WGU D401 INTRODUCTION TO EPIDEMIOLOGY
(PA) EXAM TASK 1 QUESTIONS AND CORRECT VERIFIED
ANSWERS WITH RATIONALES 100% GUARANTEED PASS!!
<LATEST VERSION>
1. A county health department notices that emergency department visits for asthma
have increased substantially during the past 6 months. Epidemiologists review the
cases by age, neighborhood, season, and exposure history. Which epidemiologic
question is most directly being addressed by examining these patterns?
A. What is the most effective treatment for asthma?
B. Who is affected, where cases occur, and when they occur
C. Which genetic mutation causes asthma?
D. Which medication should be prescribed for individual patients?
Answer: B
Rationale: Epidemiology examines the distribution and determinants of health-
related events in populations. Describing cases according to person, place, and
time helps identify patterns that may suggest risk factors, environmental
exposures, or transmission pathways. Treatment decisions for individual patients
are clinical rather than primarily epidemiologic.
,2. During an investigation of gastrointestinal illness at a university residence hall,
investigators learn that 48 students became ill after attending a buffet dinner. Of 80
students who ate the chicken salad, 32 developed symptoms. Of 120 students who
did not eat the chicken salad, 12 became ill.
Which finding would provide the strongest initial evidence that the chicken salad
was associated with illness?
A. The total number of ill students was 44
B. More students who did not eat the chicken salad remained healthy
C. The attack rate was higher among students who ate the chicken salad
D. Students who ate the chicken salad were more likely to report nausea
Answer: C
Rationale: An attack rate compares the proportion of individuals who become ill
among those exposed and unexposed during an outbreak. Among those who ate the
chicken salad, the attack rate was 32/80 = 40%. Among those who did not, it was
12/120 = 10%. The substantially higher rate in the exposed group supports an
association between chicken-salad consumption and illness.
3. A public health researcher wants to determine the prevalence of hypertension
among adults living in a city on a specific date. A random sample of residents
undergoes blood-pressure measurements during one month, and researchers record
whether each participant currently has hypertension.
Which study design best fits this objective?
A. Cross-sectional study
B. Retrospective cohort study
C. Case-control study
D. Randomized controlled trial
Answer: A
Rationale: A cross-sectional study measures exposure and/or disease status in a
population at a particular point or period. It is commonly used to estimate
,prevalence. A case-control study begins with disease status, a cohort study begins
with exposure, and a randomized trial assigns an intervention.
4. An epidemiologist is investigating an outbreak of conjunctivitis in two
residential schools. Before comparing possible exposures, the investigator
establishes that a suspected case must include red or irritated eyes beginning
between September 1 and September 14 among students enrolled at either school.
What is the primary purpose of this approach?
A. To identify the pathogen's genetic sequence
B. To create a standardized case definition
C. To calculate the prevalence of conjunctivitis
D. To eliminate confounding variables
Answer: B
Rationale: A case definition establishes consistent criteria for determining who is
counted as a case during an investigation. It commonly incorporates clinical,
person, place, and time characteristics. Standardization prevents different
investigators from counting cases inconsistently.
5. A researcher follows 2,000 factory workers who have no diagnosed hearing
impairment at baseline. One group regularly works in a high-noise area, while the
other works in a low-noise area. Five years later, hearing impairment is measured
in both groups.
Which measure would be most directly appropriate for comparing the occurrence
of new hearing impairment between the two groups?
A. Risk ratio
B. Prevalence ratio only
C. Odds of exposure among cases
D. Case-fatality rate
Answer: A
, Rationale: A risk ratio (relative risk) compares the risk of developing an
outcome in an exposed group with the risk in an unexposed group. Because this
investigation follows disease-free individuals forward to observe new disease, risk
can be calculated directly.
6. An epidemiologist reviews records for 600 patients diagnosed with pancreatic
cancer and selects 600 individuals without pancreatic cancer from the same
population. Previous occupational exposure to certain solvents is then compared
between the two groups.
Which measure of association is most appropriate for this study?
A. Risk ratio
B. Odds ratio
C. Attack rate
D. Incidence rate ratio based only on person-time
Answer: B
Rationale: This is a case-control study because participants are selected based on
disease status and then prior exposure is assessed. The standard measure of
association for case-control studies is the odds ratio (OR).
7. A community health team observes that neighborhoods with the highest air-
pollution levels also have the highest rates of chronic respiratory disease. However,
these neighborhoods also have fewer primary-care clinics and higher rates of
cigarette smoking.
Which concept is most important when interpreting the relationship between air
pollution and respiratory disease?
