At the time of publication Chandra R. Bhat and Marisol Castro were at the University of Texas at Austin, and Abdul Rawoof Pinjari was at the University of South Florida.Many consumer choice situations are characterized by the simultaneous demand for multiple
alternatives that are imperfect substitutes for one another, along with a continuous quantity
dimension for each chosen alternative. To model such multiple discrete-continuous choices, most
multiple discrete-continuous models in the literature use an additively-separable utility function,
with the assumption that the marginal utility of one good is independent of the consumption of
another good. In this paper, we develop model formulations for multiple discrete-continuous
choices that allow a non-additive utility structure, and accommodate rich substitution structures
and complementarity effects in the consumption patterns. Specifically, three different nonadditive
utility formulations are proposed based on alternative specifications and interpretations
of stochasticity: (1) The deterministic utility random maximization (DU-RM) formulation, which
considers stochasticity due to the random mistakes consumers make during utility maximization;
(2) The random utility deterministic maximization (RU-DM) formulation, which considers
stochasticity due to the analyst’s errors in characterizing the consumer’s utility function; and (3)
The random utility random maximization (RU-RM) formulation, which considers both analyst’s
errors and consumer’s mistakes within a unified framework. When applied to the consumer
expenditure survey data in the United States, the proposed non-additively separable utility
formulations perform better than the additively separable counterparts, and suggest the presence
of substitution and complementarity patterns in consumption.Civil, Architectural, and Environmental Engineerin
