Question

Which of the following is an example of an observational cohort study that might be used to
assess the association between agent X and disease Y? (Select one)
a. A group of individuals exposed to agent X are recruited in 1995 and followed until 2004 at
which time they are tested for the presence of disease Y.
b. A group of individuals with disease Y and without disease Y are recruited and interviewed
about exposure to agent X in 2004.
c. A group of individuals exposed to agent X and a group of individuals not exposed to agent X
are recruited and tested for disease Y in 1995.
d. A group of individuals with disease Y and without disease Y are recruited in 2004 and their
past health records screened for documentation of exposure to agent X in 1995
e. A group of individuals without disease Y are recruited in 2004 and their past health records
screened for documentation of exposure to agent X in 1995

Internal validity of an epidemiologic study refers to the extent that… (Select one)
a. The study was conducted with robust methods and findings are not likely due to error, bias,
and/or confounding
b. The findings of the study are able to be confirmed by other investigators using the same
methods
c. The participants in the study are representative of all individuals with the specific outcome of
interest
d. The human subjects completed the informed consent process before data collection
commenced

Answer 1

Q.1. Option E is correct as exposure to any disease like X is not responsible for the disease Y.

Q.2. Option B is correct as the findings of the study are able to be confirmed by other investigators using the same
methods