Epidemiology | Midterm Set 2 Questions and Answers with
100% Correct Answers | Latest Version
Question 1.
Based on data from the Behavior Risk Factor Surveillance System (BRFSS) in Colorado,
between 2013 and 2015, 17.4% of adults aged 18+ reported they were physically inactive.
Which term best describes this measure of occurrence?
Correct Answer: Period Prevalence
Question 2.
Which of the following is the most correct definition of cumulative incidence?
Correct Answer: A proportion composed of the number of new cases occurring
during a specific time interval per total number of people at risk for the outcome
at the beginning of that interval, assuming no losses to follow-up.
Question 3.
You are interested in studying the frequency of falls leading to hospitalization among an
elderly population attending your outpatient clinic. You identify 835 eligible patients over a
4 year period, of whom 215 were followed for 4 years, 331 for 3 years, 104 for 2 years, and
185 for 1 year. During the 4 year period, there were 72 falls requiring hospitalization. What
is the incidence density rate of falls leading to hospitalization per 1,000 person-years in
this population?
Correct Answer: (215*4)+(331*3)+(104*2)+(185 = 2246 72 falls requiring
hospitalization / 2246 person years = 32.05 falls per 1,000 person years
Question 4.
As of January 1, 2012, there were 374 existing cases of Type I diabetes. The most recent
Census reported a population of 294,567 residents living in Boulder on this date. With this
information, what measure of Type 1 diabetes frequency can you calculate?
Correct Answer: Point Prevalence
Question 5.
Calculate the value of the measure of frequency you selected in the previous question, per
100,000 residents.
Correct Answer: (374 cases / 294,567)*100,000 = 127 per 100,000 residents
,Question 6.
It is now January 2014 and as the Boulder County epidemiologist, you want to know the
average annual incidence rate of Type 1 diabetes (T1DM) in the city of Boulder for the
period between January 2012 and January 2014. You have the Boulder County population
size for 2012 and
2013. You also know that there were 374 existing cases with T1DM as of January 2012.
What other information, if any, do you need to calculate the average annual incidence
density rate?
Correct Answer: I can calculate the number of person-years of follow up for my
denominator based on a mid-year population (average of 2012 and 2013) and
the number of years of follow up (2 years), but I need the number of new cases
that were reported between January 2012 and January 2014 for my numerator.
Question 7.
You find out that there were 40 new cases of T1DM reported between January 2012 and
January of 2014. Given this information and the estimated mid-year population of 316,342
Boulder residents, what is the rate of T1DM per 100,000 person-years?
Correct Answer: [40/(2 years*316,342 mid-year population)]*100,000 =
[40/632,684] = 6.3 cases per 100,000 person-years.
Question 8.
Given the total number of cases you now know about as of January 2014, and the new
information that 3 of these patients have died due to diabetes-related complications, what
is the case-fatality of T1DM per 1,000 affected residents in Boulder? Hint: First calculate
the total number of cases as of January 2014.
Correct Answer: (3/414)*1,000 = 7.2 deaths per 1,000
Question 9.
Correct Answer: Period prevalence
Question 10.
The percentage of women with heart disease who died from heart disease over the last 5
years.
Correct Answer: Case fatality proportion
Question 11.
The lifetime risk of breast cancer.
Correct Answer: Cumulative incidence
Question 12.
The number of live-born babies who die of sudden infant death syndrome during the first
year of life per 100,000 baby years of follow-up.
, Correct Answer: incidence density rate
Question 13.
The table below describes the number of skin cancer cases by age-group, within a study
population in which each individual had 100% follow-up for 1 year. What is the total
incidence density of skin cancer in the study population per 100,000 person-years?
Correct Answer: (,000) X 100,000 = 189 per 100,000 person-years
Question 14.
As an epidemiologist at Jefferson County Health Department, you have been tasked with
collecting quantitative data to determine the incidence of Influenza in Jefferson County.
Your supervisor has asked you to develop a sentinel reporting system to collect
quantitative data. Which of following would be the most efficient and accurate efforts to
accomplish this task?
Correct Answer: Establish a network of healthcare clinics, hospitals and
laboratories within Jefferson county to report all individuals with positive
laboratory tests for influenza. In addition, your staff will peri- odically review
laboratory testing results to identify additional missed cases (a combination of
passive and active reporting).
Question 15.
Select the options below that accurately describe some of the distinctions between an
active and passive surveillance system of a health condition.
Correct Answer: Options A and B are correct
A. An active surveillance system is one where public health professionals
actively visit or interacts with health care systems (clinics, laboratories,
hospitals) to ascertain individuals with a particular health condition whereas a
passive system relies upon the healthcare system to report cases to public
health agencies.
B. Active surveillance is more time-consuming and expensive than passive
surveillance.
Question 16.
Why is a cohort design more efficient than a case-con- trol design to study a rare
exposure?
Correct Answer: Subjects can be selected based on their exposure status.
Question 17.
In which scenario would it be best to select a case-con- trol study design over a
retrospective cohort study design?
