A study was conducted to investigate the association between exposure to paint fumes and
brain cancer. Employer records from 1960~1980 were used to identify people who worked as
painters and ta second group who did not work as painters. Ontario Cancer registry records
from 1960 to the present were searched for cases of brain cancer in the two groups. This
designs most closely resembles a
① Retrospective cohort study
② Prospective cohort study
③ Ambidirectional cohort study
④ Case-control study
Ans) this is a retrospective study since 1) subject were selected suing employee records form
1960~1980 to classify subjects by exposure and 2) were followed to the present to identify cases
of brain cancer.
Prospective cohort studies are preferable to case-control studies.
① When the exposure of interest is rare
② When the exposure of interest is common
③ When data on past exposure may only be obtained by interview
④ When disease is rare
Which is the best reason to include multiple control groups in a case-control study?
① They measure incidence of disease directly.
② They allow assessments of possible association between exposure and many diseases.
③ They allow investigators to decide beforehand what data to collect.
④ They avoid bias that might occur if measurement of exposure is made after the outcome
of interest is known.
Ans) 3- retrospective cohort studies do not allow investigators the luxury of deciding what data to
collect. They can only choose to form the available data collected at a time before the study
originated. Also, these data which are often collected for other purposes may not have been
collected systematically and in the same way.
The answer ABD are correct for both prospective and retrospective cohort studies.
brain cancer. Employer records from 1960~1980 were used to identify people who worked as
painters and ta second group who did not work as painters. Ontario Cancer registry records
from 1960 to the present were searched for cases of brain cancer in the two groups. This
designs most closely resembles a
① Retrospective cohort study
② Prospective cohort study
③ Ambidirectional cohort study
④ Case-control study
Ans) this is a retrospective study since 1) subject were selected suing employee records form
1960~1980 to classify subjects by exposure and 2) were followed to the present to identify cases
of brain cancer.
Prospective cohort studies are preferable to case-control studies.
① When the exposure of interest is rare
② When the exposure of interest is common
③ When data on past exposure may only be obtained by interview
④ When disease is rare
Which is the best reason to include multiple control groups in a case-control study?
① They measure incidence of disease directly.
② They allow assessments of possible association between exposure and many diseases.
③ They allow investigators to decide beforehand what data to collect.
④ They avoid bias that might occur if measurement of exposure is made after the outcome
of interest is known.
Ans) 3- retrospective cohort studies do not allow investigators the luxury of deciding what data to
collect. They can only choose to form the available data collected at a time before the study
originated. Also, these data which are often collected for other purposes may not have been
collected systematically and in the same way.
The answer ABD are correct for both prospective and retrospective cohort studies.
