variable

(1)

Do not control the supplier

(2)

lnCost

(3)

lnCost

Constant

0.019***

0.019***

0.019***

(3.55)

(3.54)

(3.52)

lnRev

0.941***

0.942***

0.942***

(66.38)

(66.34)

(66.43)

D

−0.033***

−0.035***

−0.034***

(−3.70)

(−3.85)

(−3.83)

lnRev * D

−0.195**

−0.235***

−0.230***

(−2.54)

(−2.98)

(−2.93)

SP * lnRev * D

0.023***

(2.86)

SP * lnRev

0.002

(0.96)

SP * D

−0.006*

(−1.77)

SPSC * lnRev * D

0.001***

(2.84)

SPSC * lnRev

0.000

(0.68)

SPSC * D

−0.000**

(−2.38)

AI

−0.002

−0.002

−0.002

(−1.16)

(−1.16)

(−1.16)

AI * lnRev * D

0.007

0.007

0.007

(0.85)

(0.87)

(0.84)

AI * lnRev

−0.023***

−0.023***

−0.023***

(−4.16)

(−4.14)

(−4.10)

AI * D

0.010***

0.009***

0.009***

(3.32)

(3.27)

(3.28)

EI

−0.742***

−0.749***

−0.748***

(−2.68)

(−2.71)

(−2.70)

EI * lnRev * D

−5.445***

−5.421***

−5.388***

(−3.19)

(−3.18)

(−3.16)

EI * lnRev

0.888

0.893

0.866

(0.96)

(0.97)

(0.94)