%0 Journal Article %T Letter to the Editor: Preference option randomized design (PORD) for comparative effectiveness research: Statistical power for testing comparative effect, preference effect, selection effect, intent %A Gordon Guyatt %A Kameshwar Prasad %A Petra Macaskill %A Richard Cook %A Robin Turner %A SD Walter %J Statistical Methods in Medical Research %@ 1477-0334 %D 2019 %R 10.1177/0962280218767691 %U https://journals.sagepub.com/doi/full/10.1177/0962280218767691