The GFP list makes use of over 50 factors in our in-house formula to determine a given nation's Power Index ("PwrIndx") score. This provides the final ranking while also allowing smaller, more technologically-advanced, nations to compete with larger, lesser-developed ones. Some bonuses and penalties are added for refinement that, in the end, we hope presents an unbiased look into the potential conventional military strength of a world power.
There are a total of (9) countries of Southeast Asia represented in the GFP database.
Sources: CIA.gov, CIA World Factbook, wikipedia.com, public domain print and media sources and user contributions. Some values may be estimated when official sources are lacking.