Module 9: Confounding & Effect Modification

Question 1

Confounding

Answer 1

The mixing of effects between the exposure, the disease, and a third variable that is termed a confounder

Distorts the relationship between an exposure and disease

Question 2

Effect Measure Modification (Heterogeneity of Effect)

Answer 2

Occurs when the strength of association between an exposure and disease differs according to the level of a third variable, called the effect modifier

Unlike confounding, which is considered a nuisance that epidemiologists want to eliminate, effect measure modification is an interesting phenomenon that epidemiologists aim to describe.

Question 3

Homogeneity of Effect

Answer 3

Occurs when effect modification is not present.

Question 4

Index Year

Answer 4

a cutoff date for controls that is comparable to the diagnosis yer for cases

Question 5

How do epidemiologists determine if a variable is an effect modifier?

Answer 5

in a stratified analysis by comparing the stratum-specific measures of association to one another. If the difference is more than 10%, effect measure modification is present.