A major advantage of cohort studies over case-control studies with respect to the role of a suspected factor in the etiology of
a disease is that: a. they take less time and are less costly.
b. they can utilize a more representative population.
c. it is easier to obtain controls that are not exposed to the suspected factor.
d. they permit direct estimation of risk of disease in those exposed to the suspected factor.
e. they can be done on a double-blind basis.
d. they permit direct estimation of risk of disease in those exposed to the suspected factor.
Explanation:
A major advantage of cohort studies over case-control studies with respect to the role of a suspected factor in the etiology of a disease is that they permit direct estimation of risk of disease in those exposed to the suspected factor.
Since West Nile virus was discovered in the United States in 1999, the virus has been detected in over 300 species of dead birds. Although some infected birds, especially crows and jays, frequently die of infection, most birds survive.
