Research on the Influence of Emission Trading System on Enterprises' Green Technology Innovation

Table 4

Heterogeneity of patent natures and enterprise natures.

Variable	(1)	(2)	(3)	(4)
	Green patent	Green utility model patents	Non-state-owned enterprises	State-owned enterprises
did	1.3198	0.3605	−1.5346	2.0282
	(0.4112)	(0.2665)	(0.6648)	(0.4060)
Treat	−2.7290	−1.3860	−0.0218	−3.1195
	(0.6465)	(0.4302)	(0.9073)	(0.7532)
Post	0.9545	2.6131	16.8917	0.5431
	(0.5029)	(0.2878)	(13.2532)	(0.5702)
Control variable	Controlled	Controlled	Controlled	Controlled
Time fixed effect	Controlled	Controlled	Controlled	Controlled
Region fixed effect	Controlled	Controlled	Controlled	Controlled
N	13515	13515	6341	7174
R^2	0.6462	0.4075	0.3682	0.7484