Causation and Association

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Associations are first identified, with causation being shown second. Associations are observed, while causation is inferred. Proving causality can be done with Hill's criteria.






Associations, or relationships, are statistical dependence between two or more events, characteristics, or other variables. However, it does not imply causation.

After designing a study to determine whether an association exists, work needs to be done to test what sort of relationship exists.

There are three different types of associations:

Measuring Associations

Associations can be measured in two ways.

Relative measures are presented as:

Absolute Measures are presented as:

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Causes are complex and almost always act in concert with other factors that have various strengths and directions.

Indirect causes can include risk factors, but not all risk factors are causal.


Four types of causal factors

Necessary and sufficient

Necessary but not sufficient

Sufficient but not necessary

Neither sufficient nor necessary

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Proving Causality - Hill's Criteria for Causation

  1. temporal relationship: the only absolutely neccessary criterion
  2. strength of the association
  3. dose-response relationship
  4. consistency
  5. experiemental
  6. biolgicial plausibility
  7. coherence
  8. specificity

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Resources and References

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