Special Unfolding Models

  • Ingwer Borg
  • Patrick Groenen
Part of the Springer Series in Statistics book series (SSS)


In this chapter, some special unfolding models are discussed. First, we distinguish internal and external unfolding. In the latter, one first derives an MDS configuration of the choice objects from proximity data and afterwards inserts ideal points to represent preference data. Then, the vector model for unfolding is introduced as a special case of the ideal-point model. In the vector model, individuals are represented by vectors and choice objects as points such that the projections of the objects on an individual’s vector correspond to his or her preference scores. Then, in weighted unfolding, dimensional weights are chosen freely for each individual. A closer investigation reveals that these weights must be positive to yield a sensible model. A variant of metric unfolding is discussed that builds on the BTL choice theory.


Ideal Point Vector Model Object Point Dimension Weight Preference Judgment 
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Copyright information

© Springer Science+Business Media New York 1997

Authors and Affiliations

  • Ingwer Borg
    • 1
  • Patrick Groenen
    • 2
  1. 1.Zentrum für Umfragen, Methoden und AnalysenMannheimGermany
  2. 2.Department of Data TheoryLeiden UniversityLeidenThe Netherlands

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