External Validity of DCE-Version 1
Research type
Research Study
Full title
External Validity of Discrete Choice Experiment (DCE): A Field Experiment
IRAS ID
162718
Contact name
Mandy Ryan
Contact email
Clinicaltrials.gov Identifier
RG10519-10, Research Grant Reference Number
Duration of Study in the UK
0 years, 11 months, 27 days
Research summary
The discrete choice experiment (DCE) is a questionnaire-based technique which has been applied extensively to capture patients’ preferences for healthcare. The technique involves presenting respondents with hypothetical alternatives of a product and asking them to choose their preferred alternative in each choice set. Each alternative in the choice sets is differentiated by systematically varying the levels of attributes that define the product. The most prevailing methodological concern surrounding DCE is the issue of external validity i.e. the extent to which respondents’ choices, made in a hypothetical DCE context, truly reflect their actual preferences. The disparity between a respondent’s stated preference and actual behaviour is known as hypothetical bias (HB). The presence of HB threatens the external validity of valuation results and may lead to the under- or over-estimation of benefits. In this study, external validity of DCE will be investigated by comparing what respondents said they would do in a DCE survey, with what they actually do when presented with the same scenario in real life. The empirical study will be conducted within the context of community pharmacy service by applying a DCE to value pharmacist-led health screening services. In Phase I, pharmacy users will be asked to indicate their preference for the screening services in a DCE. Subsequently, in Phase II, they will be contacted and offered a real opportunity to purchase the screening service. The ‘real’ offer will be randomly picked from the pool of choice sets presented in the hypothetical DCE. Respondents’ choice behaviour under hypothetical and actual conditions will be compared; where there is a discrepancy, respondents will be interviewed to explore the potential factors contributing to HB. This study provides the most stringent form of validity testing for DCE and extends the limited pool of empirical studies assessing external validity of DCE.
REC name
North of Scotland Research Ethics Committee 2
REC reference
15/NS/0003
Date of REC Opinion
26 Jan 2015
REC opinion
Further Information Favourable Opinion