“…The control group is the object that has not been affected by the policy, the treatment group is the object affected by the policy, and then the policy is implemented by changing the two groups of experiments accordingly. In recent years, many studies have used this method to evaluate the emission reduction effect of the emissions trading policy [45][46][47]. In this study, we use 11 provinces and municipalities (Hebei, Henan, Hubei, Hunan, Jiangsu, Zhejiang, Tianjin, Chongqing, Inner Mongolia, Shanxi, and Shaanxi) that piloted emissions trading in 2007 as treatment groups, and then employe propensity score matching (PSM) to match the remaining 18 provinces as control groups.…”