Abstract
The importance of properly specifying choice sets to avoid biased parameters is well recognized in the literature and it is particularly relevant for spatial choice models where alternatives are generally numerous and somewhat artificially defined (i.e. traffic zones). The choice set refers to the set of discrete alternatives considered by an individual in the decision-making process which is a subset of the universal choice set that consists of all alternatives available to the decision-maker. The objective of this paper is to review the various approaches that have been suggested to model such set formation. Strengths and weaknesses of each of these approaches are discussed.