.796	0.586	5.270	1.709
Environment variables	Economic structure	Secondary industry added value/GDP			0.440	0.087	0.590	0.162
	Energy consumption structure	Coal consumption/Primary energy			4.611	12.431	96.436	0.265
	Urbanization process	Urban Population/total Population			0.576	0.122	0.896	0.350
	Technology Innovation	R&D investment	million	Take logarithm	6.202	0.584	7.365	4.762