Helpman, Melitz and Rubinstein (2008) derive gravity equations to estimate effects of trade barriers on the intensive and extensive margins of trade. They exploit the frequency of zeros in aggregate bilateral trade data to identify effects on the extensive margin and to obtain controls for firm...

Measured by trade in intermediate inputs, economic integration has increased between 2000 and 2014 between members of the European Union and even more with non-members. Integration is negatively related to economic size and positively to the number of years as a member. Germany is the largest...