Does Airport Preferential Policy Aggravate the Competition of Aviation Hubs in Central and Western China? Based on the Investigation of 78 Airports

Table 6

The mechanism test of preferential policy.

	(1)	(2)	(3)
D	0.0651	10.3513	1.1473
	(1.90)	(9.29)	(9.12)
lntra	0.0283	0.0284	0.0288
	(1.47)	(1.47)	(1.49)
lncm	0.0232	0.0232	0.0227
	(1.35)	(1.35)	(1.32)
lnrf	−0.0256	−0.0256	−0.0256
	(−1.51)	(−1.51)	(−1.51)
gov	−0.0436	−0.0436	−0.0435
	(−2.90)	(−2.90)	(−2.89)
lnta	0.0839	0.0839	0.0842
	(2.74)	(2.74)	(2.74)
lnpop	0.4652	0.4664	0.4749
	(3.82)	(3.83)	(3.92)
pd	0.1787	0.1891	0.2546
	(0.19)	(0.20)	(0.28)
esis	−0.0976	−0.1002	−0.1179
	(−0.35)	(−0.36)	(−0.42)
sec	0.0118	0.0118	0.0119
	(5.13)	(5.14)	(5.19)
lntea	0.0546	0.0549	0.0547
	(1.56)	(1.58)	(1.57)
proad	0.0045	0.0045	0.0045
	(1.09)	(1.09)	(1.09)
Dxlntea		−0.9480
		(−9.17)
Dxsec			−0.0221
			(−8.56)
Provincial effect	Yes	Yes	Yes
Time effect	Yes	Yes	Yes
_cons	11.1517	11.1411	11.0849
	(14.52)	(14.52)	(14.47)
R ^2	0.971	0.971	0.971
N	1404	1404	1404

t statistics in parentheses. , , and .