Dependent Variable: TFP

(1)

(2)

(3)

(4)

DID

−12.4899***

−10.1866***

(1.2888)

(1.4123)

DDD

−12.4367***

−10.8520***

(1.1216)

(1.1732)

Control variables

No

Yes

No

Yes

County fixed effect

Yes

Yes

Yes

Yes

Year fixed effect

Yes

Yes

Yes

Yes

Observations

1920

1920

1920

1920

R-squared

0.1651

0.1271

0.1101

0.1052