Question

Causation and Association are two important concepts in Epidemiology. Discuss criteria for the evaluation of casusation in epidemiological studies.

Answer 1

Causation:

It is an essential concept in epidemiology. The Bradford Hill criteria is used for teh evaluation of causation in epidemiology. This criteria is a group of 9 principles. This criteria outlines the minimal conditions needed to establish a causal relationship between two items. They are devised as a way of determining the causal link between a specific factor and a disease.

The criteria established by Hill was developed as a research tool in the medical sciences, it is equally applicable to sociology, anthropology and other social sciences, which attempt to establish causal relationships among social phenomena. Hill's Criteria simply provides an additional valuable measure by which to evaluate the many theories and explanations proposed within the social sciences.

He demonstrated the connection between cigarette smoking and lung cancer. The list of the criteria that is used consists of nine prnciples which are listed below:

1. Strength: A small association does not mean that there is not a causal effect, though the larger the association, the more likely that it is causal.
2. Consistency: Consistent findings observed by different persons in different places with different samples strengthens the likelihood of an effect.
3. Specificity: Causation is likely if there is a very specific population at a specific site and disease with no other likely explanation. The more specific an association between a factor and an effect is, the bigger the probability of a causal relationship.
4. Temporality: The effect has to occur after the cause.
5. Biological gradient: Greater exposure should generally lead to greater incidence of the effect.
6. Plausibility: A plausible mechanism between cause and effect is helpful.
7. Coherence: Coherence between epidemiological and laboratory findings increases the likelihood of an effect.
8. Experiment: "Occasionally it is possible to appeal to experimental evidence".
9. Analogy: The effect of similar factors may be considered.