Lecture 7.2: Causation

Question 1

What is Causation?

Answer 1

• A factor that plays a role in bringing about
  disease

Question 2

A Causal Factor may be Necessary or Sufficient. What do these mean?

Answer 2

• Necessary: X must be present for Y to happen
• Sufficient: if X is present, Y will happen

Question 3

Bradford Hill’s Criteria for Causation (1965) (7)

Answer 3

• Strength of association
• Dose-Response relationship
• Lack of temporal ambiguity
• Consistency of findings
• Biological plausibility
• Coherence of evidence
• Specificity of association

Question 4

What are the 3 Man Types of Bias?

Answer 4

• Information Bias
• Selection Bias
• Confounding Bias

Question 5

What do we try to avoid in Information Bias?

Answer 5

Measurement error of exposure or disease

Question 6

What do we try to avoid in Selection Bias?

Answer 6

Does selection of the control/reference group depend on outcome and the exposure of interest

Question 7

What do we try to avoid in Confounding Bias?

Answer 7

Lack of comparability (lack of exchangeability) between exposed and unexposed populations

Question 8

What is a Differential (Systematic) Error?

Answer 8

Use of an invalid measures that misclassifies cases in one direction and misclassifies controls in another

Question 9

What is a Random (Non-Differential) Error?

Answer 9

Use of invalid outcome measure that equally misclassifies cases and controls