Biplots of free-choice profile data in generalized orthogonal Procrustes analysis

Free-choice profiling is a technique that is used in sensory studies whereby assessors are allowed to describe products by using their own preferred descriptors and own number of descriptors. We show how a study of this type on eight varieties of port wine can be analysed and, in particular, how to associate the descriptors of the wines with each assessor and with a group average representation. We show how biplots combined with generalized orthogonal Procrustes analysis can be constructed and used to explore consistencies and idiosyncrasies among assessors' uses of their descriptors and scales. Copyright 2007 Royal Statistical Society.