Variable name

(1) IPG1

(2) IPG2

(3) IPG1

(4) IPG2

TFP _OP

SGR

IPG

0.0246***

0.0148***

0.00180***

0.00106***

(16.08)

(15.70)

(9.20)

(8.82)

IPG²

−0.0000966***

−0.0000355***

−0.00000894***

−0.00000319***

(−10.24)

(−9.98)

(−7.56)

(−7.17)

Constant

13.86***

13.93***

−0.257***

−0.255***

(29.45)

(29.54)

(−5.16)

(−5.11)

Control

Yes

Yes

Yes

Yes

Year

Yes

Yes

Yes

Yes

Sample size

5260

5260

5260

5260

adj.R²

0.280

0.277

0.049

0.048