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Introducing FACE, an instrument for assessing the face validity of choice experiments

Journal article (2026) - Annamarie de Ruijter, Job van Exel, Niek Mouter
Face validity indicates to what extent participants are engaged in making choices; and understand and interpret the presented information as intended by its designer. It is an important but often overlooked aspect of the overall validity of choice experiments and no comprehensive instruments for assessing it are available. Improving its design potentially improves the quality of participants’ responses and the study itself, which increases the relevance and usability for policy and practice. In this study we developed and tested an instrument to assess the FAce validity of Choice Experiments (FACE) in a uniform, systematic manner. The instrument is based on 9 components identified in the literature: clarity, completeness, decision certainty, familiarity, feasibility, legibility, relevance, sensitivity, and transparency. FACE covers these components in 13 statements with 5-point Likert scales. 1 020 participants completed the instrument following a discrete choice experiment on COVID-19 pandemic preparedness measures in the Netherlands. This first application of FACE showed that the face validity of a choice experiment was determined by whether participants considered its study design to be relevant, reliable and feasible. Moreover, we found that relevance and reliability were most strongly related to characteristics of the survey design, while feasibility was most strongly related to participants’ socio-demographic characteristics. Face validity was rated high(er) by participants who were younger, male, lower educated, vaccinated against COVID-19 and sufficiently engaged in the experiment. FACE should be regarded as a first-version instrument that can be refined and further validated. We provide recommendations on how to improve FACE in future research. ...

A constrained portfolio choice experiment” [J. Econ. Ageing 32 (2025) 100599]

Journal article (2026) - Sander Boxebeld, Niek Mouter, Job van Exel
The authors regret an unfortunate coding error in the optimal portfolio analysis presented in Table 3 of the published paper. This was discovered while performing new analyses on the data used in this study for another study. In the optimal portfolio analysis, the estimates of the multiple discrete-continuous extreme value (MDCEV) choice model were used to calculate the expected utility of each feasible portfolio (i.e., every possible combination of policy alternatives given the budget constraint, with attribute levels averaged over the sample). The expected utility was calculated correctly, but when preparing Table 3 for the paper, the portfolios were ranked incorrectly (i.e., by portfolio costs instead of by their expected utility). As a result, the top ten portfolios presented in Table 3 in the paper were not in fact the top ten portfolios in terms of expected utility, but in terms of implied additional expenditure on long-term care. In this corrigendum, we present the correct Table 3 and discuss these findings. The authors wish to emphasize that all the other analyses and results, i.e., the descriptive results (Figures 2, 3, S1 – S3, S8 – S14), the MDCEV estimates (Tables 2, S3, and S5), and the Latent Class Cluster Analysis (Tables 4, 5, and S2 and Figures S4 – S7) stay the same. Moreover, the abstract and highlights, and thereby the main message of the paper, remain unchanged. After ranking the portfolios by their expected utility, as originally intended, Table 3 reads as follows: [Table presented] The correct top ten portfolios indicate a stronger preference for the institutional and home-based formal care policy alternatives (i.e., increasing capacity of nursing homes, nursing care and social care at home, and introducing care homes), relative to those previously presented. At the same time, they indicate a lower preference for providing respite care to informal caregivers and introducing compulsory social service for young adults. Also, increasing the use of supportive care technologies is less preferred, but remains included in most of the top-ranked portfolios. This implies that portfolios involving a moderate increase in formal care options were generally preferred. The results reinforce the paper's conclusion that respondents seemed to prefer distributing public resources towards multiple policy alternatives over investing substantially in one or two particular policy alternatives. Finally, while the ten highest-ranked portfolios do not exhaust the budget constraint entirely, like in Table 3 of the paper, most portfolios still imply an expenditure increase close to exhausting the budget constraint. Based on the above, the subsection ‘Optimal portfolio composition’ of the Results section in the paper should be as follows: “Table 3 shows the ten portfolios with the highest expected utility. For example, portfolio 10 includes an increase in the capacity of nursing homes and nursing care at home by 10,000 places each, the introduction of care homes with 20,000 places (i.e., two times 10,000 places), an increase in the capacity of social care at home by 10,000 places, and the provision of respite care to informal caregivers for a maximum of three months, while increase in use of supportive care technologies and compulsory social service for young adults are not selected. Several patterns can be observed from the top ten portfolios. For example, each of these portfolios included at least one of the policy alternatives regarding nursing care and at least one regarding social care. Besides, all portfolios contained five or six of the seven policy alternatives. Additionally, both institutional care alternatives and both home-based care alternatives were included in all of the ten highest ranked portfolios, with the increased use of supportive care technologies also included at least once in seven out of the ten highest-ranked portfolios. All ten highest-ranked portfolios resulted in substantial expenditure increases, with eight of the ten portfolios nearly exhausting the resource constraint (i.e., > €90 euros per adult per month).” The sentences related to this part of the analysis in the Conclusion and Discussion section of the paper should be as follows: “In the optimal portfolios, increased capacity of institutional and home-based care and use of supportive care technologies were often included.” “Most of the highest-ranked portfolios nearly exhausted the budget constraint.” “The policy alternatives regarding the increased capacity of institutional and home-based care and use of supportive care technologies are particularly encouraged, conditional on the policies’ effectiveness and efficiency in practice. While various forms of institutional and home-based care are more commonly adopted and arguably less challenging to implement, the use of supportive care technologies in long-term care remains relatively limited.” Finally, the optimal portfolio composition in the sensitivity analysis also changes. It is similar to what is presented in the corrected Table 3 above, but with portfolios 6 and 7 and portfolios 8 and 9, respectively, reversed. The authors would like to apologise for any inconvenience caused. ...

