In a densitysampled casecontrol study cases and

by the end of follow­up. In a density­sampled case­control study, cases and controls should be
representative of the person­time contributed by members of the source population, but they do not
need to be representative of everyone with and without the disease respectively (B and C are
incorrect) Likewise, in a cumulative incidence sampled case­control study, cases and controls should
be representative of the people in the source population, but they do not need to be representative of
everyone with and without the disease respectively (B and C are incorrect). Consider, for example, a
scenario in which you are interested in studying breast cancer. You may choose to restrict to female
cases, even though men can develop breast cancer. Enrolling only women is valid, so long as the
source population from which they are drawn consists only of women. D is incorrect because controls
are sampled precisely because they do not have the outcome of interest at the time they are selected
as a control.
1 / 1 pts
Question 7
You are conducting a case­control study investigating whether time of day is associated with the incidence of
bacterial infections as a complication of surgical procedures among patients who underwent an operation
performed at a particular hospital. Would this study involve a primary or secondary study base?
Correct!
Correct!

9/15/2018 Quiz 2 – DAGs / Case-control design: EPI 201: Introduction to Epidemiology: Methods I
9/10
1 / 1 pts
Question 8
Suppose the 4 people listed below are participants in a previously established cohort. You wish to conduct a
case­cohort study using this population. Which subject has the greatest chance of being selected for your
subcohort?

9/15/2018 Quiz 2 – DAGs / Case-control design: EPI 201: Introduction to Epidemiology: Methods I
10/10
Correct!
Correct!
Quiz Score:
8
out of 8