⁵In a general equilibrium analysis, if there are some countries that found the trade balance to improve, it must logically have deteriorated in others. Global general equilibrium gravity models that have this property are actually very rare, but see e.g. Bikker (1987). The studies in our meta-sample are all partial analyses concerned with a limited number of origin and destination countries and a rectangular rather than square trade matrix. In that case, the empirical evidence shows that, ceteris paribus, an increase in infrastructure improves the trade balance in the countries concerned.