$\Delta D_{it}=\alpha +\beta DE{F}_{it}+{\epsilon }_{it}$

sample 1

(1)

sample 2

(2)

sample 3

(3)

β

0.219667***

(0.0000)

0.313093***

(0.0000)

0.353369***

(0.0000)

N

960

960

584

R²

0.204101

0.31342

0.720028

F-test

245.6711***

437.3210***

1496.777***