Principles of Causation

In the epidemiological literature, there are 3 major sets of criteria for the determination of causation, the Bradford Hill criteria2, the Hume3 criteria, and the Mill4 criteria. Since they are all relatively similar, this course will focus on the more established Bradford Hill criteria typically used by epidemiologists.

In the early 1950’s there was much discussion about whether smoking and lung cancer were related. Dr. A. Bradford Hill, a medical scientist and statistician in London England, developed a set of criteria to test this assumption. Along with the aid of his colleague Dr. Richard Doll, these criteria were applied and they were able to prove that indeed smoking was the cause of lung cancer. Since then, the Bradford Hill criteria have been used as the standard in the interpretation of causality by the public health and medical community. The criteria are as follows:

Temporality, Plausibility, Consistency, Strength of the Association, Dose-response relationship (Biological Gradient), Specificity, Experiment, Coherence, and Analogy (Figure 1).

Figure 1. Bradford Hill Criteria.
Bradford Hill Criteria