Introducing Face, an Instrument for Assessing the Face Validity of Choice Experiments

Preprint (2025) - A.M. de Ruijter, Job van Exel, N. Mouter
Face validity indicates to what extent participants are engaged in making choices; and understand and interpret the information presented to them in the study as intended by its designer. It is an important but often overlooked aspect of the overall validity of choice experiments and no comprehensive instruments for assessing it are available. Improving the design of choice experiments potentially improves the quality of participants’ responses, which increases the relevance and usability for policy and practice. In this study we developed and tested an instrument to assess the FAce validity of Choice Experiments (FACE) in a uniform, systematic manner. The instrument is based on nine components that are used to define face validity identified from literature: acceptance, clarity, completeness, familiarity, feasibility, legibility, relevance, sensitivity, and transparency. FACE covers these components in 14 questions with 5-point Likert scales on which participants can indicate their level of agreement. 1,020 participants completed the instrument following a discrete choice experiment on COVID-19 pandemic preparedness measures in the Netherlands. This first application of FACE showed that the face validity of a choice experiment was determined by whether participants considered its study design to be relevant, reliable and feasible. Moreover, we found that relevance and reliability were most strongly related to characteristics of the survey design, while feasibility was most strongly related to participants’ socio-demographic characteristics. Face validity was assessed high(er) by participants who were younger, male, lower educated, vaccinated against COVID-19, supportive of policy responses to a pandemic situation and sufficiently engaged in the experiment. ...
Journal article (2025) - Karen Trujillo Jara, Jose Ignacio Hernandez, Niek Mouter, Werner Brouwer, Job van Exel
Background: The outbreak of COVID-19 was followed by an unprecedented package of measures to protect public health. Over 150 countries mandated school closures to reduce the risk of transmission. Decisions on whether to close schools involve trade-offs between important effects on public health, learning outcomes, well-being of children, productivity of parents. Objectives: Investigate Peruvian citizens’ preferences for schools opening during a public-health crisis such as the COVID-19 pandemic in two scenarios: (i) when the threat from COVID-19 is low and schools are open; and, (ii) when the threat from COVID-19 is high and schools are closed. Methods: We conducted a Participatory Value Evaluation (PVE) from 22 September to 17 October 2022, on which 2007 respondents assessed which policy measures to implement in the two scenarios. (i) In Scenario 1 “Schools are open”, children go to school, teachers and parents go to their jobs, but children still experience learning deficits from previous school closures. (ii) In Scenario 2 “Schools are closed”, children cannot go to school and do not receive any formal teaching, leading to learning losses; many teachers must change careers; and, many parents have to stay at home to take care of their children and lose income. Respondents were shown a range of policy measures in each of the scenarios and received information about the effects of each measure on public health, children's well-being and learning loss. Results: We found that most respondents in Scenario 1 preferred mandatory vaccination for teachers and quarantine measures. In Scenario 2 we found that most respondents were positive towards reopening school policies. In both Scenarios respondents prioritized mandatory vaccination and quarantine measures over other mitigation measures. In Scenario 2, most respondents from the Highland region selected opening schools with 100% on-location teaching while hybrid teaching was mostly selected in the Coast region. Most respondents (82%) evaluated PVE as a good method to involve citizens in policy decision-making. Conclusions: Policies that focus on prevention (e.g. mandatory vaccination for teachers and quarantine measures) can count on substantial support in a scenario when schools are open. The strong preference for opening schools with a noticeable difference in the way classes are provided (e.g. teaching on location most preferred by respondents from the Highlands and hybrid teaching by respondents from the Coast) show the importance of introducing differentiated strategies among regions. ...
Journal article (2025) - Sander Boxebeld, Niek Mouter, Job van Exel
Many countries face rapidly ageing populations, resulting in a rising demand for long-term care (LTC) for older people and an increased pressure on LTC systems. In responding to this development, governments face challenging trade-offs between different policy measures and their effects. To inform allocation decisions, this study elicited citizens’ policy preferences for LTC for older people in the Netherlands in 2040. We conducted a constrained portfolio choice experiment, in which 997 respondents composed a portfolio of their preferred policies, subject to a budget constraint, while being presented with the expected effects of their choices. Choices were analysed using a Multiple Discrete Continuous Extreme Value (MDCEV) choice model and a Latent Class Cluster Analysis (LCCA). The results suggest a preference for distributing resources towards multiple policies, including both nursing and social care, over investing heavily in one or two particularly. Also, most respondents chose portfolios constituting a substantial public expenditure increase, suggesting a widespread willingness to accept a tax increase to allow for this. Preferences were particularly heterogeneous with respect to expenditure levels and the adoption of supportive care technologies and compulsory social service for young adults. Policymakers may use these results to support the selection of a portfolio of LTC policies that aligns with public preferences. ...

