Preference reversals: Violations of unidimensional procedure invariance.

Abstract

Preference reversals have usually been explained by weighted additive models, in which different tasks give rise to different importance weights for the stimulus attributes, resulting in contradictory trade-offs. This article presents a preference reversal of a more extreme nature. Let (10, 5 Migr) denote living 10 years with a migraine for 5 days per week. Many participants preferred (10, 5 Migr) to (20, 5 Migr). However, when asked to equate these two options with a shorter period of good health, they usually demanded more healthy life years for (20, 5 Migr) than for (10, 5 Migr). This preference reversal within a single dimension cannot be explained by different importance weights and suggests irrationalities at a more fundamental level. Most participants did not change their responses after being confronted with their inconsistencies.

A Consistency Test of the Time Trade-Off

“…Constant proportional tradeoffs implies that the time trade-off utility is independent of the gauge duration in the elicitation. Several studies find support for constant proportional trade-offs (Pliskin, Shepard, and Weinstein, 1980, Hall et al, 1992, Stalmeier, Wakker, and Bezembinder, 1997, Dolan and Stalmeier, 2003. Sackett and Torrance (1978) found negative evidence.…”

In search of a preferred preference elicitation method: A test of the internal consistency of choice and matching tasks

“…The differences between choice and matching elicitation tasks have been investigated before (Bostic et al, 1990;Huber et al, 2002;Loomes, 1988;Stalmeier et al, 1997). The major conclusion from these studies was that elicitation of indifferences by means of choices 1 Recently, however, (Butler and Loomes, 2007) and (Schmidt and Hey, 2004) casted doubt on the validity of the scale compatibility hypothesis and suggested that preference reversals are partly caused by a higher error yields better results than indifferences obtained by matching, in the sense that series of choices generated fewer inconsistencies than matching questions (Bostic et al, 1990),…”

The QALY Model and Individual Preferences for Health States and Health Profiles over Time: A Systematic Review of the Literature

“…However, since there are an infinite number of such 13 combinations of health states, establishing the benchmark value of each in QALY terms 14 would be quite impractical, and some simplifying assumptions are introduced. 15 16 In this paper, we present the results from a systematic review of the literature that was 17 designed to examine the extent to which people's preferences satisfy some of the key 18 assumptions of the QALY model explained below. Our aim has not been to be prescriptive 19 about which elements of the QALY approach should be adhered to, and we leave it for others 20 to make their judgements about the normative significance of some of our findings.…”