1. Questions 1 and 2 are based on the following information: You are called to investigate a possible health problem in an office building that may be due to a potential environmental toxin. You arrange with a company that occupies two levels of the building to follow all 300 office employees for 30 days. Every day the employees report their health status. Nothing happens until day 10, when 35 employees report of respiratory distress. On day 20, 70 employees report of respiratory distress. The remaining employees do not report any problems over the 30 day period. What is the incidence rate of respiratory distress in this study population? a. 1.4 per 100 person-days b. 2.1 per 100 person-days c. 2.8 per 100 person-days d. 1.0 per 100 person-days 1 point 2. What is the cumulative incidence of respiratory distress over a 30-day period? a. 35% b. 65% c. 11.6 per 100 person-days d. 35 per 100 person-days 1 point 3. Question 3 is based on the following data among women in the United States (US) 3.Based on the information provided, what can you conclude about the crude mortality rate from cervical cancer among women 30-49 years of age in the US? a. The crude mortality rate from cervical cancer among women 30-49 years of age was 1.2 times higher in 1980 than in 2000. b. The crude mortality rate from cervical cancer among women 30-49 years of age was the same in 1980 as it was in 2000. c. The crude mortality rate from cervical cancer among women 30-49 years of age was 1.2 times higher in 2000 than in 1980. d. The crude mortality rate from cervical cancer among women 30-49 years of age cannot be calculated either for 1980 or 2000. 1 point 4. Questions 4 and 5 are based on the following information: Imagine researchers have developed a new rapid screening test for tuberculosis, which they hope will replace the sputum culture (reference standard). To pilot this new test, 1,000 participants were given both test. Rapid test result Sputum culture test result Positive Negative Positive 120 360 Negative 30 490 4. What is the specificity of the new rapid test for detecting tuberculosis (tuberculosis is defined as positive for sputum culture test)? Show your work, and report your answer as a percent rounded to the percent’s tenths decimal place (i.e., to the nearest 0.1%). (If no work is shown, half credit will be deducted from the grading of your response to this question, even if your final answer is correct.)  Enter Answer Your answer will appear here. 1 point 5. If the true prevalence of tuberculosis were to decrease in the above study population, what effect would this have on the positive predictive value of the new rapid test for detecting tuberculosis? a. The positive predictive value would increase. b. The positive predictive value would decrease. c. The positive predictive value would not change. d. The impact on the positive predictive value would depend on the sensitivity. 1 point 6. Which of the following options best represents the term “incubat.

1. 1.
Questions 1 and 2 are based on the following information:
You are called to investigate a possible health problem in an
office building that may be due to a potential environmental
toxin. You arrange with a company that occupies two levels of
the building to follow all 300 office employees for 30 days.
Every day the employees report their health status. Nothing
happens until day 10, when 35 employees report of respiratory
distress. On day 20, 70 employees report of respiratory distress.
The remaining employees do not report any problems over the
30 day period.
What is the incidence rate of respiratory distress in this study
population?
a. 1.4 per 100 person-days
b. 2.1 per 100 person-days
c. 2.8 per 100 person-days
d. 1.0 per 100 person-days
1 point
2.
What is the cumulative incidence of respiratory distress over a
30-day period?
a. 35%
b. 65%
c. 11.6 per 100 person-days
d. 35 per 100 person-days
1 point
3.
Question 3 is based on the following data among women in the
United States (US)
3.Based on the information provided, what can you conclude
about the crude mortality rate from cervical cancer among
women 30-49 years of age in the US?
a. The crude mortality rate from cervical cancer among women

2. 30-49 years of age was 1.2 times higher in 1980 than in 2000.
b. The crude mortality rate from cervical cancer among women
30-49 years of age was the same in 1980 as it was in 2000.
c. The crude mortality rate from cervical cancer among women
30-49 years of age was 1.2 times higher in 2000 than in 1980.
d. The crude mortality rate from cervical cancer among women
30-49 years of age cannot be calculated either for 1980 or 2000.
1 point
4.
Questions 4 and 5 are based on the following information:
Imagine researchers have developed a new rapid screening test
for tuberculosis, which they hope will replace the sputum
culture (reference standard). To pilot this new test, 1,000
participants were given both test.
Rapid test result
Sputum culture test result
Positive
Negative
Positive
120
360
Negative
30
490
4. What is the specificity of the new rapid test for detecting
tuberculosis (tuberculosis is defined as positive for sputum
culture test)? Show your work, and report your answer as a
percent rounded to the percent’s tenths decimal place (i.e., to
the nearest 0.1%). (If no work is shown, half credit will be
deducted from the grading of your response to this question,
even if your final answer is correct.)
Enter Answer
Your answer will appear here.
1 point
5.

