Sectoral exports (dependent variable) are from UNCTAD database and are in
thousand US $. FTA_1 is a dummy variable that takes the value of 1 when countries i and j are members of the FTA in year t, zero otherwise. FTA_2 is a dummy variable that
takes the value of 1 when country i is a member of the FTA and j is not in year t, zero otherwise. FTA_3 is a dummy variable that takes the value of 1 when country i is not a
member of the FTA and j is a member in year t, zero otherwise.