偏倚指在医学研究中由于某种或某些因素的影响,使研究结论与真实情况存在系统误差,有时可能会夸大、有时又可能缩小研究结果的真实性。临床研究从设计到实施及最后的资料分析和结论的推导中的任何一个环节都可能出现偏倚。根据研究中出现的阶段不同可归为三大类:选择性偏倚、信 Bias refers to the fact that there is a systematic error between the conclusion of the research and the real situation in the medical research due to some or some factors, which may sometimes be exaggerated and may sometimes reduce the authenticity of the research results. Clinical studies can be biased at any point in the design-to-implementation and final derivation of data analysis and conclusions. Depending on the stage of the study, there are three broad categories: selective bias, letter