Dr Leonie Burgess

Street, D. & Burgess, L.B. 2007, The Construction of Optimal Stated Choice Experiments: Theory and Methods, 1, John Wiley and Sons, Hoboken, New Jersey.
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Street, D. & Burgess, L.B. 2012, 'Designs for choice experiments for the multinomial logit model' in Klaus Hinkelmann (ed), Design and Analysis of Experiments: Special Designs and Applications Volume 3, John Wiley & Sons, United States, pp. 331-378.
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People make choices all the time; some of these are minor, like deciding what clothes to wear to work today, but some are major and of interest to governments and businesses. Governments might be interested in modelling demand for health services in the future, for instance, or in assessing the likely impact on the electorate of a decision to allow mining or logging in national parks. Businesses want to predict the likely market for new goods and services. To get information about products or services that do not yet exist, an experimental approach is appropriate. Such experiments are called +stated preference+ or +stated choice+ experiments. This chapter provides an overview of the best way to design generic stated preference choice experiments, from a mathematical perspective. A more extensive discussion appears in Street and Burgess (2007).

Street, D., Burgess, L.B., Viney, R.C. & Louviere, J.J. 2008, 'Designing Discrete Choice Experiments for Health Care' in Ryan,M; Gerard, K; Amaya-Amaya, M. (eds), Using Discrete Choice Experiments to Value Health and Health Care, Springer, Dordrecht, The Netherlands, pp. 47-72.
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As noted in Chapter 1, the application of discrete choice experiments (DCEs) in health economics has seen an increase over the last few years.While the number of studies using DCEs is growing, there has been relatively limited consideration of experimental design theory and methods. Details of the development of the designed experiment are rarely discussed. Many studies have used small fractional factorial designs (FFDs), generated with commercial design software packages, e.g. orthogonal main effects plans (OMEPs), sometimes manipulated in ad hoc ways (e.g. randomly pairing up scenarios or taking one scenario from the design and combining it with every other scenario). Such approaches can result in designs with unknown statistical design properties, in particular with unknown correlations between parameter estimates.

Burgess, L.B., Street, D., Viney, R.C. & Louviere, J.J. 2006, 'Design of choice experiments in health economics' in Jones, A M (eds), The Elgar Companion to Health Economics, Edward Elgar, Cheltenham, UK, pp. 415-426.
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Louviere, J.J., Street, D. & Burgess, L.B. 2004, 'A 20+ years' retrospective on choice experiments' in Wind, Y; Green, P E (eds), Marketing Research and Modeling: Progress and Prospects, Kluwer Academic Publishers, Boston, pp. 201-214.
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Paul Green inspired many of us who work in conjoint analysis and related areas, such as stated preference discrete choice experiments, and all of us who undertake research in understanding and modelling preferences have benefited from his work. Knowing Paul Green, his impact and contributions will continue during his "returement". Our thanks to him for so many of the advances that we now often take for granted, but without which we would not be where we are today. In tribute to Paul Green, this paper provides a bried history of choice experiments, how the results of choice experiments relate to real market behaviour,. and progress that has been made int he design of choice experiments. We concludee by discussing several aspects of choice experimens, such as the interacctions of subjects with experiments, model complexity and the scientific understanding of choice behaviour compared with mere predictions of choices.

Lancsar, E., Louviere, J.J., Currie, G., Donaldson, C. & Burgess, L.B. 2013, 'Best Worst Discrete Choice Experiments in Health: Methods and an Application', Social Science & Medicine, vol. 76, pp. 74-82.
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A key objective of discrete choice experiments is to obtain sufficient quantity of high quality choice data to estimate choice models to be used to explore various policy/clinically relevant issues. This paper focuses on a relatively new form of choice experiment, `Best Worst Discrete Choice Experiments+ (BWDCEs) and their relevance to health research as a new way to meet such an objective. We explain what BWDCEs are, how and when to apply them and we present several analytical approaches to model the resulting data. We demonstrate this preference elicitation approach in an empirical application exploring preferences of 898 members of the general public in Edmonton and Calgary, Canada for treatment of cardiac arrest occurring in a public place and show the gains achieved compared to traditional analysis of first best data. We suggest that BWDCEs are a valuable way to investigate preferences in the health sector and discuss implications for task design, analysis and areas for future research.

