Evaluating students’ answerscripts based on interval-valued fuzzy grade sheets

In this paper, we propose two new methods for evaluating students’ answerscripts based on interval-valued fuzzy grade sheets. The marks awarded to the answers in the students’ answerscripts are represented by interval-valued fuzzy sets. Each element in the universe of discourse belonging to an interval-valued fuzzy set is represented by an interval between zero and one. The degree of similarity between an interval-valued fuzzy mark and a standard interval-valued fuzzy set is calculated by a similarity function. An index of optimism λ determined by the evaluator is used to indicate the degree of optimism of the evaluator, where λ ∈ [0, 1]. The experimental results show that the proposed methods are more stable than Biswas’s method for students’ answerscripts evaluation. They can evaluate students’ answerscripts in a more flexible and more intelligent manner.