Valuation Task and Context

Valuation Task and Context

The valuation task and contextual factors influence valuations elicited in stated preference surveys. Our research in this area focuses on the comparing elicited values across different valuation tasks and surveys, and comparing different types of preferences.

Current Projects

The effects of online deliberation on altruistic preferences and moral reasoning

We are investigating the effect of online deliberation on subjects participating in a Discrete Choice Experiment (DCE). We explore the existence of a preference shift towards more altruistic preference in relation to text-based online communication between participants. We are also investigating the effect of deliberation on the prevalence of self-interested moral reasoning and other-regarding moral reasoning. The combination of online deliberation and DCEs has the potential to broaden the evaluative space of DCEs and presents an exciting opportunity to collect qualitative data on the reasons for participant choices in DCEs.

Our research examines existing quantitative and qualitative data from a choice experiment asking participants about their preference towards donating money to different charities. The choice options differed in the kind of charity (health based vs. a broader social focus), the amount to be donated, and the donation amount that would be matched by the researcher.

The experiment consisted of 3 arms:

  • Arm 1 asked individual participants to commit to a real donation funded out of their compensation;
  • Arm 2 asked participants to make an individual choice for a real donation after discussing their options with another participant via online text-based communication; and
  • Arm 3 participants engaged in online communication to come to a unanimous decision for a real donation.

HERU researchers involved in this research project: Mandy Ryan and Ruben Sakowsky

External collaborators: Emmanouil Mentzakis (University of Southampton)

Reducing land degradation and carbon loss from Ethiopia's soil to strengthen livelihoods and resilience (RALENTIR)

Land and soil degradation is a major problem in Ethiopia as in many countries in Sub-Saharan Africa. Restoring degraded common lands through the establishment of "exclosure" areas where traditional community access is restricted is common in Ethiopia. Both degradation and measures to restore land are inherently unequally distributed in time and space. Hence, aspects of justice and equity need to be taken into account for soil restoration measures to be sustainable in the long run.

The project will develop and apply frameworks for the analysis of equity within the case study areas to design specific interventions. Through a range of participatory, communication, and survey methods the project will explore - the impact of the interventions on the participants in terms of their attitudes, changes in behaviour, livelihoods etc - the influence of process characteristics, power relationships and communication practices on people's responses to these interventions - what worked/what didn't, how it compared to expectations - the impact of the changing knowledge and experience of the interventions on wider attitudes and community preferences for local natural resource governance.

HERU researchers involved in this research project: Verity Watson

External collaborators: Phimister, E. (Business School, University of Aberdeen); Smith, J.U., Hallett, P. (Institute of Biological and Environmental Science, University of Aberdeen); Mekuria, W., Haile, A., Tekle, A. (Nile Basin & East Africa Office, International Water Management Institute); Ameda, T.T., Lemma Argaw, T. (Hawassa University); Byg, A. (James Hutton Institute); Edo., G. (Southern Agricultural Research Institute); Fischer, A. (Swedish University of Agricultural Science); Allan, J. (Health Psychology, University of Aberdeen) and Scott, T. (University of Melbourne).

Recently Completed Projects

Choice certainty and deliberative thinking in discrete choice experiments. A theoretical and empirical investigation

Stated preference research is criticised because respondents to hypothetical surveys may not engage with the task. Decision certainty has been used to measure task engagement. Researchers assume that respondents who make decisions about which they are certain have well-defined preferences and provide more reliable responses. In the case of DCE, we argue that the variability of response certainty is also important. We present a novel framework to identify thoughtful / deliberative respondents.

The framework combines respondents’ decision certainty with the variability in respondents’ decision certainty across a set of choice tasks. We test our framework empirically using data from two case studies. We find respondents with higher certainty variability seldom use decision heuristics, are more likely to have monotonic preferences, and have longer response times. We then incorporate mean decision certainty and variability into econometric models of choice to provide more precise estimates of individuals' preferences. We find that a re-weighting function that includes variability improves the precision of welfare estimates up to 69%.