Bush, S.A., Street, D. & Burgess, L.B. 2012, 'Optimal designs for stated choice experiments that incorporate position effects', Communications in Statistics - Theory and Methods, vol. 41, no. 10, pp. 1771-1795.
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Davidson and Beaver (1977) extended the Bradley-Terry model to incorporate the possible effect of position within a choice set on the choices made in paired comparisons experiments. We further extend the Davidson-Beaver result to choice sets of any size and show, under a mild restriction, that designs optimal for the multinomial logit model are still optimal. Designs balanced for carry-over effects of all orders can be used to construct designs with a diagonal information matrix for attribute effects. The theoretical results are derived assuming equal merits and we discuss the possible consequences of assuming unequal merits in an example.

Burgess, L.B., Street, D. & Wasi, N. 2011, 'Comparing designs for choice experiments: A case study', Journal of Statistical Theory and Practice, vol. 5, no. 1, pp. 25-46.
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This paper describes an empirical comparison of the performance of four designs for a discrete choice experiment. These designs were chosen to represent the range of construction techniques that are currently popular for choice experiments when no prior knowledge of the parameters is available. Each design had 320 respondents who each completed 16 choice sets. The results suggest that for the multinomial logit model (MNL) the design that is used at this stage is fairly unimportant. As the sample size gets smaller, however, differences between the designs become apparent. We also analysed the results using four different models which accommodate preference heterogeneity. We find that any of these models are able to predict choices more accurately for born in-sample and out-of-sample than the MNL model for the designs used here, and that the differences across designs arc larger for models with more parameters, although preliminary results suggest the gain appears to depend on the underlying preference structure.

Laver, K., Ratcliffe, J., George, S., Lester, L., Walker, R.A., Burgess, L.B. & Crotty, M. 2011, 'Early Rehabilitation Management After Stroke: What Do Stroke Patients Prefer?', Journal of Rehabilitation Medicine, vol. 43, no. 4, pp. 354-358.
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Background: Stroke rehabilitation is moving towards more intense therapy models that incorporate technologies such as robotics and computer games. It is unclear how acceptable these changes will be to stroke survivors, as little is known about which aspects of rehabilitation programmes are currently valued. Discrete choice experiments are a potential approach to assessing patient preferences, as they reveal the characteristics of programmes that are most important to consumers.Methods: A discrete choice experiment was presented as a face-to-face interview to assess the priorities and preferences of stroke survivors (n = 50, mean age 72 years) for alternative rehabilitation service configurations. The discrete choice experiment was presented to the participants while they were on the stroke rehabilitation ward (approximately 3-4 weeks following stroke).Results: Participants were highly focused on recovery and expressed strong preferences for therapy delivered one-to-one, but they did not favour very high intensity programmes (6 hours per day). While the attitudinal statements indicated high levels of agreement for programmes to incorporate the latest technology, the results from the discrete choice experiment indicated that participants were averse to computerdelivered therapy. Conclusion: Whilst rehabilitation therapy is highly valued, stroke survivors exhibited stronger preferences for low-in-tensity programmes and rest periods. High-intensity therapy protocols or approaches dependent on new technologies will require careful introduction to achieve uptake and acceptability.

