The Effect of Including an Opt-Out Option in Discrete Choice Experiments

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Abstract

Objective

to determine to what extent the inclusion of an opt-out option in a DCE may have an effect on choice behaviour and therefore might influence the attribute level estimates, the relative importance of the attributes and calculated trade-offs.

Methods

781 Dutch Type 2 Diabetes Mellitus patients completed a questionnaire containing nine choice tasks with an opt-out option and nice forced choice tasks. Mixed-logit models were used to estimate the relative importance of the five lifestyle program related attributes that were included. Willingness to pay (WTP) values were calculated and it was tested whether results differed between respondents who answered the choice tasks with an opt-out option in the first or second part of the questionnaire.

Results

21.4% of the respondents always opted out. Respondents who were given the opt-out option in the first part of the questionnaire as well as lower educated respondents significantly more often opted out. For both the forced and unforced choice model, different attributes showed significant estimates, the relative importance of the attributes was equal. However, due to differences in relative importance weights, the WTP values for the PA schedule differed significantly between both datasets.

Conclusions

Results show differences in opting out based on the location of the opt-out option and respondents' educational level; this resulted in small differences between the forced and unforced choice model. Since respondents seem to learn from answering forced choice tasks, a dual response design might result in higher data quality compared to offering a direct opt-out option. Future research should empirically explore how choice sets should be presented to make them as easy and less complex as possible in order to reduce the proportion of respondents that opts-out due to choice task complexity. Moreover, future research should debrief respondents to examine the reasons for choosing the opt-out alternative.

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Most cited references 23

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[Measuring the quality of life in economic evaluations: the Dutch EQ-5D tariff].

L Lamers, P F M Stalmeier, J. McDonnell … (2005)

To value EQ-5D health states by a general Dutch public. EQ-5D is a standardised questionnaire that is used to calculate quality-adjusted life-years for cost-utility analysis. Descriptive. A sample of 309 Dutch adults from Rotterdam and surroundings was asked to value 17 EQ-5D health states using the time trade-off method. Regression analysis was applied to the valuations of these 17 health states. By means of the estimated regression coefficients, which together constitute the so-called Dutch tariff, valuations can be determined for all possible EQ-5D health states. These values reflect the relative desirability of health states on a scale where 1 refers to full health and 0 refers to death. Societal valuations are necessary in order to correct life-years for the quality of life. Complete data were obtained from 298 persons. Theywere representative for the Dutch population as far as age, gender and subjective health were concerned, but had a somewhat higher educational level. The estimated Dutch EQ-5D tariff revealed that the respondents assigned the most weight to (preventing) pain and anxiety or depression, followed by mobility, self-care and the activities of daily living. The Dutch tariff differed from the UK ('Measurement and Valuation of Health') tariff, which is currently used in Dutch cost-utility analyses. Compared to UK respondents, Dutch respondents assigned more weight to anxiety and depression and less weight to the other dimensions. Conclusion. The valuation of health states by this representative Dutch study group differed from the valuation that is currently used in Dutch cost-utility analyses.

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Exercise for type 2 diabetes mellitus.

Diana Thomas, Elizabeth J Elliott, Geraldine Naughton (2009)

Exercise is generally recommended for people with type 2 diabetes mellitus. However, some studies evaluate an exercise intervention including diet or behaviour modification or both, and the effects of diet and exercise are not differentiated. Some exercise studies involve low participant numbers, lacking power to show significant differences which may appear in larger trials. To assess the effects of exercise in type 2 diabetes mellitus. Trials were identified through the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and manual searches of bibliographies. Date of last search was March 3, 2005. All randomised controlled trials comparing any type of well-documented aerobic, fitness or progressive resistance training exercise with no exercise in people with type 2 diabetes mellitus. Two authors independently selected trials, assessed trial quality and extracted data. Study authors were contacted for additional information. Any information on adverse effects was collected from the trials. Fourteen randomised controlled trials comparing exercise against no exercise in type 2 diabetes were identified involving 377 participants. Trials ranged from eight weeks to twelve months duration. Compared with the control, the exercise intervention significantly improved glycaemic control as indicated by a decrease in glycated haemoglobin levels of 0.6% (-0.6 % HbA(1c), 95% confidence interval (CI) -0.9 to -0.3; P < 0.05). This result is both statistically and clinically significant. There was no significant difference between groups in whole body mass, probably due to an increase in fat free mass (muscle) with exercise, as reported in one trial (6.3 kg, 95% CI 0.0 to 12.6). There was a reduction in visceral adipose tissue with exercise (-45.5 cm(2), 95% CI -63.8 to -27.3), and subcutaneous adipose tissue also decreased. No study reported adverse effects in the exercise group or diabetic complications. The exercise intervention significantly increased insulin response (131 AUC, 95% CI 20 to 242) (one trial), and decreased plasma triglycerides (-0.25 mmol/L, 95% CI -0.48 to -0.02). No significant difference was found between groups in quality of life (one trial), plasma cholesterol or blood pressure. The meta-analysis shows that exercise significantly improves glycaemic control and reduces visceral adipose tissue and plasma triglycerides, but not plasma cholesterol, in people with type 2 diabetes, even without weight loss.

