变量

(1)

(2)

(3)

(4)

Upgrade

Treat × Time

0.033

0.110^***

0.061^**

0.120^***

(0.87)

(4.07)

(2.20)

(3.04)

Constant

−2.001^***

−2.838^***

−2.496^***

−2.659^***

(−4.84)

(−8.92)

(−8.71)

(−6.27)

Observations

5,934

11,308

11,099

6,143

Adjusted R-squared

0.771

0.699

0.767

0.731

Control_Var

YES

YES

YES

YES

AreaFE

YES

YES

YES

YES

YearFE

YES

YES

YES

YES