3. If the true prevalence of tuberculosis were to decrease in the
above study population, what effect would this have on the
positive predictive value of the new rapid test for detecting
tuberculosis?
a. The positive predictive value would increase.
b. The positive predictive value would decrease.
c. The positive predictive value would not change.
d. The impact on the positive predictive value would depend on
the sensitivity.
1 point
6.
Which of the following options best represents the term
“incubation period”?
a. The period of time from infection in one individual (i.e.,
primary case) to when that individual infects another individual
(i.e., secondary case).
b. The time between when a person can first transmit the
infection and when he/she can no longer transmit the infection.
c. The time from infection by an infectious disease in an
individual to that individual’s first clinical sign or symptom of
the disease.
d. The period between when an individual becomes infected and
when he/she can begin to transmit the disease to others.
1 point
7.
Question 7 is based on the following information:
_________ surveillance: a system by which the public health
authority receives reports submitted from hospitals, clinics, or
other sources for dozens of notifiable diseases, such as rabies.
_________ surveillance is a relatively inexpensive strategy to
cover large areas, and it provides critical information. However,
even though it may be required by law, this surveillance
depends on people in different institutions to provide data, so
data quality and timeliness are difficult to control.
a. Sentinel
b. Passive

4. c. Active
d. Syndromic
1 point
8.
Questions 8 and 9 are based on the following information:
An unusually high number of students presented to the
University Health Clinic with symptoms of gastrointestinal
illness. Many reported having eaten in the dining hall after the
football game on Saturday afternoon. Members of the
Introduction to Epidemiology class were asked to conduct an
investigation.
Six hundred students were identified as having eaten in the
dining hall at 5:00 PM on Saturday. Of these, half the students
reported symptoms of gastrointestinal illness.
The investigators identified potato salad, turkey burgers, shrimp
salad, and cream pie as the foods that were served in the dining
hall at 5:00 PM. All six hundred students who ate then in the
dining hall were interviewed. The table below contains a
summary of the data collected.
Food
Students who ate the food
Students who
did not eat the food
Sick
Well
Sick
Well
Potato salad
150
150
150
150
Turkey burger
220
200

5. 80
100
Shrimp salad
200
60
100
240
Cream pie
75
50
140
60
8. What is the difference in attack rates (i.e., risk difference)
between students who ate the turkey burger and students who
did not eat the turkey burger?
a. -10%
b. 8%
c. 26%
d. 48%
1 point
9.
Which food is the most likely cause of the epidemic?
a. Potato salad
b. Turkey burger
c. Shrimp salad
d. Cream pie
1 point
10.
Questions 10 and 11 are based on additional information:
The student investigators also collected the time of onset of
symptoms for each of the students who were sick:
Day
Time
Number of students who fell ill by end of the hour
Saturday
5:00 PM

6. 0
6:00 PM
20
7:00 PM
30
8:00 PM
20
9:00 PM
40
10:00 PM
30
11:00 PM
50
Sunday
12:00 AM
40
1:00 AM
30
2:00 AM
20
3:00 AM
10
4:00 AM
10
10. What is the median incubation period (in hours) for this
outbreak assuming the exposure occurred at 5:00 PM on

7. Saturday (i.e., hour zero)?
a. 6 hours
b. 7 hours
c. 5 hours
d. 4 hours
1 point
11.
How would you describe this epidemic?
a. Point source epidemic with direct transmission
b. Point source epidemic with indirect transmission
c. Propagated epidemic with direct transmission
d. Propagated epidemic with indirect transmission
1 point
12.
Questions 12 and 13 are based on the following information:
What type of study design is described above?
a. Cross-sectional study
b. Cohort study
c. Case-control study
d. Ecologic study
1 point
13.
Based solely on the information provided, the conclusion that
higher levels of per capita sugar consumption are associated
with higher country-level age-adjusted prostate cancer
incidence is:
a. Correct
b. Incorrect because of failure to distinguish between degrees of
exposure to the outcome of interest
c. Incorrect because of failure to distinguish between disease
incidence and disease prevalence
d. Incorrect because of failure to distinguish between disease
incidence and disease mortality
1 point
14.

