“…13 The observation that among those with a preference, roughly twice as many veterans preferred the opt-in model has been echoed elsewhere. 14,15 Assuming that the percentages of respondents who said they would participate under the respective models actually applied to the MVP study, recruiting 1,000,000 subjects would require asking 1,450,000 veterans using an optout method or 1,250,000 veterans using an opt-in method. In practice, however, the opt-out rate of one large cohort study has been reported to be <5%, and, in a small, randomized-controlled trial of opt-in and opt-out enrollment models, participants in the opt-out group were more satisfied than those who were asked to opt in.…”