A Hybrid Grey Based KOHONEN Model and Biogeography-Based Optimization for Project Portfolio Selection

Table 2

The concept of black, grey, and white information.

System/specifications	White	Grey	Black
Information	Known	Incomplete	Unknown
Clarity	Clear	Grey	Tunnel
Process	Not new	The old is substituted	New
Trait	Regular	Complicated	Chaos
Methodology	Positive	Transitive	Negative
Trait	Accurate	Bearable	Extremist
conclusion	Single criterion	Multicriteria	Inconclusive