Correct Answer: The outcome being studied is rare
100% Correct Answers | Latest Version
Question 1.
Based on data from the Behavior Risk Factor Surveillance System (BRFSS) in Colorado,
between 2013 and 2015, 17.4% of adults aged 18+ reported they were physically inactive.
Which term best describes this measure of occurrence?
Correct Answer: Period Prevalence
Question 2.
Which of the following is the most correct definition of cumulative incidence?
Correct Answer: A proportion composed of the number of new cases occurring
during a specific time interval per total number of people at risk for the outcome
at the beginning of that interval, assuming no losses to follow-up.
Question 3.
You are interested in studying the frequency of falls leading to hospitalization among an
elderly population attending your outpatient clinic. You identify 835 eligible patients over a
4 year period, of whom 215 were followed for 4 years, 331 for 3 years, 104 for 2 years, and
185 for 1 year. During the 4 year period, there were 72 falls requiring hospitalization. What
is the incidence density rate of falls leading to hospitalization per 1,000 person-years in
this population?
Correct Answer: (215*4)+(331*3)+(104*2)+(185 = 2246 72 falls requiring
hospitalization / 2246 person years = 32.05 falls per 1,000 person years
Question 4.
As of January 1, 2012, there were 374 existing cases of Type I diabetes. The most recent
Census reported a population of 294,567 residents living in Boulder on this date. With this
information, what measure of Type 1 diabetes frequency can you calculate?
Correct Answer: Point Prevalence
Question 5.
Calculate the value of the measure of frequency you selected in the previous question, per
100,000 residents.
Correct Answer: (374 cases / 294,567)*100,000 = 127 per 100,000 residents
,Question 6.
It is now January 2014 and as the Boulder County epidemiologist, you want to know the
average annual incidence rate of Type 1 diabetes (T1DM) in the city of Boulder for the
period between January 2012 and January 2014. You have the Boulder County population
size for 2012 and
2013. You also know that there were 374 existing cases with T1DM as of January 2012.
What other information, if any, do you need to calculate the average annual incidence
density rate?
Correct Answer: I can calculate the number of person-years of follow up for my
denominator based on a mid-year population (average of 2012 and 2013) and
the number of years of follow up (2 years), but I need the number of new cases
that were reported between January 2012 and January 2014 for my numerator.
Question 7.
You find out that there were 40 new cases of T1DM reported between January 2012 and
January of 2014. Given this information and the estimated mid-year population of 316,342
Boulder residents, what is the rate of T1DM per 100,000 person-years?
Correct Answer: [40/(2 years*316,342 mid-year population)]*100,000 =
[40/632,684] = 6.3 cases per 100,000 person-years.
Question 8.
Given the total number of cases you now know about as of January 2014, and the new
information that 3 of these patients have died due to diabetes-related complications, what
is the case-fatality of T1DM per 1,000 affected residents in Boulder? Hint: First calculate
the total number of cases as of January 2014.
Correct Answer: (3/414)*1,000 = 7.2 deaths per 1,000
Question 9.
Correct Answer: Period prevalence
Question 10.
The percentage of women with heart disease who died from heart disease over the last 5
years.
Correct Answer: Case fatality proportion
Question 11.
The lifetime risk of breast cancer.
Correct Answer: Cumulative incidence
Question 12.
The number of live-born babies who die of sudden infant death syndrome during the first
year of life per 100,000 baby years of follow-up.
, Correct Answer: incidence density rate
Question 13.
The table below describes the number of skin cancer cases by age-group, within a study
population in which each individual had 100% follow-up for 1 year. What is the total
incidence density of skin cancer in the study population per 100,000 person-years?
Correct Answer: (,000) X 100,000 = 189 per 100,000 person-years
Question 14.
As an epidemiologist at Jefferson County Health Department, you have been tasked with
collecting quantitative data to determine the incidence of Influenza in Jefferson County.
Your supervisor has asked you to develop a sentinel reporting system to collect
quantitative data. Which of following would be the most efficient and accurate efforts to
accomplish this task?
Correct Answer: Establish a network of healthcare clinics, hospitals and
laboratories within Jefferson county to report all individuals with positive
laboratory tests for influenza. In addition, your staff will peri- odically review
laboratory testing results to identify additional missed cases (a combination of
passive and active reporting).
Question 15.
Select the options below that accurately describe some of the distinctions between an
active and passive surveillance system of a health condition.
Correct Answer: Options A and B are correct
A. An active surveillance system is one where public health professionals
actively visit or interacts with health care systems (clinics, laboratories,
hospitals) to ascertain individuals with a particular health condition whereas a
passive system relies upon the healthcare system to report cases to public
health agencies.
B. Active surveillance is more time-consuming and expensive than passive
surveillance.
Question 16.
Why is a cohort design more efficient than a case-con- trol design to study a rare
exposure?
Correct Answer: Subjects can be selected based on their exposure status.
Question 17.
In which scenario would it be best to select a case-con- trol study design over a
retrospective cohort study design?
Correct Answer: The outcome being studied is rare