A discrete choice experiment in three European countries

Journal article (2025) - Sander Boxebeld, Niek Mouter, Job van Exel
Objective: In many countries, the incidence of skin cancer is growing rapidly, resulting in a substantive health and economic burden. While the wide range of available skin cancer prevention policies may have large individual and societal benefits, many countries still lack a policy strategy, and little is known about public preferences for collective prevention policy measures. We elicited these preferences using a discrete choice experiment (DCE) in Austria, the Netherlands, and Spain to inform policy action. Methods: Respondents were asked to choose twelve times between two packages of different prevention policies. Each package was described by its estimated effectiveness and costs. Before and after the DCE, respondents were asked for their support for any policy action. We quota-sampled adult citizens in each of the countries from an online panel (N = 2,442). The choice data were analyzed using multinomial logit (MNL) and mixed multinomial logit (MMNL) models. Results: Almost all attributes significantly influenced respondents’ choices, with the tax attribute being most influential in each country. Among the six policy measures, information campaigns and a price reduction of sunscreen were the most preferred policy measures, and the prohibition of solar bed sales and solaria the least preferred. Preference structures were largely consistent across the countries. Finally, most respondents supported policy action, particularly after the DCE. Conclusions: Citizens in the three countries recommended their governments to take policy action against the increasing incidence of skin cancer. The results provide policymakers with directions for publicly supported policy action, which should be complemented with additional information on preference heterogeneity, citizens' argumentation, and policies’ relative (cost-)effectiveness. The suggestion that preferences for policy action adapted over the course of completing the DCE survey should be further examined. ...
Journal article (2024) - Sander Boxebeld, Tom Geijsen, Charlotte Tuit, Job van Exel, Amr Makady, Laurence Maes, Michel van Agthoven, Niek Mouter
Objective: Increasing healthcare expenditures require governments to make difficult prioritization decisions. Considering public preferences can help raise citizens’ support. Previous research has predominantly elicited preferences for the allocation of public resources towards specific treatments or patient groups and principles for resource allocation. This study contributes by examining public preferences for budget allocation over various healthcare purposes in the Netherlands. Methods: We conducted a Participatory Value Evaluation (PVE) choice experiment in which 1408 respondents were asked to allocate a hypothetical budget over eight healthcare purposes: general practice and other easily accessible healthcare, hospital care, elderly care, disability care, mental healthcare, preventive care by encouragement, preventive care by discouragement, and new and better medicines. A default expenditure was set for each healthcare purpose, based on current expenditures. Respondents could adjust these default expenditures using sliders and were presented with the implications of their adjustments on health and well-being outcomes, the economy, and the healthcare premium. As a constraint, the maximum increase in the mandatory healthcare premium for adult citizens was €600 per year. The data were analysed using descriptive statistics and a Latent Class Cluster Analysis (LCCA). Results: On average, respondents preferred to increase total expenditures on all healthcare purposes, but especially on elderly care, new and better medicines, and mental healthcare. Three preference clusters were identified. The largest cluster preferred modest increases in expenditures, the second a much higher increase of expenditures, and the smallest favouring a substantial reduction of the healthcare premium by decreasing the expenditure on all healthcare purposes. The analyses also demonstrated substantial preference heterogeneity between clusters for budget allocation over different healthcare purposes. Conclusions: The results of this choice experiment show that most citizens in the Netherlands support increasing healthcare expenditures. However, substantial heterogeneity was identified in preferences for healthcare purposes to prioritize. Considering these preferences may increase public support for prioritization decisions. ...