8. Which option below best represents the main difference between
cohort studies and clinical trials?
a. The investigator and other study staff are masked in a cohort
study but not in a clinical trial
b. Cohort studies are conducted with humans and clinical trials
are conducted with animals
c. Study investigators control the participant’s exposure in
clinical trial, but not in a cohort study
d. Study investigators follow up participants over time in
clinical trials, but not in cohort studies
1 point
15.
Which of the following statements is FALSE about
randomization and masking in clinical trials? SELECT ALL
THAT APPLY.
a. Randomization is done to conceal treatment assignment.
b. Randomization eliminates bias in the choice of treatment.
c. Masking ensures study groups are comparable at baseline.
d. Masking minimizes bias related to prior knowledge or beliefs
about the treatment for the scientists conducting the study.
1 point
16.
Choose the best study design from the list below for each of the
research questions. Each study design can only be used once.
a. Investigators want to assess the risk of mental health
outcomes from prolonged online video game use among young
adults.
-- Please Select --
b. A pharmaceutical company believes that a drug in
combination with a support program for elder patients will be
more effective than the drug alone.
-- Please Select --
c. A researcher believes that a rare disease in children may be
associated with the use of a common cleaning agent.
-- Please Select --
d. An investigator wants to determine if the prevalence of

9. asthma is higher in men than women.
-- Please Select --
1 point
Questions 17-19 are based on the following information:
An epidemiologist is interested in novel risk factors associated
with incident breast cancer in women, which could be potential
therapeutic targets for future interventions. She proposed a
prospective cohort study design to study these factors in
middle-aged women and requested funding for 15 years of
follow-up. She intends to recruit participants from five primary
care clinics around the United States in 2020.
17.
Which of the following best describes the target population of
this proposed study? Select the ONE best answer.
a. All middle-aged women who have primary care appointments
at the five clinic sites where the study is recruiting in 2020.
b. All middle-aged women in the United States in 2020.
c. All middle-aged women in the United States who do not have
breast cancer in the 21st century and beyond.
d. All middle-aged women in the United States with breast
cancer in the 21st century and beyond.
e. All middle-aged adults in the United States
1 point
18.
Which of the following groups of individuals should certainly
be excluded during screening for enrollment? Select ALL that
apply:
a. Women previously diagnosed with breast cancer, who are
currently in remission.
b. Women never diagnosed with breast cancer who report a
family history of breast cancer
c. Women never diagnosed with breast cancer who report no
family history of breast cancer
d. Women currently receiving chemotherapy for breast cancer
e. Men with a family history of male breast cancer

10. 1 point
19.
The funding agency told the epidemiologist that resources were
limited and requested she design a more efficient study to
answer this research question. What is the best alternative study
design that the epidemiologist should consider?
a. Cross-sectional study of cancer-free women identified at high
risk of breast cancer
b. An ecologic study of neighborhood level overall cancer
prevalence and the prevalence of risk factors from census data
c. A case-control study nested in an existing longitudinal cohort
to compare women with breast cancer to women without breast
cancer
d. A randomized clinical trial of an experimental intervention
that targets the epidemiologist’s hypothesized most important
novel risk factor
e. There are no alternative study designs for this research
question. The prospective cohort study is the only valid way to
answer this research question
1 point
Questions 20 and 21 are based on the information provided
below:
Alzheimer’s Disease is most commonly seen in older adults.
The United States population has a much higher proportion of
older adults compared to the World population.
20.
If the crude incidence rates of Alzheimer’s Disease in the
United States were age standardized to the World population,
what would you conclude regarding the age standardized and
crude rates?
a. The age standardized rate would be the same as the crude
rate.
b. The age standardized rate would be less than the crude rate.
c. The age standardized rate would be greater than the crude
rate.
d. There is no basis for comparison with age standardized rates.

11. e. Age standardized rates are best for public health planning
purposes.
1 point
21.
Which of the following statement(s) is(are) true about the
standardization described above? Select ALL that apply.
a. This is an example of direct standardization.
b. The standard population used is the United States population.
c. If we also standardized the rates of Alzheimer’s Disease
observed in the French population to the World population, then
we could compare the age standardized rates from the United
States to the age standardized rates from France.
d. None of the above are true.
1 point
22.
A small proportion of people who acquire OPAL fever die from
it. The duration of the disease is approximately 2 weeks and for
those who survive it, there is life-long immunity. Which of the
following would result in a decrease in the incidence of OPAL
fever in a given population?
a. Primary prevention
b. Secondary prevention
c. An increase in the case fatality
d. Improving survival from OPAL fever
e. Decreasing the duration of OPAL fever through improved
treatment
1 point
23.
Match the following terms to their corresponding descriptor.
Please note each term may only be used once.
a. Attack rate
-- Please Select --
b. Prevalence
-- Please Select --
c. Incidence rate
-- Please Select --

