A Procedure for Facilitating an Expert’s Judgements on a Set of Rules

Abstract

A knowledge structure that is known to be a formal basis for a system assessing students’ knowledge is constructed from an expert’s judgements. Such judgements refer to a body of questions from a specified field, and represent the information concerning which of these questions may be asked, and which can be considered redundant, depending on the answers given by a student during the assessment procedure. The expert’s judgements therefore select rules of the form: “if a student has answered all questions of this subset of questions incorrectly, then do not ask this specific question.”

The selection of the appropriate rules by an expert causes the following problems: firstly, the number of possible judgements grows exponentially with the size of the set of questions under consideration; secondly, contradictory judgements may eventuate, and, thirdly, the number of questions in the conditional part of the rules may be too large to permit a reliable judgement.

This paper therefore suggests a procedure for restricting the expert’s judgements to those that do not logically follow from previous judgements. Contradictory judgements are avoided, and the number of questions in the conditional part of the rules to be judged is minimized within specific equivalence classes. This procedure is appropriate for use within an interactive system for supporting an expert when selecting rules.

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