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Conjoint Analysis Applications in Health - How are Studies being Designed and Reported?: An Update on Current Practice in the Published Literature between 2005 and 2008.

A. Brett Hauber, Ken Fyie, Sherri Lovelace-Cameron … (2010)

Despite the increased popularity of conjoint analysis in health outcomes research, little is known about what specific methods are being used for the design and reporting of these studies. This variation in method type and reporting quality sometimes makes it difficult to assess substantive findings. This review identifies and describes recent applications of conjoint analysis based on a systematic review of conjoint analysis in the health literature. We focus on significant unanswered questions for which there is neither compelling empirical evidence nor agreement among researchers.We searched multiple electronic databases to identify English-language articles of conjoint analysis applications in human health studies published since 2005 through to July 2008. Two independent reviewers completed the detailed data extraction, including descriptive information, methodological details on survey type, experimental design, survey format, attributes and levels, sample size, number of conjoint scenarios per respondent, and analysis methods. Review articles and methods studies were excluded. The detailed extraction form was piloted to identify key elements to be included in the database using a standardized taxonomy.We identified 79 conjoint analysis articles that met the inclusion criteria. The number of applied studies increased substantially over time in a broad range of clinical applications, cancer being the most frequent. Most used a discrete-choice survey format (71%), with the number of attributes ranging from 3 to 16. Most surveys included 6 attributes, and 73% presented 7-15 scenarios to each respondent. Sample size varied substantially (minimum = 13, maximum = 1258), with most studies (38%) including between 100 and 300 respondents. Cost was included as an attribute to estimate willingness to pay in approximately 40% of the articles across all years.Conjoint analysis in health has expanded to include a broad range of applications and methodological approaches. Although we found substantial variation in methods, terminology, and presentation of findings, our observations on sample size, the number of attributes, and number of scenarios presented to respondents should be helpful in guiding researchers when planning a new conjoint analysis study in health.

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Author and article information

Contributors

D. William Cameron: Role: Editor

Journal

Journal ID (nlm-ta): PLoS One

Journal ID (iso-abbrev): PLoS ONE

Journal ID (publisher-id): plos

Journal ID (pmc): plosone

Title: PLoS ONE

Publisher: Public Library of Science (San Francisco, USA )

ISSN (Electronic): 1932-6203

Publication date Collection: 2014

Publication date (Electronic): 3 November 2014

Volume: 9

Issue: 11

Electronic Location Identifier: e111805

Affiliations

[1 ]Centre for Nutrition, Prevention and Health Services, National Institute for Public Health and the Environment, Bilthoven, The Netherlands

[2 ]Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands

[3 ]Department of Public Health, Erasmus MC, University Medical Center, Rotterdam, The Netherlands

University of Ottawa, Canada

Author notes

* E-mail: jorien.veldwijk@ 123456rivm.nl

Competing Interests: The authors have declared that no competing interests exist.

Conceived and designed the experiments: JV MSL EWBG HAS GAW. Performed the experiments: JV MSL GAW. Analyzed the data: JV MSL EWBG GAW. Contributed reagents/materials/analysis tools: JV MSL EWBG GAW. Wrote the paper: JV MSL EWBG HAS GAW.

Article

Publisher ID: PONE-D-14-15903

DOI: 10.1371/journal.pone.0111805

PMC ID: 4218820

PubMed ID: 25365169

SO-VID: afb594c7-5bfb-4223-9f0d-4ced3b3e61e6

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

History

Date received : 9 April 2014

Date accepted : 6 October 2014

Page count

Pages: 9

Funding

This study was funded by the Strategic Research RIVM (SOR) of the National Institute for Public Health and the Environment (to MSL and GAW). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Custom metadata

Data Availability The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper. Original data are available from DANS Data Archiving and Networked Services, which is a stable and public repository. The Dutch online archiving system Data Archiving and Networked Services (DANS), offers access to thousands of datasets in the humanities, the social sciences and other disciplines ( https://easy.dans.knaw.nl/ui/datasets/id/easy-dataset:58687). A persistent identifier of this study is: http://persistent-identifier.nl/?identifier=urn:nbn:nl:ui:13-5ovx-16.

The Effect of Including an Opt-Out Option in Discrete Choice Experiments

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Abstract

Objective

Methods

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PLOS Climate

Most cited references 23

[Measuring the quality of life in economic evaluations: the Dutch EQ-5D tariff].

Exercise for type 2 diabetes mellitus.

Conjoint Analysis Applications in Health - How are Studies being Designed and Reported?: An Update on Current Practice in the Published Literature between 2005 and 2008.

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