Dependent Variable: TFP

(1)

(2)

(3)

(4)

DID

−0.0844***

−0.0598***

(0.0133)

(0.0146)

DDD

−0.0905***

−0.0753***

(0.0116)

(0.0122)

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

0.2004

0.1378

0.1589

0.1321