Is the High-Speed Rail Opening Environmentally Friendly? Taking the Difference-in-Differences Test in Jiangsu, China

Table 1

Statistical description of major variables.

Variables	Economic meaning	Unit	Sample	Mean	Standard deviation	Minimum	Maximum
Goodday	Days of air quality reaching the second order (good)	Day	234	287.269	61.647	145	362
G	High-speed railway opening virtual variable	—	234	0.163	0.370	0	1
PGDP	GDP/total population	Yuan	234	45201.160	34380	3993	145556
T3	Third industry added value	Billion Yuan	234	39.150	5.962	26.8	58.390
PI	Per capita disposable income of urban residents	Yuan	234	19403.620	11226.790	4617	54341
FDI	Actual use of foreign direct investment	Billion Yuan	234	0.044	0.030	0.004	0.201
U	Urban population/total population	%	234	0.532	0.164	0.137	0.980