ip

(1)

(2)

(3)

(4)

er

−0.270***

(0.046)

−0.245***

(0.046)

−0.203***

(0.043)

−0.195***

(0.042)

rii

−2.607***

(0.533)

−2.541***

(0.521)

−2.373***

(0.485)

−2.161***

(0.469)

fta

0.001***

(0.0003)

0.001***

(0.0003)

0.002***

(0.0003)

0.002***

(0.0003)

er*rii

8.091***

(2.057)

7.701***

(2.028)

6.784***

(1.919)

5.536***

(1.831)

er*fta

0.001

(0.002)

0.0002

(0.002)

−0.0002

(0.002)

0.001

(0.001)

er*rii*fta

0.034

(0.038)

0.055**

(0.027)

0.078***

(0.025)

0.087***

(0.028)

Control variable

control

control

control

control

Time

control

control

control

control

Product

control

control

control

control