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Background: To be able to make valid inferences on stated preference data from a Discrete Choice Experiment (DCE) it is essential that researchers know if participants were actively involved, understood and interpreted the provided information correctly and whether they used complex decision strategies to make their choices and thereby acted in accordance with the continuity axiom.Methods: During structured interviews, we explored how 70 participants evaluated and completed four discrete choice tasks aloud. Hereafter, additional questions were asked to further explore if participants understood the information that was provided to them and whether they used complex decision strategies (continuity axiom) when making their choices. Two existing DCE questionnaires on rotavirus vaccination and prostate cancer-screening served as case studies.Results: A large proportion of the participants was not able to repeat the exact definition of the risk attributes as explained to them in the introduction of the questionnaire. The majority of the participants preferred more optimal over less optimal risk attribute levels. Most participants (66%) mentioned three or more attributes when motivating their decisions, thereby acting in accordance with the continuity axiom. However, 16 out of 70 participants continuously mentioned less than three attributes when motivating their decision. Lower educated and less literate participants tended to mention less than three attributes when motivating their decision and used trading off between attributes less often as a decision-making strategy.Conclusion: The majority of the participants seemed to have understood the provided information about the choice tasks, the attributes, and the levels. They used complex decision strategies (continuity axiom) and are therefore capable to adequately complete a DCE. However, based on the participants' age, educational level and health literacy additional, actions should be undertaken to ensure that participants understand the choice tasks and complete the DCE as presumed. [ABSTRACT FROM AUTHOR]

Objective: To test whether presenting attribute levels in words or graphics generates different results with respect to attribute level interpretation, relative importance and participation probabilities.Methods: Parents of 959 newborns completed a DCE questionnaire that contained two versions of the same nine choice tasks in which the attribute levels were presented in words or graphics. Five attributes related to the decision of parents to vaccinate their newborn against rotavirus were included. Mixed-logit models were conducted to estimate the relative importance of the attribute levels.Results: Respondents who started with the choice tasks in words produced the most consistent answer patterns. All respondents significantly preferred words to graphics. Part-worth utilities and the relative importance of the attribute levels differed based on the words and graphics data, resulting in different probabilities to participate in vaccination.Conclusions: Words were preferred over graphics, resulted in higher choice consistency, and showed more valid attribute level estimates. Graphics did not improve respondents' understanding of the attribute levels.Practice Implications: Future research on the use of either words or graphics is recommended in order to establish guidelines on how to develop a valid presentation method for attribute levels in the choice tasks of a DCE. [ABSTRACT FROM AUTHOR]

Background: Both out-of-pocket costs and financial rewards can be used to influence health related behavior. However, it is unclear which of these two has a larger effect on health related behavior. The aim of this study was to explore the possible difference in effect size between out-of-pocket costs and financial rewards on the willingness of diabetes mellitus type 2 (DM2) patients to participate in a lifestyle program. Methods: A discrete choice experiment (DCE) questionnaire was sent to 767 DM2 patients in a geographically defined area (De Leidsche Rijn, Utrecht) in The Netherlands and completed by 206 of them. The questionnaire comprised of 18 choice tasks of which 9 contained a financial reward for lifestyle program completion, while the other 9 included out-of-pocket costs for program participation. In a second version of the questionnaire, the order of out-of-pocket cost and financial reward choice tasks was counterbalanced to reduce bias with respect to the position (first or second) of the two types of choice tasks. Panel-mixed-multinomial-logit models were used for data analysis. Results: Increasing out-of-pocket costs were associated with a decreasing willingness to participate in a lifestyle program and, contrary to our expectations, increasing financial rewards were also associated with a decreasing willingness to participate in a lifestyle program. In addition, this willingness to participate changed to the same extent for both increasing out-of-pocket costs and increasing financial rewards. Conclusions: As expected, increasing out-of-pocket costs may prevent people from deciding to participate in a lifestyle program. However, offering a financial reward to persuade people to participate in a lifestyle program, may result in decreasing willingness to participate in a lifestyle program as well. [ABSTRACT FROM AUTHOR]

