Laddering: technique and tool use in knowledge acquisition

Laddering is a structured questioning technique derived from the repertory grid technique, enabling a hierarchy of concepts to be established. Previous empirical studies have demonstrated its utility for knowledge elicitation in two classificatory domains. In this paper, three experimental studies of laddering are described. In experiment 1, the technique was used in another classificatory domain, metallic corrosion, and the effects of repeated exposure to the technique and feedback, in the form of Pseudo-English Production Rules, were investigated. These variables had no effect on the productivity of the technique. Experiment 2 compared the laddering technique with three other techniques in a medical diagnostic domain. As in previous studies laddering was found to be the most productive technique despite the change in the type of domain about which knowledge was elicited. In experiment 3, the preferences of subjects interviewed using two versions of the laddering technique, "textual" and "graphical", were compared with those obtained when the subjects were interviewed using a computerised laddering tool. Although the "gain" obtained in the three conditions varied, the group of subjects did not prefer one type of laddering to another. The laddering tool used in the experiment was designed as one tool in an integrated Knowledge Engineering Workbench (KEW). The potential for synergy between the laddering tool and other knowledge acquisition techniques implemented within KEW is explored. Guidance and advice concerning the appropriate context to employ laddering within the knowledge acquisition process is provided.