Outcome and Translation

Respondents with higher certainty variability seldom use decision heuristics, are more likely to have monotonic preferences, and have longer response times. A re-weighting function that includes variability improves the precision of welfare estimates up to 69%.

HERU researchers involved in this research project: Verity Watson

External collaborators:  Reiger, D. (British Columbia Cancer Research Agency and University of British Columbia); Sicsic, J. (Paris Descartes University Institute of Technology)


Gatekeeping in intensive care: what factors influence professionals’ decision-making surrounding admission to the intensive care unit

Informed by a literature review and data from observation and interviews with ICU clinicians and outreach nurses, we designed a choice experiment. Senior intensive care doctors (consultants) and nurses were presented with pairs of patient profiles and asked to prioritize one of the patients in each task for admission to ICU.

For the consultants, patient’s age had the largest impact at admission followed by the views of their family, and severity of their main comorbidity. Physiologic measures indicating severity of illness had less impact than the gestalt assessment by the ICU registrar. We identified four distinct decision-making patterns, defined by the relative importance given to different factors. 

Outcome and Translation

ICU consultants vary in the importance they give to different factors in deciding who to prioritize for ICU admission. Transparency regarding which factors have been considered in the decision-making process could reduce variability and potential inequity for patients.

HERU researchers involved in this research project: Mandy Ryan and Nicolas Krucien

External collaborators: C. Bassford, F. Griffiths, G. Perkins, S. Quinton, K. Rees and A.M. Slowther (University of Warwick)


Health state valuation using discrete choice experiments and best-worst scaling: a comparison of methods

Health utility indices (HUIs) are widely used in economic evaluation. The best–worst scaling (BWS) method is used to value dimensions of HUIs. However, little is known about the properties of this method. We investigate the validity of the BWS method to develop HUI, comparing it to another ordinal valuation method, the discrete choice experiment (DCE).

Using a parametric approach we find a low level of concordance between the two methods, with evidence of preference reversals. BWS responses are subject to decision biases, with significant effects on individuals’ preferences. Non-parametric tests indicate BWS data has lower stability, monotonicity and continuity compared to DCE data, suggesting the BWS provides lower quality data.

Outcome and Translation

For both theoretical and technical reasons, practitioners should be cautious both about using the BWS method to measure health-related preferences, and about using HUI based on BWS data. Given existing evidence it seems that the DCE method is a better method, at least because its limitations (and measurement properties) have been extensively researched.

HERU researchers involved in this research project: Nicolas Krucien, Verity Watson and Mandy Ryan


Integrating monetary and non-monetary approaches to assessing shared, plural and cultural values of ecosystems

By improving our understanding of the differences between individual, shared, plural and cultural values, and how to assess them, this research will provide policy-makers with the evidence and tools necessary to give social impacts more robust consideration in future policy decisions.

The project includes three deliberative monetary- and non-monetary valuation case studies assessing the value of ecosystem services (the benefits of ecosystems to human well-being). These consider how social processes might shape shared values, and will test the merit of different monetary and non-monetary techniques for capturing these values. Although the project is largely framed around ecosystems and biodiversity, it will also review shared values around health and the project outcomes are expected to be valuable to all fields requiring social-economic valuation of non-marketed goods.

Outcome and Translation

Shared values are different from individual values and elicitation of shared values can have substantial advantages over conventional individual valuation. The ethical, moral and justice dimensions of many environmental issues necessitate approaches that allow for the elicitation of shared and plural values. However, there is widespread conflation and diversity of ways in which shared, plural, cultural and social values are used, but they are rarely conceptualised and often they are used interchangeably.

A mixed method approach is required to elicit the multiple dimensions of shared values. Deliberative and social learning processes can help people understand the values of others and can lead to increased sharing of values or greater acceptance of the decisions that emerge from such processes.

This research is a collaboration with the Aberdeen Centre for Environmental Sustainability (ACES) within the National Ecosystem Assessment Shared Values Working Group.

