Chapter 14: From Association to Causation

Question 1

What is causality?

Answer 1

Causality is the relationship between two events or variables.

Question 2

What study design does epidemiologist use?

Answer 2

They use natural experiments.

Question 3

Why is natural experiments ethical?

Answer 3

Natural experiments are ethical because you are observing someone who presently has the disease how they are affected by the disease rather than having to affect people with disease just to study how it affects them.

Question 4

What is real association?

Answer 4

Demonstrates that there is a causal association: association of exposure and the exposure that includes development of the disease.

Question 5

What is spurious association?

Answer 5

Demonstrates that is noncausal association between exposure, due to confounding factors that contribute to the disease.

Question 6

True or false are causal pathways direct and indirect?

Answer 6

True

Question 7

What are direct causal pathways?

Answer 7

A factor that directly causes a disease without any intermediate steps or factors.

Question 8

What are indirect pathways?

Answer 8

A factor that causes a disease but only through an intermediate step or steps.

Question 9

If a relationship is causal, what are the four types of causal relationship that are possible?

Answer 9

• Necessary and sufficient
• Necessary but not sufficient
• Sufficient but not necessary
• Sufficient not necessary

Question 10

What is necessary and sufficient?

Answer 10

The factor is both necessary and sufficient for producing the disease.
(without the factor present the disease will never develop/with the factor present the disease will always develop)

Question 11

True or false, necessary and sufficient often happen

Answer 11

False, necessary and sufficient rarely happen because you can’t determine who will and will not get the disease.

Question 12

What is necessary but not sufficient?

Answer 12

Factor is necessary but each factor alone is not sufficient to cause the disease. Multiple factors are required, usually in a very specific order. (need exposure before you get agent)

Question 13

What is sufficient but not necessary?

Answer 13

One factor can produce the disease but so can other factor. These other factors can act alone to cause the disease. (the criterion of the sufficient is rarely met by a single factor)

Question 14

If our statistics tell us there is a relationship between our exposure and outcome

Answer 14

We have to figure out if the association is causal.

Question 15

What is neither necessary nor sufficient?

Answer 15

The most complex of all the models but it most accurately represents causal relationships.

Question 16

Which type of causal relationships rarely occurs?

Answer 16

Necessary and sufficient.

Question 17

Which type of causal relationships is the most complex?

Answer 17

Neither necessary not sufficient.

Question 18

Temporal relationship

Answer 18

The outcome must occur after the exposure (exposure before disease)
Length of the interval between exposure and disease occurrence.

Question 19

Strength of association

Answer 19

The statistical association between exposure and an outcome.

Question 20

Dose-response relationshiop

Answer 20

The dose of an exposure increases, the risk of disease also increases.

Question 21

Replication of the findings

Answer 21

If a relationship is causal, we should find it consistently in different studies and different populations.

Question 22

Biologic plausibility

Answer 22

The association and relationship observed should be biologically possible. (Back up by biologic knowledge)

Question 23

Consideration of alternate explanations

Answer 23

Investigators should examine potential confounding and external factors to figure out if the observed association could be mediated and explain away by any of those factors.

Question 24

Cessation of exposure

Answer 24

If a factor is associated with an outcome, then disease incidence and prevalence should decline if we eliminate the factor.

Question 25

Consistency with other knowledge

Answer 25

If a relationship is causal, then we should see the association between factors and outcomes in existing research.

Question 26

Specificity of the association

Answer 26

An association is specific when a certain exposure is associated with only one disease.