EPID 7120: Epidemiologic Methods 2,
Final Exam Prep
1. What are two common models of causation?
o Model of sufficient and component causes and the counterfactual.
2. What are DAGs?
o Visual presentation of causal assumptions.
3. What are the Bradford Hill Criteria?
o Strength, consistency, temporality, biological gradient, coherence,
experiment, analogy, specificity, plausibility; not a checklist.
4. What is strength in the Bradford Hill Criteria?
o 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.
5. What is consistency in the Bradford Hill Criteria?
o Consistent findings observed by different people in different places with
different samples strengthen the likelihood of an effect.
6. What is temporality in the Bradford Hill Criteria?
o The effect has to occur after the cause.
7. What is biological gradient in the Bradford Hill Criteria?
o Greater exposure should generally lead to greater incidence of the effect.
In other cases, greater exposure leads to lower incidence.
8. What is coherence in the Bradford Hill Criteria?
o Coherence between epidemiological and laboratory findings increases the
likelihood of an effect but lack of such evidence cannot nullify the
epidemiological effect on associations.
9. What is experiment in the Bradford Hill Criteria?
o Occasionally it is possible to appeal to experimental evidence.
10. What is analogy in the Bradford Hill Criteria?
, o The effect of similar factors may be considered.
11. What is specificity in the Bradford Hill Criteria?
o Causation is likely if there is a very specific population, at a specific site,
with a specific disease with no other likely explanation.
12. What is plausibility in the Bradford Hill Criteria?
o A plausible mechanism between cause and effect is helpful.
13. What are the types of causal relationships?
o Direct & indirect.
14. What is a cause?
o An event, condition, or characteristic that preceded the outcome, and had
the event, condition, or characteristic been different in some way, the
outcome would not have occurred at all or not for some time later.
15. What is a sufficient cause?
o A minimal set of conditions and events that are sufficient for the outcome
to occur (e.g., exposure by itself leads to an outcome or set of exposures
together leads to the outcome).
16. What is a necessary cause?
o A particular type of component cause that is required for the outcome to
occur (remove exposure and do not get the outcome).
17. What is the counterfactual?
o What you do not actually observe (e.g., Does Lipitor change the risk of
heart disease? The heart disease that would have been observed if these
persons had not taken Lipitor = counterfactual).
18. What are Directed Acyclic Graphs (DAGs)?
o Visual representations of "the world" that use a common set of "rules" to
facilitate communication and collaboration among investigators.
19. What are the rules of causal diagrams?
o
, 1. No cycles, 2) Nodes (measured and unmeasured variables), 3) Path
(association), 4) Directed path (theorized causation). For the
diagram to be "causal," it must include ALL common causes of
every variable on the diagram.
20. What is an open pathway?
o A -> B -> C (e.g., obesity to diabetes to cardiovascular disease).
21. What is a blocked pathway?
o A -> B <- C (e.g., obesity -> diabetes <- congenital hyperinsulinism).
22. What is a collider?
o A node with two arrowheads pointing at it.
23. What is a descendant?
o E (diabetes) is a descendant of B (glycated hemoglobin A1c).
24. What are mediators?
o Affected by exposure AND on the causal pathway between exposure &
disease AND cause of disease; they translate part of the effect of exposure
on disease; we do not want to adjust for mediators.
25. What are confounders?
o Associated with the exposure, AND associated with disease, AND not on
the causal pathway; often want to adjust for confounders.
26. What is a direct causal pathway?
o E.g., obesity causes MI.
27. What is an indirect causal path?
o Connects exposure and outcome of interest through other variable(s) (e.g.,
obesity causes MI through High BP).
28. What is confounding?
o Distortion of the estimated effect of an exposure on an outcome due to
the presence of a common cause of the exposure and the outcome.
29. What are the major problems for causal inference?
o
Final Exam Prep
1. What are two common models of causation?
o Model of sufficient and component causes and the counterfactual.
2. What are DAGs?
o Visual presentation of causal assumptions.
3. What are the Bradford Hill Criteria?
o Strength, consistency, temporality, biological gradient, coherence,
experiment, analogy, specificity, plausibility; not a checklist.
4. What is strength in the Bradford Hill Criteria?
o 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.
5. What is consistency in the Bradford Hill Criteria?
o Consistent findings observed by different people in different places with
different samples strengthen the likelihood of an effect.
6. What is temporality in the Bradford Hill Criteria?
o The effect has to occur after the cause.
7. What is biological gradient in the Bradford Hill Criteria?
o Greater exposure should generally lead to greater incidence of the effect.
In other cases, greater exposure leads to lower incidence.
8. What is coherence in the Bradford Hill Criteria?
o Coherence between epidemiological and laboratory findings increases the
likelihood of an effect but lack of such evidence cannot nullify the
epidemiological effect on associations.
9. What is experiment in the Bradford Hill Criteria?
o Occasionally it is possible to appeal to experimental evidence.
10. What is analogy in the Bradford Hill Criteria?
, o The effect of similar factors may be considered.
11. What is specificity in the Bradford Hill Criteria?
o Causation is likely if there is a very specific population, at a specific site,
with a specific disease with no other likely explanation.
12. What is plausibility in the Bradford Hill Criteria?
o A plausible mechanism between cause and effect is helpful.
13. What are the types of causal relationships?
o Direct & indirect.
14. What is a cause?
o An event, condition, or characteristic that preceded the outcome, and had
the event, condition, or characteristic been different in some way, the
outcome would not have occurred at all or not for some time later.
15. What is a sufficient cause?
o A minimal set of conditions and events that are sufficient for the outcome
to occur (e.g., exposure by itself leads to an outcome or set of exposures
together leads to the outcome).
16. What is a necessary cause?
o A particular type of component cause that is required for the outcome to
occur (remove exposure and do not get the outcome).
17. What is the counterfactual?
o What you do not actually observe (e.g., Does Lipitor change the risk of
heart disease? The heart disease that would have been observed if these
persons had not taken Lipitor = counterfactual).
18. What are Directed Acyclic Graphs (DAGs)?
o Visual representations of "the world" that use a common set of "rules" to
facilitate communication and collaboration among investigators.
19. What are the rules of causal diagrams?
o
, 1. No cycles, 2) Nodes (measured and unmeasured variables), 3) Path
(association), 4) Directed path (theorized causation). For the
diagram to be "causal," it must include ALL common causes of
every variable on the diagram.
20. What is an open pathway?
o A -> B -> C (e.g., obesity to diabetes to cardiovascular disease).
21. What is a blocked pathway?
o A -> B <- C (e.g., obesity -> diabetes <- congenital hyperinsulinism).
22. What is a collider?
o A node with two arrowheads pointing at it.
23. What is a descendant?
o E (diabetes) is a descendant of B (glycated hemoglobin A1c).
24. What are mediators?
o Affected by exposure AND on the causal pathway between exposure &
disease AND cause of disease; they translate part of the effect of exposure
on disease; we do not want to adjust for mediators.
25. What are confounders?
o Associated with the exposure, AND associated with disease, AND not on
the causal pathway; often want to adjust for confounders.
26. What is a direct causal pathway?
o E.g., obesity causes MI.
27. What is an indirect causal path?
o Connects exposure and outcome of interest through other variable(s) (e.g.,
obesity causes MI through High BP).
28. What is confounding?
o Distortion of the estimated effect of an exposure on an outcome due to
the presence of a common cause of the exposure and the outcome.
29. What are the major problems for causal inference?
o
