TSC = [E.sub.ij] - [I.sub.ij] / [E.sub.ij] + [I.sub.ij] Where i is a country, j is a commodity, E represents exports, I represents imports, TSC index could only be set within range of values, which are between -1 and 1.If TSC>0, then the country i belongs net export country of commodity j, and has strong competition on exporting commodity j.