Could the Construction of Sustainable Development Pilot Zones Improve the Urban Environment Efficiency in China?

Table 2

The impact of the construction of sustainable development pilot zone on environmental efficiency.

	Environmental efficiency
	Model I	Model II	Model III
DID	—	0.274	0.277
Environmental regulation index	0.272	—	0.2451
Science and technology input	0.096	—	0.1043
Proportion of the secondary industry	0.582	—	0.2669
GDP per capita	−5.047	—	0.262
Quadratic GDP per capita	0.252	—	—

Note: , , and represent significance levels of 10%, 5%, and 1%, respectively.