由于系统因素之间关系非常复杂，特别是其表面现象及变化的随机性、模糊性和灰色性，使人们在观察、分析、预测和决策时得不到足够的信息，找不到主要矛盾，从而给复杂系统的系统分析带来困难。这就需要灰色关联分析。-Because the system is very complex relationship between factors, especially changes in the surface phenomena and random, fuzzy and gray so that people in the observation, analysis, forecasting and decision-making can not get enough information, can not find the main contradictions thus to the complex system of systems analysis difficult. This requires gray relational analysis.