Example of Misclassification Bias

Non-Differential Exposure - Imperfect Sensitivity

Lead Author(s): Jeff Martin, MD

Measurement bias is affected by imperfect sensitivity of exposure variables.

Imperfect Sensitivity of Exposure Variables

In the diagram above the source population is on the top left and our study sample is on the bottom right.

Study - Alcohol Abuse

Consider as an example of a case-control study of some disease and the exposure under study is alcohol abuse.

Misclassification of Exposure

Non-Differential Misclassification of Exposure

Again, some truly exposed persons are misclassified as unexposed.

Imperfect Sensitivity - Bias the OR towards the Null Hypothesis


In the top panel above is the truth where there is no misclassification of exposure - What happens in the presence of 70% sensitivity in exposure classification?

Bias Towards the Null Hypothesis

This illustrates the effect of non-differential misclassification of exposure in the presence of 2 exposure categories -