Final answer:
Bradford Hill's criteria for causation are guidelines that help determine if an association observed in epidemiological studies is likely causal. Strength of association, consistency, and other factors such as temporality, biological gradient, plausibility, coherence, experiment, and analogy are considered as part of the evaluation process for causation.
Step-by-step explanation:
Sir Austin Bradford Hill established a set of criteria to assist in the evaluation of whether associations observed in epidemiological studies can be deemed causal. These criteria, which are nonetheless still considered a cornerstone in public health research to evaluate causality, include:
- Strength of association: This considers the size of the relationship between a factor and an outcome. A larger association suggests but does not prove causality.
- Consistency: The observed association is replicated in different studies and populations, which supports a causal effect.
- Specificity: The factor is associated with a particular disease or outcome rather than a wide range of outcomes.
- Temporality: The cause must precede the effect; essentially, exposure to the risk factor must occur before the disease develops.
- Biological gradient: Also known as dose-response relationship; an increasing amount of exposure increases the risk.
- Plausibility: The association agrees with the currently accepted understanding of pathological processes.
- Coherence: The findings do not seriously conflict with the generally known facts of the natural history and biology of the disease.
- Experiment: Causal relationships are supported by experiments or intervention studies.
- Analogy: The effects of similar factors may be considered in supporting evidence for causality.
These criteria are not hard-and-fast rules, but rather a framework to guide research and interpretation of epidemiological data.