文档介绍：System error 系统误差
Biases in epidemiological studies
流行病学研究中的偏倚
Learning Objectives 学****目标
When you pleted this session you will be able to:
Understand the difference between error due to chance versus bias
理解偏移误差和偶然性误差的区别
Describe the major classes of bias and how they relate to epidemiologic study designs
描述主要类别的偏倚以及其与流行病学研究设计的关系
Suggest ways to minimize the occurrence of error
建议减少误差发生的方法
Identify sources of error in a study and describe impact on observed results
指出研究中的误差来源并描述其对观察结果的影响
Overview 概述
Primary objective in analytic epidemiology: 分析性流行病学的主要目标是:
Is the observed association between exposure and disease causal? 决定所观察到的暴露因素和疾病是否有因果关系?
Potential for error due to chance or bias must be anticipated in the: 需预料到潜在可能发生的偶然性错误或偏移:
Design 设计
Conduct 执行
Analysis 分析
Interpretation of epidemiologic studies
对流行病学研究的解释
Sources of Error 误差的来源
Chance 偶然
Random variation in selection of study participants 选择研究参与者过程中的随机变化
Bias (systematic error) 偏移(系统误差)
Selection bias 选择性偏移
Collection bias 收集偏移
Chance 偶然性误差
Smaller samples are less likely to represent the population of interest by chance alone 较小的样本量只因偶然代表特定人群的可能性较低
Estimates from small samples have more variability (less reliability) than estimates from larger samples
小样本量与大样本量相比,估算的变异度更高(可靠性更低)
All conclusions based on samples have some potential for error due to chance
所有根据样本量所得出的结论都有一定的潜在偶然性误差
Definition of bias 偏移的定义
Any systematic error in an epidemiological study that results in an incorrect estimate of the association between exposure and risk of disease
流行病学研究中任何导致错误评估暴露因素和疾病风险的关联的系统误差。
Taken from JJ Schlesselman
How to understand the term systematic? 如何理解‘系统性’这个词?
Error systematically done in the same way 以相同方式系统性的产生误差
Differential misclassification 差异性错分
Error of the system 系统误差
Built in misconception of the protocol 来源于研究方案中的错误理解
Biases
Types of Bias or Systematic Error 偏移的种类(系统误差)
Selection biases: the way subjects enter a study 选择性偏移:研究对象被选入研究的方式
Related to disease status in a cohort st