Laver, K., Ratcliffe, J., George, S., Burgess, L.B. & Crotty, M. 2011, 'Is the Nintendo Wii Fit really acceptable to older people?: a discrete choice experiment', BMC Geriatrics, vol. 11, no. 64, pp. 1-6.
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Background Interactive video games such as the Nintendo Wii Fit are increasingly used as a therapeutic tool in health and aged care settings however, their acceptability to older people is unclear. The aim of this study was to determine the acceptability of the Nintendo Wii Fit as a therapy tool for hospitalised older people using a discrete choice experiment (DCE) before and after exposure to the intervention. Methods A DCE was administered to 21 participants in an interview style format prior to, and following several sessions of using the Wii Fit in physiotherapy. The physiotherapist prescribed the Wii Fit activities, supervised and supported the patient during the therapy sessions. Attributes included in the DCE were: mode of therapy (traditional or using the Wii Fit), amount of therapy, cost of therapy program and percentage of recovery made. Data was analysed using conditional (fixed-effects) logistic regression. Results Prior to commencing the therapy program participants were most concerned about therapy time (avoiding programs that were too intensive), and the amount of recovery they would make. Following the therapy program, participants were more concerned with the mode of therapy and preferred traditional therapy programs over programs using the Wii Fit. Conclusions The usefulness of the Wii Fit as a therapy tool with hospitalised older people is limited not only by the small proportion of older people who are able to use it, but by older people's preferences for traditional approaches to therapy. Mainstream media portrayals of the popularity of the Wii Fit with older people may not reflect the true acceptability in the older hospitalised population.

Putten, v.E., Jennings, S.M., Louviere, J.J. & Burgess, L.B. 2011, 'Tasmanian landowner preferences for conservation incentive programs: A latent class approach', Journal of Environmental Management, vol. 92, no. 10, pp. 2647-2656.
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An empirical model of landowners' conservation incentive program choice is developed in which information about landowners' socio-economic and property characteristics and their attitudes, is combined with incentive program attributes. In a Choice survey landowners were presented with the choice of two incentive programs modelled as 'bundles of attributes' mimicking a voluntary choice scenario. Landowner behaviour and decision and the type of conditions and regulations they preferred were analyzed. Based on choice survey data, landowner heterogeneity was accounted for using a latent class approach to estimate the preference parameters. Three latent classes of landowners with different attitudes to the role and outcome of establishing conservation reserves on private land were identified: multi-objective owners: environment owners: and production owners. Only a small proportion of landowners, mostly environment owners, would voluntarily join a program. Although compensation funding contributed to voluntary program choice for multi-objective owners and environment owners, welfare losses were around 4000 AUD per hectare, which is less than the average agricultural land value in Tasmania. Landowners for whom compensation funding contributed to voluntary program choice were also most likely to set aside land for conservation without payment. This raises the possibility that the government's compensation expenditure could potentially be either reduced or re-allocated to landowners who will not voluntarily take conservation action. Increasing participation in conservation incentive programs and minimizing the welfare losses associated with meeting conservation targets may be best achieved by offering programs that allow flexibility in terms of legal arrangements and other program attributes.

Ratcliffe, J., Couzner, L., Flynn, T.N., Sawyer, M., Stevens, K., Brazier, J.E. & Burgess, L.B. 2011, 'Valuing Child Health Utility 9D Health States with a young adolescent sample: a feasibility study to compare best worst discrete choice, standard gamble and time trade off methods.', Applied Health Economics and Health Policy, vol. 9, no. 1, pp. 15-27.
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QALYs are increasingly being utilized as a health outcome measure to calculate the benefits of new treatments and interventions within cost-utility analyses for economic evaluation. Cost-utility analyses of adolescent-specific treatment programmes are scant in comparison with those reported upon for adults and tend to incorporate the views of clinicians or adults as the main source of preferences. However, it is not clear that the views of adults are in accordance with those of adolescents on this issue. Hence, the treatments and interventions most highly valued by adults may not correspond with those most highly valued by adolescents. Ordinal methods for health state valuation may be more easily understood and interpreted by young adolescent samples than conventional approaches. The availability of young adolescent-specific health state values for the estimation of QALYs will provide new insights into the types of treatment programmes and health services that are most highly valued by young adolescents.

Bush, S.A., Burgess, L.B. & Street, D. 2010, 'Optimal designs for stated choice experiments that incorporate ties', Journal of Statistical Planning and Inference, vol. 140, no. 7, pp. 1712-1718.
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In 1970 Davidson generalised the Bradley-Terry model to allow respondents to say that the two options presented in a choice task were equally attractive. In this paper we extend this idea to the MNL model with m options in each choice set and we show that the optimal designs for the MNL model are also optimal in this setting.

