On comparing interval numbers

Abstract This paper first presents a brief survey of the existing works on comparing and ranking any two interval numbers on the real line and then, on the basis of this, gives two approaches to compare any two interval numbers. The first one describes a value judgement index along with a discussion on its strength and weakness over the other approaches. This index has also been called an optimistic decision maker's preference index. The other approach defines strict and fuzzy preference ordering between any two interval numbers from a pessimistic decision maker's point of view. Choice of different decision makers with different degrees of pessimism has also been considered.