Table 2.

Grey linguistic scale (Cui et al., 2019).

Linguistic levels	Grey numbers
No influence (NI)	[0.00, 0.00]
Very low influence (VLI)	[0.00, 0.25]
Low influence (LI)	[0.25, 0.50]
High influence (HI)	[0.50, 0.75]
Very high influence (VHI)	[0.75, 1.00]