Introduction

At the heart of psychological and economic theories of consumer choice behaviour lie implicit or explicit assumptions about regularities (i.e., consistencies) in evaluation processes and decision rules across individuals, product classes, time periods, cultures, etc. Demonstrating the existence of such regularities is a crucial step in establishing the external and cross validity of SP theory and methods, but there are also two broader reasons to seek regularities in consumer choices:

1. To provide support for psychological and economic theories of choice in a variety of contexts of interest to academic disciplines interested in and practitioners of choice modelling; and

2. To support the development and generalisability of theory dealing with specific, substantive empirical issues.

The purpose of this chapter is to describe and provide a theoretical rationale for seemingly fairly widespread empirical regularities in published and unpublished research on the analysis and modelling of preferences and choices. In particular, we provide evidence that theory discussed in previous chapters (especially chapter 8) predicts that a simple behavioural mechanism can explain a wide range of empirical comparisons of preference and choice models estimated from different conditions, contexts, times, geographical location and/or product classes. In this chapter our objective is to explain this mechanism, demonstrate how it arises naturally as a consequence of random utility theory and illustrate its generality in a wide range of empirical contexts.