Effect of type-2 fuzzy membership function shape on modelling variation in human decision making

This paper explains how the shape of type-2 fuzzy membership functions can be used to model the variation in human decision making. An interval type-2 fuzzy logic system (FLS) is developed for umbilical acid-base assessment. The influence of the shape of the membership functions on the variation in decision making of the fuzzy logic system is studied using the interval outputs. Three different methods are used to create interval type-2 membership functions. The centre points of the primary membership functions are shifted, the widths are shifted, and a uniform band is introduced around the original type-1 membership functions. It is shown that there is a direct relationship between the variation in decision making and the uncertainty introduced to the membership functions.