Abstract:
Investigation of the 'rationality' of responses to discrete choice experiments (DCEs) has been a theme of research
in health economics. Responses have been deleted from DCEs where they have been deemed by researchers to
(a) be 'irrational', defined by such studies as failing tests for non-satiation, or (b) represent lexicographic preferences.
This paper outlines a number of reasons why deleting responses from DCEs may be inappropriate after
first reviewing the theory underpinning rationality, highlighting that the importance placed on rationality depends
on the approach to consumer theory to which one ascribes. The aim of this paper is not to suggest that
all preferences elicited via DCEs are rational. Instead, it is to suggest a number of reasons why it may not be the
case that all preferences labelled as 'irrational' are indeed so. Hence, deleting responses may result in the removal
of valid preferences; induce sample selection bias; and reduce the statistical efficiency and power of the estimated
choice models. Further, evidence suggests random utility theory may be able to cope with such preferences.
Finally, we discuss a number of implications for the design, implementation and interpretation of DCEs and
recommend caution regarding the deletion of preferences from stated preference experiments.
