Gravity-model estimation with binary network variables.

Full-sample (pooled) ordinary least-square (OLS) fit. Years y = 1960, …, 2000. Dependent variable: logs of total bilateral trade ${\tau }_{ij}^y=t_{ij}^y+t_{ji}^y$. Country-year dummy variables for importer/exporter effects and constant included. Explanatory variables: See main text. WD (p-val): Wooldridge-Drukker F-test for serial correlation in linear panel-data models (p-value) [41, 42]. Significance levels: *** = 1%, ** = 5%, * = 10%