1. Choose the study design from the following list: Ecological Study, Cross-Sectional Study, Case
Control Study (Case-Based), Nested Case-Control Study, Concurrent Cohort Study, Non-
Concurrent (Historical) Cohort Study, and Experimental Study (RCT)
a. A study assessed the relationship between amount of physical activity and feelings of sadness.
Data was gathered during a one-time interview of students at a high school. The amount of
physical activity and feelings of sadness were determined from interview answers given by the
students. Cross-Sectional Study (1 Point)
b. A study investigated the association between jogging regularly and back problems. At the
start of the study, none of the subjects had back problems. The subjects were divided on the
basis of whether they jogged regularly. During ten years of follow up, the proportion of each
exposure group that developed back problems was determined. Concurrent Cohort Study (1
Point)
c. A study investigating whether used of vitamin C was associated with decreased upper
respiratory infections (URI). The two groups picked for the study were a group 1) who had
reported having an URI in the past two weeks and a group 2) who reported not having had an
URI in the past two weeks. Both groups were asked about how much vitamin C had been used
during the prior two months. Case-Control Study (1 Point)
d. An industrial widget factory had long-term records on employees that recorded the results of
the required annual hearing test. A study was conducted to determine the association of
hearing loss and whether the employees were factory workers or clerical workers. Employee
records, including medical records, were reviewed to select a group of factory workers and
clerical workers. Subjects selected for the study had normal hearing at the start of employment.
Ten year follow up based on review of the records determined the proportion of each group
that developed hearing loss. Non-concurrent Cohort Study (1 Point)
e. A study investigated whether the use of aspirin would decrease the incidence of
cerebrovascular accidents (CVA or stroke). Volunteer subjects were randomly assigned to the
aspirin or usual strike treatment group. Over five years the incidence of stroke was determined
for each group. Experimental Study (1 Point)
f. A study compared two counties for an association of the mean daily concentration of
respirable particles arising from bushfire smoke and the number of hospital emergency room
visits for asthma. Ecological Study (1 Point)
g. Using subjects form a long-term cohort study, a study investigated the association of HDL
cholesterol and congestive heart failure (CHF). Two groups were compared: 1) all subjects who
had developed CHF and 2) a random sample of subjects without heart disease that were
selected during the course of the study. HDL cholesterol was determined from stored blood
samples obtained when subjects started the study. Nested Case Control Study (1 Point)
