Davidson-Luce model for multi-item choice with ties

This paper introduces a natural extension of the pair-comparison-with-ties model of Davidson (1970, J. Amer. Statist. Assoc.), to allow for ties when more than two items are compared. Properties of the new model are discussed. It is found that this "Davidson-Luce" model retains the many appealing features of Davidson's solution, while extending the scope of application substantially beyond the domain of pair-comparison data. The model introduced here already underpins the handling of tied rankings in the "PlackettLuce" R package.