​The trade specialization index compares the net flow of goods (exports minus imports) to the total flow of goods (exports plus imports). 

This index removes bias of high exports values due to significant re-exports activities, thus is more suitable to identify real producers instead of any intermediate traders. 

Trade correlation index is defined as a simple correlation coefficient between economy A and economy B’s trade specialization index. 

The data cover the period 1995-2011 for more than 120 economic/trade groups and over 360 product groups.The update is done twice a year: in June and October.​