A New Preference-Elicitation Method for Decision Making in Healthcare

Journal article (2023) - Sander Boxebeld, Niek Mouter, Job van Exel
Participatory value evaluation (PVE) has recently been introduced in the field of health as a new method to elicit stated preferences for public policies. PVE is a method in which respondents in a choice experiment are presented with various policy options and their attributes, and are asked to compose their portfolio of preference given a public-resource constraint. This paper aims to illustrate PVE’s potential for informing healthcare decision making and to position it relative to established preference-elicitation methods. We first describe PVE and its theoretical background. Next, by means of a narrative review of the eight existing PVE applications within and outside the health domain, we illustrate the different implementations of the main features of the method. We then compare PVE to several established preference-elicitation methods in terms of the structure and nature of the choice tasks presented to respondents. The portfolio-based choice task in a PVE requires respondents to consider a set of policy alternatives in relation to each other and to make trade-offs subject to one or more constraints, which more closely resembles decision making by policymakers. When using a flexible budget constraint, respondents can trade-off their private income with public expenditures. Relative to other methods, a PVE may be cognitively more demanding and is less efficient; however, it seems a promising complementary method for the preference-based assessment of health policies. Further research into the feasibility and validity of the method is required before researchers and policymakers can fully appreciate the advantages and disadvantages of the PVE as a preference-elicitation method. ...
Journal article (2023) - Aemiro Melkamu Daniel, Job van Exel, Caspar G. Chorus
Efficiently allocating scarce healthcare resources requires nuanced understanding of individual and collective interests as well as relative concerns, which may overlap or conflict. This paper is the first to empirically investigate whether and to what extent self-interest (SI), positional concerns (PC) and distributional considerations (DC) simultaneously explain individual decision making related to access to healthcare services. Our investigation is based on a stated choice experiment conducted in two countries with different healthcare systems, the United States (US) and the United Kingdom (UK). The choice experiment is on allocation of medical treatment waiting times for a hypothetical disease. We carry out the investigation under two different perspectives: (i) in a socially inclusive personal perspective decision makers were asked to choose between waiting time distributions for themselves and (ii) in a social perspective decision makers were asked to make similar choices for a close relative or friend of opposite gender. The results obtained by estimating a variety of advanced choice models indicate that DC, SI and PC, in this order of importance, are significant drivers of choice behaviour in our empirical context. These findings are consistent regardless of the choice perspective and the country where decision makers live. Comparing the results from different choice perspectives, we find that US respondents who chose for their close relative or friend attach significantly larger weight to their close relative’s or friend’s waiting times as well as to the overall distribution of waiting times than US respondents who chose for themselves. Looking at differences between countries, our results show that UK respondents who made choices for themselves placed significantly larger weight on SI and DC than US respondents, while US respondents, in turn, displayed relatively stronger but not significantly different positional concerns than UK respondents. In addition, we observe that UK respondents who chose for their close relative or friend put a larger weight on DC than their US counterparts. We conclude that the methodological (data collection and analysis) approach allows for disentangling the relative importance of the three motivations and discusses the potential implications of these findings for healthcare decision making. ...

