“…Meanwhile, GATT/WTO reasoned that "as long as a regional trade agreement adheres to trade liberalization progress, their regional preferential policies can be maintained and applied only to the same RTA member countries and not to any non-member countries, no matter if those non-member countries are WTO members or not". Previously, many studies attempted to find out the effect of trade liberalization on bilateral or multilateral trade, such as Sapir (2001), Robert (2005), Clausing (2001), Magee (2008), Wahyudi et al (2017), Korinek et al (2009) Adam et al (2003, Krugman et al (2003), Kyoji et al (2002), Joung et al (2006), Romalis (2007), Khadan et al (2016), Bojnec and Ferto (2012). Meanwhile, the trade literature not only focuses on the total exports or value but also on the dual margin of trade in the case of trade liberalization see Krugman (1979Krugman ( , 1980, Rivera-Batiz-Romer (1991), Eaton and Kortum (2002), Melitz (2003), Bernard et al (2003), Nocke and Yeaple (2006), Broda et al (2006), Chaney (2008), Arkolakis and Muendler (2010), Melitz and Redding (2015), Arkolakis et al (2012), Lionel (2015), Mayer et al (2014), andFelbermayr et al (2015).…”