(1)

(2)

(3)

(4)

国有企业

非国有企业

中下游

上游

截距

−346.796^**

−134.541^**

−127.171

−76.974^**

IE

10.94^*

20.568^**

9.537^*

6.026^**

ln(size)

69.675^**

19.991^*

25.283

14.243^*

pb

9.893^**

8.431^**

7.230^*

9.377^**

np

−0.039

0.089

0.154

0.01

tret

−2.174^*

6.958

3.04

−0.481

lev

−1.225^**

−0.602

−0.439^*

−0.256

R²

0.942

0.988

0.949

0.978

R² (within)

0.922

0.964

0.910

0.965

F

551.929

20.438

255.379

343.199

检验

p = 0.000

p = 0.000

p = 0.000

p = 0.000