Randomized controlled trials (RCTs) of a new investigational drug often include active as well as placebo control arms. The active arm, comprising an approved treatment for the indication under study, along with the placebo arm, are together required to establish assay sensitivity; if the active treatment outperforms placebo, as expected, the results of the RCT can be further interpreted, but if the active treatment is no better than placebo (such as because of ceiling or floor effects), the RCT is a failed trial. The concepts involved are explained from scientific and ethical perspectives.

中文翻译：

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天花板效应、地板效应以及活性和安慰剂对照组在研究药物随机对照试验中的重要性

新研究药物的随机对照试验 (RCT) 通常包括活性和安慰剂对照组。活性组（包括针对所研究适应症的批准治疗）与安慰剂组一起需要建立测定灵敏度；如果积极治疗优于安慰剂，正如预期的那样，可以进一步解释 RCT 的结果，但如果积极治疗并不比安慰剂好（例如因为天花板或地板效应），则 RCT 是失败的试验。所涉及的概念从科学和伦理的角度进行解释。