Table 4 Results of the stochastic frontier gravity model
From: Effects of free trade on export efficiency of COMESA member-states
Dependent variable ln(exports) | Baseline model | Robustness | ||||
|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | |
Stochastic frontier | ||||||
ln GDPit | 1.024*** | 1.019*** | 0.953*** | |||
(0.035) | (0.035) | (0.033) | ||||
ln GDPjt | 0.721*** | 0.719*** | 0.694*** | |||
(0.027) | (0.027) | (0.026) | ||||
ln Distij | − 2.17*** | − 2.166*** | − 2.018*** | − 1.538*** | − 1.545*** | − 1.512*** |
(0.078) | (0.077) | (0.072) | (0.078) | (0.077) | (0.076) | |
ln GDPPCit | 0.135*** | 0.151*** | 0.292*** | |||
(0.045) | (0.045) | (0.043) | ||||
ln GDPPCjt | 0.291*** | 0.284*** | 0.228*** | |||
(0.039) | (0.039) | (0.039) | ||||
Constant | − 6.326*** | − 6.213*** | − 5.256*** | 27.193*** | 27.165*** | 26.265*** |
(0.932) | (0.93) | (0.899) | (0.631) | (0.629) | (0.612) | |
Inefficiency model | ||||||
Borderij | − 15.98*** | − 16.003*** | − 17.701*** | − 23.901*** | − 23.942*** | − 25.195*** |
(1.131) | (1.132) | (1.249) | (1.364) | (1.372) | (1.479) | |
Langij | − 2.803*** | − 2.784*** | − 3.639*** | − 0.87*** | − 0.84*** | − 1.424*** |
(0.268) | (0.269) | (0.294) | (0.269) | (0.27) | (0.279) | |
COMESAfta | − 1.082*** | − 0.272 | − 2.047*** | − 0.564 | ||
(0.262) | (0.428) | (0.27) | (0.457) | |||
Regqualij | − 0.162*** | − 0.144*** | − 0.143*** | − 0.111*** | ||
(0.008) | (0.011) | (0.008) | (0.011) | |||
COMESAfta*regqual | − 0.033** | − 0.12*** | − 0.057*** | − 0.123*** | ||
(0.014) | (0.008) | (0.014) | (0.008) | |||
Constant | 10.64*** | 10.145*** | 7.338*** | 11.803*** | 10.865*** | 8.412*** |
(0.308) | (0.378) | (0.316) | (0.36) | (0.443) | (0.343) | |
Observations | 8525 | 8525 | 8525 | 8525 | 8525 | 8525 |
Chi2 | 1610.002 | 1613.797 | 1731.785 | 425.152 | 428.708 | 426.136 |
Likelihood ratio | − 25,432.31 | − 25,429.44 | − 25,576.66 | − 26,514.79 | − 26,506.63 | − 26,580.23 |