. This indicates economies of scale and promotes the country to trade more with foreign partners in a wider range of
goods. Distij measures the great-circle distance between the capital cities (or economic centres) of countries i and j. As the geographical
distance is used to proxy for transportation and communication costs, as well as required delivery time, its sign should be negative. Two
binary variables namely sharing a common border (Adjij) and speaking the same language (Langij) are also included as regressors.
Finally, uijt is assumed to be a log-normally distributed error term