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→Relative importance and observational studies
Two other lines of reasoning question RCTs' contribution to scientific knowledge beyond other types of studies:
Two other lines of reasoning question RCTs' contribution to scientific knowledge beyond other types of studies:
* If study designs are ranked by their potential for new discoveries, then anecdotal evidence would be at the top of the list, followed by observational studies, followed by RCTs.
* RCTs may be unnecessary for treatments that have dramatic and rapid effects relative to the expected stable or progressively worse natural course of the condition treated. One example is combination chemotherapy including cisplatin for metastatic testicular cancer, which increased the cure rate from 5% to 60% in a 1977 non-randomized study.
2000年发表在《新英格兰医学杂志》上的两项研究发现，观察性研究和随机对照试验总体上产生了相似的结果。2000年研究结果的作者质疑“观察性研究不应用于定义循证医疗”以及随机对照试验的结果是“最高等级的证据”的观点。然而，2001年发表在《美国医学协会杂志》上的一项研究得出结论，观察性研究和随机对照试验之间“确实会出现超越偶然的差异，估计治疗效果的差异非常普遍”。
另外两条推理路线质疑随机对照试验对科学知识的贡献超过了其他类型的研究:
* If study designs are ranked by their potential for new discoveries, then anecdotal evidence would be at the top of the list, followed by observational studies, followed by RCTs.
* If study designs are ranked by their potential for new discoveries, then anecdotal evidence would be at the top of the list, followed by observational studies, followed by RCTs.
* RCTs may be unnecessary for treatments that have dramatic and rapid effects relative to the expected stable or progressively worse natural course of the condition treated. One example is combination chemotherapy including cisplatin for metastatic testicular cancer, which increased the cure rate from 5% to 60% in a 1977 non-randomized study.
* RCTs may be unnecessary for treatments that have dramatic and rapid effects relative to the expected stable or progressively worse natural course of the condition treated. One example is combination chemotherapy including cisplatin for metastatic testicular cancer, which increased the cure rate from 5% to 60% in a 1977 non-randomized study.
The intervention:
The intervention:
# Has not been applied to all members of a unique group of people (e.g. the population of a whole country, all employees of a unique organisation etc.)
# Has not been applied to all members of a unique group of people (e.g. the population of a whole country, all employees of a unique organisation etc.)
# Is applied in a context or setting similar to that which applies to the control group
# Is applied in a context or setting similar to that which applies to the control group
And the causal mechanisms:
And the causal mechanisms:
# Are either known to the researchers, or else all possible alternatives can be tested
# Are either known to the researchers, or else all possible alternatives can be tested
# Do not involve significant feedback mechanisms between the intervention group and external environments
# Do not involve significant feedback mechanisms between the intervention group and external environments