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. 2019 Feb 8;14(2):e0211963. doi: 10.1371/journal.pone.0211963

Table 2. Gravity model OLS regression results.

Variables Material Plasma Device Diagnostics Simulation
ln(Pm,j) 0.497***
(0.033)
0.508***
(0.032)
0.411***
(0.030)
0.438***
(0.033)
0.488***
(0.033)
ln(Pn,j) 0.497***
(0.033)
0.508***
(0.032)
0.411***
(0.030)
0.438***
(0.033)
0.488***
(0.033)
ln(dmn) -0.495***
(0.044)
-0.451***
(0.040)
-0.464***
(0.042)
-0.546***
(0.049)
-0.485***
(0.043)
cmn,j -0.133
(0.222)
-0.911***
(0.284)
-0.949***
(0.232)
-0.690***
(0.175)
-0.027
(0.194)
Observations 3518 3518 3518 3518 3518
R2 0.113 0.123 0.101 0.094 0.107

Standard error is in parenthesis.

Fixed time effects are included.

* p-value < 0.1,

** p-value < 0.05,

*** p-value < 0.01