Convincing studies of drugs and surgical procedures usually come only from randomized trials, in which patients receive treatment or don’t according to a process analogous to a coin flip. Well-conducted randomized trials incorporate additional safeguards against bias, including use of placebo medication that allows investigators to blind patients and caregivers to whether patients are, or are not, receiving active treatment.
对于药物和手术程序令人信服的研究通常只会从随机试验中产生。在随即试验中，病人接受或不接受治疗是通过一个类似投硬币来决定的程序来确定的。实施良好的随机试验会对避免偏差现象注入额外的保障，包括使用安慰剂药物使调查者可以让病人及看护人不清楚到底是否正在接受积极治疗。