HERU researchers involved in this research project: Verity Watson and Mandy Ryan

External collaborators are: J Kenter (Aberdeen Centre for Environmental Sustainability, University of Aberdeen) and M Pinard (School of Biological Sciences, University of Aberdeen)


Investigation of the value placed on the National Clinical Assessment Service by referrers in the National Health Service

In 2008 around 800 performance concern cases were referred to the attention of the NHS National Clinical Assessment Service (NCAS) from all parts of the UK. These cases required NCAS support, which ranges from phone advice to major and multidimensional assessment with the possibility of suspending or excluding the healthcare professional. A ‘mixed methods’ approach was used to investigate NHS organisations’ preferences for the services provided by NCAS.

The study combined interviews, discussion groups and a discrete choice experiment (DCE). The discussion groups explored which aspects of the services provided by NCAS are important and why, and the discussion groups were used to identify drivers of preference heterogeneity for NCAS services.

The focus groups and discussion groups informed the DCE, which was administered during 2010. The final report was published in June 2010 by NCAS. This project informed NCAS about the value to NHS organisations of clinical performance support services.

Outcome and Translation

The results of this study can be used to assess the value for money of NCAS, and can inform future changes to the range of services which they provide.

HERU researchers involved in this research project: Verity Watson and Mandy Ryan

External collaborators: J Sussex (Office of Health Economics)


Re-thinking the different perspectives that can be used when eliciting preferences in health

The 2003 Health Economics paper ‘An inquiry into the different perspectives that can be used when eliciting preferences in health’ presents a conceptual framework of six perspectives along two dimensions: preferences (personal, social and socially inclusive personal) and context (ex ante and ex post).

We rethink this framework by asking four questions concerning: the patient, or the user of the treatment; the payer of the treatment; and the assessor of the value of treatment; and the timing of the illness and the nature of its risk.

These questions refine the preference and context dimensions, and leads to the identification of perspectives not classified by the original framework. We propose an extended framework with five preferences (personal, non-use, proxy, social and socially inclusive personal) and five contexts (one of which is ex post and four ex ante), resulting in 22 possible perspectives.

Outcome and Translation

We show that the DOMR framework is imprecise and incomplete in both the preference and context dimensions. Our extended five-by-five framework will facilitate comparisons across empirical studies with more clarity at the conceptual level. Our extended framework has better coverage to accommodate the expanded range of contexts in which preference elicitation is applied.

HERU researchers involved in this research project: Verity Watson

External collaborators: A Tsuchiya (ScHAAR, University of Sheffield)


Spending wisely: investigating survey mode effects in discrete choice experiment responses

We compared four survey modes: internet panel survey, mail survey, mail invitation to complete an internet survey and in-person interviews andcompared responses to a survey designed to elicit preferences of a healthcare ‘good’ likely to be relevant to all members of the population: the use of community pharmacies for managing minor illness. Preference data were collected using a DCE. For each mode, we considered: 

  1. How representative of the population were respondents to each mode?
  2. Did respondents’ preferences and willingness to pay vary across modes?
  3. Could statistical techniques be used to take account of differences in respondent characteristics?
  4. Did response validity vary across modes?

Outcome and Translation

The mail invitation to complete an internet survey was not taken forward to the main study after an extremely low response rate to the pilot. None of the modes were representative of the general population. Each mode differed from the general population in different ways. For example, while respondents to the mail survey were older, on average, than the general population, respondents to the internet panel surveys were younger. Respondents’ preferences and willingness to pay differed across modes. Response validity also differed across modes.

The results provide researchers with a characterisation and quantification of the advantages and disadvantages of each mode and thus allow them make an informed decision about which mode(s) to use in their research.

HERU researchers involved in this research project: Mandy Ryan and Verity Watson

External collaborators: T Porteous (Academic Primary Care, University of Aberdeen)


PhD: Investigating willingness to pay for low emission public transportation

In this thesis, we investigated how much bus users’ are willing to pay to reduce emissions that cause air pollution from buses using a Discrete Choice Experiment (DCE). We considered two different types of emissions separately: global emissions that cause climate change and local emissions that impact on health. The context of the study is an existing low emission bus (LEB) scheme – the Aberdeen Hydrogen Bus Project. The thesis addressed three research questions:

  1. Whether bus users value reduction in emissions from buses and determine if people distinguish between different types of emissions?

