“The repertory grid task confronts the consumer with triads of product alternatives… The respondent is asked to indicate which two stimuli are most alike and on which attribute(s) they differ from the third stimulus. This procedure is repeated for different triads until the attributes of the respondent are exhausted or all brands have been included.”
“Steenkamp, J.-B.E.M., van Trijp, H.C.M., 1997. Attribute Elicitation in Marketing Research: A Comparison of Three Procedures. Marketing Letters 8, 153–165.