12. d. Risk difference
-- Please Select --
1 point
24.
Which statement describes how a prospective cohort study is
different from a case-control study?
a. It is an observational study.
b. It is a study design in which a measure of association can be
calculated.
c. It is a form of study design where participants are usually
separated into two different comparison groups.
d. It is a study design that allows one to assess multiple
exposures.
e. It is a study design that allows one to assess multiple
outcomes.
1 point
25.
Which of the following statements is FALSE?
a. Prevalence is a measure of disease burden.
b. Active surveillance tends to be more expensive than passive
surveillance.
c. Endemic disease is defined as the constant presence of a
disease within a specified geographic area.
d. For herd immunity to successfully protect individuals, 100%
of the population must be immunized.
e. All of the above .
Dr. Johnson started a longitudinal study on medication use and
dementia, which recruited 500 patients aged 65 years and older
from 4 clinical sites. Participants provided data on
demographics, lifestyle factors, and medication history at two
time points: baseline and 5-years after baseline. Dementia status
was also assessed at the same two time points via a local
adjudication committee using the Diagnostic and Statistical

13. Manual of Mental Disorders, 4th edition.
1.
Dr. Johnson wants to examine whether prior use of
anticholinergic drugs at age 35 (one of the questions asked at
baseline) is associated with dementia. She identifies
participants with a dementia diagnosis at baseline and selects
age- and sex-matched controls, who are dementia-free at
baseline. What type of study design is she using with the
baseline data? (Check all that apply)
a. Case-control
b. Cohort
c. Randomized controlled trial
d. Ecological
e. Cross-sectional
f. Observational
1 point
2.
Dr. Johnson finds that those with adjudicated dementia
diagnoses at baseline tend to have similar usage of
anticholinergics when compared to counterparts without
dementia. So then, she wants to assess whether current
(baseline) anticholinergic use differed between participants with
dementia at baseline compared to those who did not have
dementia at baseline. What study design is she implementing?
(Check all that apply)
a. Case-control study design
b. Cohort study design
c. Experimental study design
d. Cross-sectional study design
e. Observational study design
1 point
3.
After the study ends, Dr. Johnson provides you access to the
full dataset. Imagine you are interested in characterizing the
degree to which age is associated with future dementia
diagnoses using this dataset. What study design do you use and

14. who do you include in your analysis?
a. Randomized controlled trial, all participants
b. Cohort, all participants
c. Case-control, participants without dementia diagnosis at
baseline
d. Ecological, participants with dementia diagnosis at baseline
e. Cohort, participants without dementia diagnosis at baseline
1 point
4.
Dr. Johnson published a paper investigating the relationship
between exposure to anticholinergic medications at baseline and
dementia incidence. The authors present a(n) __________ of
1.25. What term best fills in the blank?
a. Attributable risk
b. Relative risk (or risk ratio)
c. Risk difference
d. Attack rate
1 point
5.
Which of the following is/are classified as an observational
study (studies)? (select all that apply):
a. Cohort study
b. Case-control study
c. Randomized controlled trial
d. Cross-sectional study
1 point
6.
A research team was interested in maternal geographic
movements in an area with endemic Zika virus. First, they
consulted with a hospital to identify all mothers who gave birth
between 2015 and 2016. They then contacted each mother,
obtained consent to participate in the study, and asked each
mother whether her child was affected by microcephaly. Finally,
they obtained maternal cellphone records for the 12 months
preceding each birth and geocoded the data to describe each
mother’s movements. The paper reported how proximity to

15. known Zika hot zones was associated with an increased risk of
microcephaly.
This study design is best described as (select one best answer):
a. Experimental study
b. Prospective cohort study
c. Retrospective cohort study
d. Case-control study
e. Cross-sectional study
f. Ecological study
1 point
7.
Which of the following statements are NOT true? (select all that
apply)
a. Randomized experimental studies ensure that provider
preference and patient prognosis are not related to whether the
study participant receives the treatment.
b. Cohort studies are the only study design with the ability to
analyze multiple outcomes as they relate to an exposure.
c. When the prevalence of a disease is high, case-control studies
are typically recommended.
d. Matching aims to select controls (free of the disease) that are
comparable to cases (with disease) based on important variables
that are not the exposure of interest in the study.
1 point
8.
An investigator is interested in studying the relationship
between average ambient air pollution in various cities on
community cancer risk within these cities. Which study design
does the investigator have in mind?
a. Prospective cohort study
b. Case-control study
c. Cross-sectional study
d. Ecological study
1 point
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