变量

OLS模型

随机前沿引力模型(SFA)

时变模型

非时变模型

常数

788.319

(727.302)

788.853***

(0.999)

789.000***

(1.024)

PGDP_it

3.693

(2.539)

4.653***

(0.209)

3.574***

(0.179)

PGDP_jt

1.133***

(0.066)

1.654***

(0.166)

1.330***

(0.205)

POP_it

−38.943

(35.622)

−40.537***

(0.383)

−39.007***

(0.454)

POP_jt

1.394***

(0.040)

1.903***

(0.111)

1.479***

(0.125)

DIS_ij

−1.715***

(0.315)

−0.021

(0.889)

−1.769

(1.176)

σ²

0.375

1.420***

(0.143)

0.545

(0.565)

γ

—

—

0.957***

(0.008)

0.845***

(0.159)

μ

—

—

2.331***

(0.657)

0.811

(0.846)

η

—

—

−0.039***

(0.007)

—

—

对数似然值

-108.273

−30.808

−40.625

LR检验

—

154.930

135.297