A. Confounding
B. Randomization
C. Blinding
D. Recall period
Answer: A
(PA) EXAM TASK 1 QUESTIONS AND CORRECT VERIFIED
ANSWERS WITH RATIONALES 100% GUARANTEED PASS!!
<LATEST VERSION>
1. A county health department notices that emergency department visits for asthma
have increased substantially during the past 6 months. Epidemiologists review the
cases by age, neighborhood, season, and exposure history. Which epidemiologic
question is most directly being addressed by examining these patterns?
A. What is the most effective treatment for asthma?
B. Who is affected, where cases occur, and when they occur
C. Which genetic mutation causes asthma?
D. Which medication should be prescribed for individual patients?
Answer: B
Rationale: Epidemiology examines the distribution and determinants of health-
related events in populations. Describing cases according to person, place, and
time helps identify patterns that may suggest risk factors, environmental
exposures, or transmission pathways. Treatment decisions for individual patients
are clinical rather than primarily epidemiologic.
,2. During an investigation of gastrointestinal illness at a university residence hall,
investigators learn that 48 students became ill after attending a buffet dinner. Of 80
students who ate the chicken salad, 32 developed symptoms. Of 120 students who
did not eat the chicken salad, 12 became ill.
Which finding would provide the strongest initial evidence that the chicken salad
was associated with illness?
A. The total number of ill students was 44
B. More students who did not eat the chicken salad remained healthy
C. The attack rate was higher among students who ate the chicken salad
D. Students who ate the chicken salad were more likely to report nausea
Answer: C
Rationale: An attack rate compares the proportion of individuals who become ill
among those exposed and unexposed during an outbreak. Among those who ate the
chicken salad, the attack rate was 32/80 = 40%. Among those who did not, it was
12/120 = 10%. The substantially higher rate in the exposed group supports an
association between chicken-salad consumption and illness.
3. A public health researcher wants to determine the prevalence of hypertension
among adults living in a city on a specific date. A random sample of residents
undergoes blood-pressure measurements during one month, and researchers record
whether each participant currently has hypertension.
Which study design best fits this objective?
A. Cross-sectional study
B. Retrospective cohort study
C. Case-control study
D. Randomized controlled trial
Answer: A
Rationale: A cross-sectional study measures exposure and/or disease status in a
population at a particular point or period. It is commonly used to estimate
,prevalence. A case-control study begins with disease status, a cohort study begins
with exposure, and a randomized trial assigns an intervention.
4. An epidemiologist is investigating an outbreak of conjunctivitis in two
residential schools. Before comparing possible exposures, the investigator
establishes that a suspected case must include red or irritated eyes beginning
between September 1 and September 14 among students enrolled at either school.
What is the primary purpose of this approach?
A. To identify the pathogen's genetic sequence
B. To create a standardized case definition
C. To calculate the prevalence of conjunctivitis
D. To eliminate confounding variables
Answer: B
Rationale: A case definition establishes consistent criteria for determining who is
counted as a case during an investigation. It commonly incorporates clinical,
person, place, and time characteristics. Standardization prevents different
investigators from counting cases inconsistently.
5. A researcher follows 2,000 factory workers who have no diagnosed hearing
impairment at baseline. One group regularly works in a high-noise area, while the
other works in a low-noise area. Five years later, hearing impairment is measured
in both groups.
Which measure would be most directly appropriate for comparing the occurrence
of new hearing impairment between the two groups?
A. Risk ratio
B. Prevalence ratio only
C. Odds of exposure among cases
D. Case-fatality rate
Answer: A
, Rationale: A risk ratio (relative risk) compares the risk of developing an
outcome in an exposed group with the risk in an unexposed group. Because this
investigation follows disease-free individuals forward to observe new disease, risk
can be calculated directly.
6. An epidemiologist reviews records for 600 patients diagnosed with pancreatic
cancer and selects 600 individuals without pancreatic cancer from the same
population. Previous occupational exposure to certain solvents is then compared
between the two groups.
Which measure of association is most appropriate for this study?
A. Risk ratio
B. Odds ratio
C. Attack rate
D. Incidence rate ratio based only on person-time
Answer: B
Rationale: This is a case-control study because participants are selected based on
disease status and then prior exposure is assessed. The standard measure of
association for case-control studies is the odds ratio (OR).
7. A community health team observes that neighborhoods with the highest air-
pollution levels also have the highest rates of chronic respiratory disease. However,
these neighborhoods also have fewer primary-care clinics and higher rates of
cigarette smoking.
Which concept is most important when interpreting the relationship between air
pollution and respiratory disease?
A. Confounding
B. Randomization
C. Blinding
D. Recall period
Answer: A
