Footnote [23]:
"Threshold 21" is a systems dynamics simulation modeling program for policy analysis of national sustainable development with environmental protection. It is a user friendly PC-based model that enables decision-makers to assess the long-term (50 - 100 years) effects of alternative investment, tax, subsidy, other relative price factors on national development indicators. Social, economic, and environmental implications are analyzed endogenously. It includes sectors for demography, health care, education, nutrition, goods, trade, agriculture, fuel resources, energy, pollution, military, technology, debt, national accounts, and "rest of world". It is for policy analysis and crisis management to train would-be decision makers for win-win cooperation.

The Systems Dynamics methodology was originated by Professor Jay Forrester of Massachusetts Institute of Technology. The main purpose of the methodology is not on the forecasting capability of the simulation model, but rather on the analytical understanding with rational and critical thinking basing on reliable facts and figures, of the interwoven and interdependent relations among various societal factors.