A Discrete Choice Experiment in the Netherlands

Journal article (2023) - J. Veldwijk, J. van Exel, E. W. de Bekker-Grob, N. Mouter
Objective: Here we investigate public preferences for coronavirus disease 2019 (COVID-19) certificates in the Netherlands, and whether these preferences differ between subgroups in the population. Methods: A survey including a discrete choice experiment was administered to 1500 members of the adult population of the Netherlands. Each participant was asked to choose between hypothetical COVID-19 certificates that differed in seven attributes: the starting date, and whether the certificate allowed gathering with multiple people, shopping without appointment, visiting bars and restaurants, visiting cinemas and theatres, attending events, and practising indoor sports. Latent class models (LCMs) were used to determine the attribute relative importance and predicted acceptance rate of hypothetical certificates. Results: Three classes of preference patterns were identified in the LCM. One class a priori opposed a certificate (only two attributes influencing preferences), another class was relatively neutral and included all attributes in their decision making, and the final class was positive towards a certificate. Respondents aged > 65 years and those who plan to get vaccinated were more likely to belong to the latter two classes. Being allowed to shop without appointment and to visit bars and restaurants was most important to all respondents, increasing predicted acceptance rate by 12 percentage points. Conclusions: Preferences for introduction of a COVID-19 certificate are mixed. A certificate that allows for shopping without appointment and visiting bars and restaurants is likely to increase acceptance. The support of younger citizens and those who plan to get vaccinated seems most sensitive to the specific freedoms granted by a COVID-19 certificate. ...
Journal article (2022) - Niek Mouter, Annamarie de Ruijter, G. Ardine de Wit, Mattijs S. Lambooij, Maarten van Wijhe, Job van Exel, Roselinde Kessels
Background: Vaccination is generally considered the most direct way to restoring normal life after the outbreak of COVID-19, but the available COVID-19 vaccines are simultaneously embraced and dismissed. Mapping factors for vaccine hesitancy may help the roll-out of COVID-19 vaccines and provide valuable insights for future pandemics. Objectives: We investigate how characteristics of a COVID-19 vaccine affect the preferences of adult citizens in the Netherlands to take the vaccine directly, to refuse it outright, or to wait a few months and first look at the experiences of others. Methods: An online sample of 895 respondents participated between November 4th and November 10th, 2020 in a discrete choice experiment including the attributes: percentage of vaccinated individuals protected against COVID-19, month in which the vaccine would become available and the number of cases of mild and severe side effects. The data was analysed by means of panel mixed logit models. Results: Respondents found it important that a safe and effective COVID-19 vaccine becomes available as soon as possible. However, the majority did not want to be the first in line and would rather wait for the experiences of others. The predicted uptake of a vaccine with the optimal combination of attributes was 87%, of whom 55% preferred to take the vaccine after a waiting period. This latter group tends to be lower-educated. Older respondents gave more weight to vaccine effectiveness than younger respondents. Conclusions: The willingness to take a COVID-19 vaccine is high among adults in the Netherlands, but a considerable proportion prefers to delay their decision to vaccinate until experiences of others are known. Offering this wait-and-see group the opportunity to accept the invitation at a later moment may stimulate vaccination uptake. Our results further suggest that vaccination campaigns targeted at older citizens should focus on the effectiveness of the vaccine. ...

A Discrete Choice Experiment in The Netherlands

Journal article (2022) - Niek Mouter, Sander Boxebeld, Roselinde Kessels, Maarten van Wijhe, Ardine de Wit, Mattijs Lambooij, Job van Exel
Objectives: The COVID-19 pandemic forms an unprecedented public health, economic, and social crisis. Uptake of vaccination is critical for controlling the pandemic. Nevertheless, vaccination hesitancy is considerable, requiring policies to promote uptake. We investigate Dutch citizens’ preferences for policies that aim to promote vaccination through facilitating choice of vaccination, profiling it as the norm, making vaccination more attractive through rewards, or punishing people who reject vaccination. Methods: We conducted a discrete choice experiment in which 747 respondents were asked to choose between policies to promote vaccination uptake and their impacts on the number of deaths, people with permanent health problems, households with income loss, and a tax increase. Results: Respondents generally had a negative preference for policies that promote vaccination. They particularly disliked policies that punish those who reject the vaccine and were more favorable toward policies that reward vaccination, such as awarding additional rights to vaccinated individuals through vaccination passports. Respondents who reject vaccination were in general much more negative about the policy options than respondents who consider accepting the vaccine. Nevertheless, vaccination passports are supported by both respondents who accept the vaccine, those who reject vaccination, and those who are unsure about vaccination. Conclusions: This study provides concrete directions for governments attempting to increase the vaccination uptake in ways that are supported by the public. Our results could encourage policy makers to focus on policy options that make vaccination easier and reward people who take the vaccine, as especially the implementation of vaccination passports was supported. ...