Louviere, J.J., Islam, T., Wasi, N., Street, D. & Burgess, L.B. 2008, 'Designing Discrete Choice Experiments: Do Optimal Designs Come At A Price?', Journal of Consumer Research, vol. 35, no. 2, pp. 360-375.
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In discrete choice experiments, design decisions are crucial for determining data quality and costs. While high statistical efficiency designs are desirable, they may come at a price if they increase the cognitive burden for respondents. We address this problem by designing 44 experiments that systematically vary numbers of attributes and attribute level differences. Our results for two product categories suggest that respondents systematically are less consistent in answering choice questions as statistical efficiency increases. This relationship holds regardless of the number of attributes and is statistically significant even if one accommodates preference heterogeneity. Implications for practice and future research are discussed.

Louviere, J.J., Street, D., Burgess, L.B., Wasi, N., Islam, T. & Marley, A.A. 2008, 'Modeling the choices of individual decision-makers by combining efficient choice experiment designs with extra preference information', Journal of Choice Modelling, vol. 1, no. 1, pp. 128-163.
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Street, D. & Burgess, L.B. 2008, 'Some open combinatorial problems in the design of stated choice experiments', Discrete Mathematics, vol. 308, no. 13, pp. 2781-2788.
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Stated choice experiments are widely used in many areas and the optimal allocation of options to choice sets can make a substantial difference to the cost of running such an experiment. In this paper we describe some open problems in the design of optima

Burgess, L.B. & Street, D. 2006, 'The optimal size of choice sets in choice experiments', Statistics, vol. 40, no. 6, pp. 507-515.
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Inthis paper, we establish the optimal size of the choice sets in generic choice experiments for asymmetric attributes when estimating main effects only. We give an upper bound for the determinant of the information matrix when estimating main effects and all two-factor interactions for binary attributes. We also derive the information matrix for a choice experiment in which the choice sets are of different sizes and use this to determine the optimal sizes for the choice sets.

Burgess, L.B. & Street, D. 2005, 'Optimal designs for choice experiments with asymmetric attributes', Journal Of Statistical Planning And Inference, vol. 134, no. 1, pp. 288-301.
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In this paper we establish the form of the optimal design for choice experiments in which attributes need not have the same number of levels for testing main effects only, when there are k attributes, and all choice sets are of size m. We give a construc

Street, D., Burgess, L.B. & Louviere, J.J. 2005, 'Quick and easy choice sets: Constructing optimal and nearly optimal stated choice experiments', International Journal of Research in Marketing, vol. 22, no. 4, pp. 459-470.
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In this paper we compare a number of common strategies for constructing discrete choice experiments. Two of the strategies, including one based on theoretical constructions for optimal discrete choice experiments, produce designs that are better than those that come about from random grouping and from using the LMA construction. A simple account of this theoretical construction is given

Street, D. & Burgess, L.B. 2004, 'Optimal and near-optimal pairs for the estimation of effects in 2-levels choice experiments', Journal of Statistical Planning and Inference, vol. 118, pp. 185-199.
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This paper gives constructions for optimal and near-optimal sets of pairs for the estimation of main effects, and for the estimation of main effects and two factor interactions, in forced choice experiments in which all attributes have two levels. The number of pairs inthe sets is much smaller than that in previulsy constructed optimal 2-level choice experiments

Street, D. & Burgess, L.B. 2004, 'Optimal stated preference choice experiments when all choice sets contain a specific option', Statistical Methodology, vol. 1, pp. 37-45.
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Stated preference choice experiments are routinely used in many areas from marketing to medicine. While results on the optimal choice sets to present for the forsed choice setting have been determined in a variety of situations, no results have appeared to date on the optimal choice sets to use when either all choice sets are to contain a common base alternative or when all choice sets contain a "none of these" option. These problems are considered in this paper.

Burgess, L.B., Street, D. 2003, 'Optimal designs for 2(k) choice experiments', Communications In Statistics-theory And Methods, vol. 32, no. 11, pp. 2185-2206.
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