Criteria for Causality: Bradford Hill Criteria - II

The Bradford Hill criteria for causality include biological gradient, plausibility, coherence, experiment, and analogy.

The biological gradient, or dose-response relationship, suggests that increasing exposure should lead to an increased risk of the effect.

For example, the dustier the workplace, the higher the risk of developing dust allergies.

According to the plausibility criterion, the association between cause and effect must be biologically plausible based on current understanding.

For instance, the carcinogenic effects of tobacco or radiation are biologically plausible.

The coherence criterion states that the interpretation of cause-and-effect data should not contradict the known natural history and biology of the disease.

The experiment criterion suggests examining causal relationships through appropriate experimentation, though not all causal relationships can be tested this way.

Lastly, the analogy criterion allows attributing an effect to a cause by analogy with established causal relationships.

For example, the teratogenic effects of thalidomide provided an analogy for suspecting that other drugs might also cause congenital disabilities when taken during pregnancy.