Izvorni znanstveni članak
https://doi.org/10.1080/1331677X.2020.1782764
Extending synthetic control method for multiple treated units: an application to environmental intervention
Juying Zeng
orcid.org/0000-0002-0943-6797
Ruyu Zhao
Weidong Dai
Sažetak
Taking the environmental interventions on air quality at G20
Hangzhou Summit as a natural experiment, this paper innovatively establishes an extended synthetic control method with multiple units to evaluate the dynamic treatment effects on air
quality improvement at the Summit. The method constructs datadriven weights according to the fluctuation of urban air quality to
obtain a more robust and stable estimation with smaller root
mean squared prediction error (RMSPE). By minimising RMSPE for
pre-intervention model fitting, the study takes nine cities under
policy intervention in Zhejiang as treatment cities, and 45 key cities without policy intervention as control cities during
201501–201706 as the final improved experimental scheme. The
policy effect of environmental regulations on the average
monthly air quality composite index of treated cities in Zhejiang
is -0.84 during 201607–201702; while no significant treatment
effect is observed since 201702. The results indicate that the
environmental policy for the G20 Hangzhou Summit lasted a relatively short period, and it had a significant short-term improvement effect while losing its long-term improving effect on air
quality in treated cities. The identification validates the extended
synthetic control method with multiple units could also be
applied to the policy effect evaluation in other areas.
Ključne riječi
Extended synthetic control method; multiple treated units; environmental regulation; air quality index; G20 Hangzhou Summit
Hrčak ID:
301166
URI
Datum izdavanja:
31.12.2021.
Posjeta: 228 *