Background: Preventive measures are essential to limit the spread of new viruses; their uptake is key to their success. However, the vaccination uptake in pandemic outbreaks is often low. We aim to elicit how disease and vaccination characteristics determine preferences of the general public for new pandemic vaccinations. Methods: In an internet-based discrete choice experiment (DCE) a representative sample of 536 participants (49% participation rate) from the Dutch population was asked for their preference for vaccination programs in hypothetical communicable disease outbreaks. We used scenarios based on two disease characteristics (susceptibility to and severity of the disease) and five vaccination program characteristics (effectiveness, safety, advice regarding vaccination, media attention, and out-of-pocket costs). The DCE design was based on a literature review, expert interviews and focus group discussions. A panel latent class logit model was used to estimate which trade-offs individuals were willing to make. Results: All above mentioned characteristics proved to influence respondents’ preferences for vaccination. Preference heterogeneity was substantial. Females who stated that they were never in favor of vaccination made different trade-offs than males who stated that they were (possibly) willing to get vaccinated. As expected, respondents preferred and were willing to pay more for more effective vaccines, especially if the outbreak was more serious (€6–€39 for a 10% more effective vaccine). Changes in effectiveness, out-of-pocket costs and in the body that advises the vaccine all substantially influenced the predicted uptake. Conclusions: We conclude that various disease and vaccination program characteristics influence respondents’ preferences for pandemic vaccination programs. Agencies responsible for preventive measures during pandemics can use the knowledge that out-of-pocket costs and the way advice is given affect vaccination uptake to improve their plans for future pandemic outbreaks. The preference heterogeneity shows that information regarding vaccination needs to be targeted differently depending on gender and willingness to get vaccinated. [ABSTRACT FROM AUTHOR]

Objective: To test how attribute framing in a discrete choice experiment (DCE) affects respondents' decision-making behavior and their preferences.Methods: Two versions of a DCE questionnaire containing nine choice tasks were distributed among a representative sample of the Dutch population aged 55 to 65 years. The DCE consisted of four attributes related to the decision regarding participation in genetic screening for colorectal cancer (CRC). The risk attribute included was framed positively as the probability of surviving CRC and negatively as the probability of dying from CRC. Panel mixed-logit models were used to estimate the relative importance of the attributes. The data of the positively and negatively framed DCE were compared on the basis of direct attribute ranking, dominant decision-making behavior, preferences, and importance scores.Results: The majority (56%) of the respondents ranked survival as the most important attribute in the positively framed DCE, whereas only a minority (8%) of the respondents ranked mortality as the most important attribute in the negatively framed DCE. Respondents made dominant choices based on survival significantly more often than based on mortality. The framing of the risk attribute significantly influenced all attribute-level estimates and resulted in different preference structures among respondents in the positively and negatively framed data set.Conclusions: Risk framing affects how respondents value the presented risk. Positive risk framing led to increased dominant decision-making behavior, whereas negative risk framing led to risk-seeking behavior. Attribute framing should have a prominent part in the expert and focus group interviews, and different types of framing should be used in the pilot version of DCEs as well as in actual DCEs to estimate the magnitude of the effect of choosing different types of framing. [ABSTRACT FROM AUTHOR]

Objectives: Our study investigates the extent to which uptake of a COVID-19 digital contact-tracing (DCT) app among the Dutch population is affected by its configurations, its societal effects, and government policies toward such an app.Methods: We performed a discrete choice experiment among Dutch adults including 7 attributes, that is, who gets a notification, waiting time for testing, possibility for shops to refuse customers who have not installed the app, stopping condition for contact tracing, number of people unjustifiably quarantined, number of deaths prevented, and number of households with financial problems prevented. The data were analyzed by means of panel mixed logit models.Results: The prevention of deaths and financial problems of households had a very strong influence on the uptake of the app. Predicted app uptake rates ranged from 24% to 78% for the worst and best possible app for these societal effects. We found a strong positive relationship between people's trust in government and people's propensity to install the DCT app.Conclusions: The uptake levels we find are much more volatile than the uptake levels predicted in comparable studies that did not include societal effects in their discrete choice experiments. Our finding that the societal effects are a major factor in the uptake of the DCT app results in a chicken-or-the-egg causality dilemma. That is, the societal effects of the app are severely influenced by the uptake of the app, but the uptake of the app is severely influenced by its societal effects. [ABSTRACT FROM AUTHOR]