Global Trade in Goods
The global trade in goods is known as merchandise trade and 2 classifications exist: general trade and special trade. The corresponding special trade figures or numbers are lower because they exclude certain trade flows such as those goods passing through customs bonded warehouses and those passing through special economic zones (mostly through export processing zones and free trade zones). There is an inherent difficulty in fully accounting for the total trade in goods because of fluctuations in the major currencies used for payments. The disparities could result from using official exchange rates rather than the real market-based exchange rates. To partially solve this problem, some economists use an alternative system of weights to compute for the total value of world trade called purchasing power parities (PPP). This is to smoothen out (attenuate) certain distortions linked in using different currencies. Products have 3 main classifications: primary products (both agricultural and mining products), manufactures (such as textiles, shoes, clothing, steel, automotive products, and most consumer goods) and other products (commodities not included in the 2 other classifications such as gold, firearms and ammunitions). For a detailed listing of all product classifications, please visit this site:
http://www.wto.org/english/res_e/statis_e/technotes_e.htm
Alternatively, information on trade in a particular commodity can also be obtained by using Duke University’s computerized database up to the 4th level of detail using the Standard International Trade Classification (SITC) at this site:
http://library.duke.edu/research/help/databases/guides/wta/