PhD: Assessment of the external validity of discrete choice experiments: an application in pharmacy

[Back to PhD Projects]

The discrete choice experiment (DCE) technique has been applied extensively in the valuation of healthcare benefits to capture preferences. A key methodological question is if external validity i.e. the extent to which respondents’ choices made in a hypothetical DCE context, truly reflect their actual preferences. This thesis explored the external validity of DCEs within a pharmacy context. The thesis compared what respondents said they would do in a DCE survey with what they actually did when presented with the same scenario in real life. The thesis also explored the roles of uncertainty and attitudes in explaining discrepancies and uised qualitative research to provide insight.

The DCE correctly predicted 42.1% of participants’ actual choices. Calibration of the DCE with certainty questions and incorporation of the TPB into DCE improved DCE-prediction. Reasons for discrepancies in stated choice and actual behaviour included differences in decision-making processes in DCE and real life, attitudinal and other contextual factors (e.g. timing, location).

Outcome and Translation

Calibration methods should be considered to improve external validity. The development of DCEs, and the modelling of choice responses, should mimic as closely as possible the decision-making process individuals face in reality. This thesis extends the limited pool of empirical studies assessing external validity of DCEs.

PhD student: Gin Nie Chua

Supervisors: Mandy Ryan (HERU); T Porteous (HSRU, University of Aberdeen) and C Bond (Academic Primary Care, University of Aberdeen)


Chua, G.N. (2017) 'Using a discrete choice experiment to value a community pharmacy service: how valid are the findings?' PhD Thesis, HERU, University of Aberdeen.


Chua, G. N., Ryan, M., Bond, C. and Porteous, T. (2015) 'External validity of discrete choice experiment: early findings from a field experiment', 2nd European Health Economics Association (EuHEA) PhD Student - Supervisor Conference, Paris-Dauphine University, Paris, France, 2-4 September 2015.

Chua, G.N., Ryan, M., Bond, C. and Porteous, T. (2016) 'External validity of discrete choice experiments: findings from a field experiment', Health Economists' Study Group (HESG) Meeting, University of Manchester, Manchester, England, 6-8 January 2016.

Chua, G.N., Ryan, M. and Bond, C. (2016) 'Do respondents do as they say? Investigating the external validity of discrete choice experiments', International Academy of Health Preference Research (IAHPR) Meeting, Nord Event Panoramadeck, Hamburg, Germany, 13 July 2016.

Chua, G.N., Bond, C. and Ryan, M. (2016) 'Do respondents do as they say? A mixed method investigation of the external validity of discrete choice experiment', European Health Economics Association Conference, 'Know the Ropes - Balancing Costs and Quality in Health Care', Universität Hamburg, Germany 13-16 July 2016.

Chua, G.N., Ryan, M., Porteous, T. and Bond, C. (2016) 'Empirical testing of external validity of discrete choice experiment (DCE): an application in pharmacy', International Social Pharmacy Workshop 2016, University of Aberdeen, Aberdeen, 19-22 July 2016.

Ryan, M., Chua, G.N., Bond, C. and Porteous, T. (2018) 'External validity of choice experiments: a field experiment in pharmacy', 12th European Conference on Health Economics (EuHEA), Maastricht, The Netherlands, 11-14 July 2018.