Our paper 'Sample size requirements for discrete choice experiments in health care: a practical guide' (The Patient, 2015) explains, step-by-step, how the minimum sample size requirement for a DCE study can be calculated and provides a general R-code. In that paper a ­DCE about patients’ preferences for preventive osteoporosis drug treatment is used as an illustration (its DCE-design and R-code can be downloaded by opening the link).