Journal of Environmental and Public Health

Research Article

Building Better Cities: Evaluating the Effect of Circular Economy City Construction on Air Quality via a Quasi-Natural Experiment

Table 3

The estimation results based on the PSM-DID method.
VariablesAir quality
Year-by-year matchingNeighboring 1 : 1 matchingNeighboring 1 : 2 matchingNeighboring 1 : 3 matching
(1)(2)(3)(4)
(0.7023)(0.9673)(0.8157)(0.7706)
Weather control variablesYesYesYesYes
City control variablesYesYesYesYes
City-fixed effectsYesYesYesYes
Year-fixed effectsYesYesYesYes
Observation1226605818953
R 20.47900.53190.51580.5084
Note: (1) The matching method in Column 1 is the year-by-year matching, and the matching method in Columns 2–4 is the nearest neighbor matching. (2) The control variables are the same as the benchmark regression equation. (3) The symbols , , and represent a significance level of 10%, 5%, and 1%, respectively.