  2. If experience from regularly using a hydrogen bus has as an effect on the value users place in different characteristics of the bus service?

  3. Exploration of asymmetries in the preferences for attributes using a reference-dependent (pivoted) experimental design.  

This is the first study to investigate the effect of the introduction of a low emission public transport scheme on its users’ valuations using a DCE. The results provide us with insight to better inform how to implement LEB schemes.

Outcome and Translation:

Aberdeen bus users value buses that are cheaper, more frequent, more punctual and reduced emissions. Respondents seem to place a higher value in reducing local pollutant emissions than greenhouse gas emissions, thus suggesting they care more about emissions which have local consequences (i.e. poorer local air quality) than those that have global consequences (i.e. climate change). There was evidence of preference heterogeneity across the sample, specifically when splitting the sample based on the level of experience of using a hydrogen bus. Bus users with more experience using a hydrogen bus as their main service placed a higher value on reduced emissions and improved comfort inside the bus when compared to users with no or little experience using the hydrogen bus. Reduced emissions and increased comfort are the most salient differences between a hydrogen bus and a diesel bus, thus this was interpreted as experience of using the hydrogen buses having an effect in preferences. Finally, bus users’ preferences were consistent with prospect theory. Preferences for frequency, punctuality and fare exhibited loss aversion (loses loomed larger than gains), reference dependence and diminishing marginal utilities. This has policy implications, as the allocation of resources for a bus service should not assume linearity of preferences. For example, an improvement in frequency in one service will not make up for a similar deterioration in another service.

PhD Student: Luis Loría

Supervisors: Verity Watson (HERU); Kiso, T., Phimister, E. (Economics, UABS)


PhD: Our values or mine? A philosophical and empirical critique of deliberative and stated preference elicitation techniques in health economics

The thesis evaluates to what extent health economic stated preference methods and deliberative approaches towards health preference elicitation allow participants to express normative considerations that are related to the well-being of others, register preferences that take the social status of beneficiaries into account, and express normative evaluations that go beyond a consequentialist focus on outcomes. In addition, the thesis assesses to what degree participants are afforded the opportunity for peer interaction and peer discussion, evaluates the sensitivity of elicitation methods towards participants undergoing preference transformation, and assesses to what degree health economic preference elicitation methods are compatible with the concept of collective moral authorship.

For the assessment, the thesis combines a philosophical analysis of the theoretical paradigms of neoclassical health economics and deliberative democratic theory with an evaluation of how both approaches relate to the practice of health preference elicitation. To the latter end, the thesis presents the findings of a literature review of health-related stated preference studies and discusses the results of qualitative interviews with the participants of two deliberative Community Juries on the topic of disinvestment in breast cancer screening.

Outcome and Translation

The thesis argues for the increased utilization of deliberative methods in health economic preference research alongside preference elicitation methods. 

PhD Student: Ruben Sakowsky

Supervisors: Mandy Ryan (HERU) and V. Entwistle (Health Services Research Unit, University of Aberdeen)


PhD: Testing methods to value health outcomes in low income countries using contingent valuation and discrete choice experiment methods

This PhD contributed to the small body of literature on the application of CV and DCEs in low-income countries and in populations which have little or no formal education. Theoretical validity was examined by testing whether willingness to pay corresponded to theoretical expectations focussing on gender and willingness to pay, sensitivity to scope, starting point bias, and strategic bias in CV. The theoretical validity of the DCE method in populations with no formal education was also explored.

Outcome and Translation

Both CV and DCEs were found to be feasible and valid in populations with low levels of education when surveys were conducted using trained enumerators, administered using face-to-face interviews and using visual aids. However, iterative methods to elicit willingness to pay were prone to starting point bias and strategic bias.

PhD Student: Laura Ternent

Supervisors: Paul McNamee (HERU)