Abstract
Discrete choice experiments (DCEs) commonly include a monetary attribute. This enables willingness to pay (WTP), a monetary measure of benefit, to be estimated for non-monetary attributes. There has been concern that the inclusion of a cost attribute challenges the credibility of the experiment when valuing publicly funded healthcare systems. However, very little research has explored this issue. Using a UK sample, we allocated participants across two versions of a DCE: one including a cost attribute and the other excluding a cost attribute. The DCE was identical in all other respects. We find no significant difference in response time across the two surveys, monotonicity was higher for the COST DCE and cost
was stated as the most commonly ignored attribute in the COST DCE. Whilst the inclusion of a cost attribute did not alter the structure of preferences, it resulted in a lower level of choice consistency. Using an unrestricted latent class model, we find evidence of a credibility effect: respondents with experience of paying for health services and who perceive the choices as realistic are less likely to ignore cost. Further, respondents with a higher response time are less likely to be cost minimisers. Results are robust across different model specifications and
choice formats. DCE practitioners should give due consideration to cost credibility when including a cost attribute, ensuring participants engage with the cost attribute. Ways to do this are suggested, including careful motivation of the cost attribute, consideration to the appropriate payment vehicle and careful consideration to the cost attribute when developing and piloting the survey. Failure to do this will result in an invalid willingness to pay estimates and thus policy recommendations.
was stated as the most commonly ignored attribute in the COST DCE. Whilst the inclusion of a cost attribute did not alter the structure of preferences, it resulted in a lower level of choice consistency. Using an unrestricted latent class model, we find evidence of a credibility effect: respondents with experience of paying for health services and who perceive the choices as realistic are less likely to ignore cost. Further, respondents with a higher response time are less likely to be cost minimisers. Results are robust across different model specifications and
choice formats. DCE practitioners should give due consideration to cost credibility when including a cost attribute, ensuring participants engage with the cost attribute. Ways to do this are suggested, including careful motivation of the cost attribute, consideration to the appropriate payment vehicle and careful consideration to the cost attribute when developing and piloting the survey. Failure to do this will result in an invalid willingness to pay estimates and thus policy recommendations.
| Original language | English |
|---|---|
| Article number | 113822 |
| Number of pages | 11 |
| Journal | Social Science and Medicine |
| Volume | 276 |
| Early online date | 9 Mar 2021 |
| DOIs | |
| Publication status | Published - 1 May 2021 |
Bibliographical note
AcknowledgmentsWe thank all participants who took part in the study and three anonymous reviewers for their comments on the paper. The design of the discrete choice experiment on which this paper draws was shaped by a team that included, alongside two of the authors, Professor Chris Burton, Professor Vikki Entwistle, Professor Christine Bond, Dr Terry Porteous and Dr Alison Elliott.
Funding sources
The original DCE study was funded by the Health Foundation. This work has been funded by the University of Aberdeen and the Chief Scientist Office of the Scottish Government Health and Social Care Directorates. These sponsors were not involved in the study design, data analysis and writing of the article. The information and views set out in the article are those of the authors.
Keywords
- Multi-attribute choices
- Cost attribute
- Cost information processing
- Discrete choice experiment
- Publicly funded healthcare