In terms of explaining the probability of assignment to trial arms in consent forms, which is true? Neither FDA nor ICH require statements about the probability for random assignment to each treatment arm or the use of a placebo arm. FDA requires the probability to be expressed as a percentage chance. The probability of assignment should always be stated as being "like the flip of a coin" because subjects can understand that example. ICH notes that it should be included, but does not specify how the information should be presented