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Violations of the assumptions of complete information [CI] and independence of irrelevant alternatives (IIA) in discrete-choice experiment (DCE) data imply sensitivity of preference estimates to the decision context and the alternatives evaluated. There is a paucity of evidence on how these two assumptions affect health-preference results and whether the usual specifications of random-parameters logit models are sufficient to address these violations. We assessed the appropriateness of these assumptions in a DCE valuating interventions to prevent long-term health problems that could be identified through whole genome sequencing. A DCE survey was administered to members of a nationally representative consumer panel to elicit their preferences for options to reduce the risk of health problems. The treatment options presented (surgery, medication, and watchful waiting) and the context for the decisions elicited (severity and likelihood of the health problem) were varied experimentally to evaluate the sensitivity of preference results to such changes. We find evidence of IIA violations as the options presented to prevent health changed. Our results also are consistent with the expectation that additional substitutes decrease the monetized value of alternatives. We also find some evidence that the decision context can moderate such effects, which constitutes a new finding.

Willingness-to-pay (WTP) estimates derived from discrete-choice experiments (DCEs) generally assume that the marginal utility of income is constant. This assumption is consistent with theoretical expectations when costs are a small fraction of total income. We analyze the results of five DCEs that allow direct tests of this assumption. Tests indicate that marginal utility often violates theoretical expectations. We suggest that this result is an artifact of a cognitive heuristic that recodes cost levels from a numerical scale to qualitative categories. Instead of evaluating nominal costs in the context of a budget constraint, subjects may recode costs into categories such as 'low', 'medium', and 'high' and choose as if the differences between categories were equal. This simplifies the choice task, but undermines the validity of WTP estimates as welfare measures. Recoding may be a common heuristic in health-care applications when insurance coverage distorts subjects' perception of the nominal costs presented in the DCE instrument. Recoding may also distort estimates of marginal rates of substitution for other attributes with numeric levels. Incorporating 'cheap talk' or graphic representation of attribute levels may encourage subjects to be more attentive to absolute attribute levels.

Background: Patient preferences can affect colorectal cancer (CRC) screening test use. We compared utility-based preferences for alternative CRC screening tests from a stated-preference discrete-choice survey of the general population and physicians in Canada and the United States. Methods: General population respondents (Canada, n=501; US, n=1087) participated in a survey with 12 choice scenarios and 9 CRC screening test attributes. Physicians (n=100, both Canada and US) reported expected patient preferences. We estimated relative importance of attributes using bivariate probit regression analysis and calculated willingness-to-pay for various CRC screening tests. Results: In 28 and 31% of scenarios, Canadian and US respondents, respectively, chose no screening over a hypothetical test. Canadian (45%) and US (46%) physicians expected patients to choose no screening more often. For all groups the most important attribute was sensitivity, but physicians' perception of patients' preferences are significantly different from actual preferences. Other key attributes are those related to test performance or the testing process. Fecal DNA, colonoscopy, and virtual colonoscopy were the most preferred tests by all groups, but respondents were willing-to-pay more than physicians predicted. Conclusion: Physicians' perception of patients' preferences are quite different from those of the general population. However, among general population and physicians, Canadian and US preferences were similar. Copyright © 2009 John Wiley & Sons, Ltd.

This study uses stated-preference (SP) analysis to measure willingness to pay (WTP) to reduce acute episodes of respiratory and cardiovascular ill health. The SP survey employs a modified version of the health state descriptions used in the Quality of Well Being (QWB) Index. The four health state attributes are symptom, episode duration, activity restrictions and cost. Preferences are elicited using two different SP formats: graded-pair and discrete-choice. The different formats cause subjects to focus on different evaluation strategies. Combining two elicitation formats yields more valid and robust estimates than using only one approach. Estimates of indirect utility function parameters are obtained using advanced panel econometrics for each format separately and jointly. Socio-economic differences in health preferences are modelled by allowing the marginal utility of money relative to health attributes to vary across respondents. Because the joint model captures the combined preference information provided by both elicitation formats, these model estimates are used to calculate WTP. The results demonstrate the feasibility of estimating meaningful WTP values for policy-relevant respiratory and cardiac symptoms, even from subjects who never have personally experienced these conditions. Furthermore, because WTP estimates are for individual components of health improvements, estimates can be aggregated in various ways depending upon policy needs. Thus, using generic health attributes facilitates transferring WTP estimates for benefit–cost analysis of a variety of potential health interventions. Copyright © 2000 John Wiley & Sons, Ltd.

Patient preferences can affect colorectal cancer (CRC) screening test use. We compared utility-based preferences for alternative CRC screening tests from a stated-preference discrete-choice survey of the general population and physicians in Canada and the United States.General population respondents (Canada, n = 501; US, n = 1087) participated in a survey with 12 choice scenarios and 9 CRC screening test attributes. Physicians (n = 100, both Canada and US) reported expected patient preferences. We estimated relative importance of attributes using bivariate probit regression analysis and calculated willingness-to-pay for various CRC screening tests.In 28 and 31% of scenarios, Canadian and US respondents, respectively, chose no screening over a hypothetical test. Canadian (45%) and US (46%) physicians expected patients to choose no screening more often. For all groups the most important attribute was sensitivity, but physicians' perception of patients' preferences are significantly different from actual preferences. Other key attributes are those related to test performance or the testing process. Fecal DNA, colonoscopy, and virtual colonoscopy were the most preferred tests by all groups, but respondents were willing-to-pay more than physicians predicted.Physicians' perception of patients' preferences are quite different from those of the general population. However, among general population and physicians, Canadian and US preferences were similar.

Responses of inattentive or inconsistent subjects in stated-choice (SC) surveys can lead to imprecise or biased estimates. Several SC studies have investigated inconsistency and most of these studies dropped subjects who were inconsistent. However, none of these studies reported who is more likely to fail consistency tests. We investigated the effect of the personal characteristics and task complexity on preference inconsistency in eight different SC surveys. We found that white, higher-income and better-educated female subjects were less likely to fail consistency tests. Understanding the characteristics of subjects who are inattentive to the choice task may help in designing and pre-testing instruments that work effectively for a wider range of subjects. Copyright © 2009 John Wiley & Sons, Ltd.

In conjoint analysis (CA) studies, choosing between scenarios with multiple health attributes may be demanding for respondents. This study examined whether simplifying the choice task in CA designs, by using a design with more overlap of attribute levels, provides advantages over standard minimal-overlap methods. Two experimental conditions, minimal and increased-overlap discrete choice CA designs, were administered to 353 respondents as part of a larger HIV testing preference survey. In the minimal-overlap survey, all six attribute levels were allowed to vary. In the increased-overlap survey, an average of two attribute levels were the same between each set of scenarios. We hypothesized that the increased-overlap design would reduce cognitive burden, while minimally impacting statistical efficiency. We did not find any significant improvement in consistency, willingness to trade, perceived difficulty, fatigue, or efficiency, although several results were in the expected direction. However, evidence suggested that there were differences in stated preferences. The results increase our understanding of how respondents answer CA questions and how to improve future surveys.