TY - JOUR T1 - Sample sizes based on three popular indices of risks JF - General Psychiatry JO - Gen Psych DO - 10.1136/gpsych-2018-100011 VL - 31 IS - 3 SP - e100011 AU - Hongyue Wang AU - Bokai Wang AU - Xin M Tu AU - Jinyuan Liu AU - Changyong Feng Y1 - 2018/12/01 UR - http://gpsych.bmj.com/content/31/3/e100011.abstract N2 - Sample size justification is a very crucial part in the design of clinical trials. In this paper, the authors derive a new formula to calculate the sample size for a binary outcome given one of the three popular indices of risk difference. The sample size based on the absolute difference is the fundamental one, which can be easily used to derive sample size given the risk ratio or OR. ER -