1. Questions

2. Practice Question 1
An epidemiologic investigation began on January 1, 2012 , identified a population of 2,000 individuals among whom 22 were found to have avian influenza. During the year of study, 11 new additional cases were found and among the total cases there were 8 deaths.
What is the point prevalence on January 1, 2012?
22/2,000
11/2,000
33/2,000

3. Practice Question 2
An epidemiologic investigation began on January 1, 2012 , identified a population of 2,000 individuals among whom 22 were found to have avian influenza. During the year of study, 11 new additional cases were found and among the total cases there were 8 deaths.
What is the incidence rate?
22/2000
33/2000
11/2000
11/1978
3/1978

4. Practice Question 3
An epidemiologic investigation began on January 1, 2012 , identified a population of 2,000 individuals among whom 22 were found to have avian influenza. During the year of study, 11 new additional cases were found and among the total cases there were 8 deaths.
What is the mortality rate?
8/11
8/2000
8/1992
11/1978
8/33

5. Practice Question 4
An epidemiologic investigation began on January 1, 2012 , identified a population of 2,000 individuals among whom 22 were found to have avian influenza. During the year of study, 11 new additional cases were found and among the total cases there were 8 deaths.
What is the case fatality rate?
8/11
8/2000
8/1992
11/1978
8/33

6. Practice Question 5
To see if hypnosis could reduce chronic pain, investigators randomly assigned 120 volunteers with osteoarthritis to either hypnosis therapy or a control group. Pain levels were checked among the subjects every 3 months during the 12-month study using validated pain measures. Which type of study does this represent?
A. Randomized control trial
B. Community Trial
C. Quasi-experimental

7. Practice Question 6 A. Randomized control trial B. Community Trial
To find out if planting grass on the top of buildings would be effective in reducing air pollution levels in polluted cities, investigators selected two adjacent cities with similar demographic profiles and air pollution levels. The officials of one city agreed to plant grass on all of its public buildings in the downtown area and private buildings where consent was obtained. The other city did not plant any grass. Follow up results were measured after 2 years of growth.
A. Randomized control trial
B. Community Trial
C. Quasi-experimental
Oleckno 2002

8. Practice Problem 7
A cohort study of smoking and bladder cancer was conducted in a small island population. There were a total of 1,000 people on the island. Four hundred were smokers and 600 were not. Fifty of the smokers developed bladder cancer. Fifteen of the non-smokers developed bladder cancer. Calculate and interpret relative risk (RR) A. (50/65) / (585/935) B. (350/400) / (585/400) C. (50/400) / (15/600) D. (50/1000) / (585/1000)
Let’s work through an example.

9. Problem Question 8
Suppose that a case-control study was conducted to evaluate the relationship between artificial sweeteners (AS) and bladder cancer. 3,000 cases and 3,000 controls were enrolled in the study. Among the cases, 1,293 had used artificial sweeteners in the past, while 1,707 had never used artificial sweeteners. Of the controls, 855 had used sweeteners and 2,145 had not. Calculate and interpret odds ratio (OR) A. (1293*1707) / (855*2145) B. (1293*855) / (2145*1707) C. (855*1707)/(1293*2145) D. (1293*2145) / (855*1707)
Let’s work through an example to calculate the OR

10. Practice Question 9
Infants born in Flower Hospital were followed from birth to age 10 starting in 1995 to study the effects of mother’s who used pain killers during pregnancy. What type of study is this?
A. Cross-sectional
B. Ecological
C. Case Control
D. Prospective Cohort
E. Retrospective cohort

11. Practice Question 10
In order to determine if vitamin D is associated with reduced level of ovarian cancer, an epidemiologist identified 10 geographic regions in Sweden and obtain data on annual days of sunlight and ovarian cancer. Regions with more days of sunlight had lower rates of ovarian cancer. What type of study is this?
A. Cross-sectional
B. Ecological
C. Case Control
D. Prospective Cohort
E. Retrospective cohort Oleckno 2002

12. Practice Question 11
A study of 3,000 randomly selected parents were asked whether doctors had ever diagnosed any of their children with asthma or if their child had ever been hospitalized due to asthma. What type of study is this?
A. Cross-sectional
B. Ecological
C. Case Control
D. Prospective Cohort
E. Retrospective cohort

13. Practice Question 12
A study was conducted to determine if alcohol was related colon cancer. Historical data on alcohol use was collected from 400 subjects with colon cancer and 400 subjects without stomach cancer. What type of study is this?
A. Cross-sectional
B. Ecological
C. Case Control
D. Prospective Cohort
E. Retrospective cohort

14. Practice Question 13
Interviews could only be schedule from 10:00am to 2:00pm; working women were less like to participate because they were not available to be interviewed during those time periods.
A. Selection Bias
B. Information Bias
C. Confounding

15. Practice Question 14
Women who wear lip gloss more frequently noted in a previous study to be less likely to report a history of tobacco smoking. Further tobacco smoking increases the risk of lip cancer.
A. Selection Bias
B. Information Bias
C. Confounding

16. Practice Question 15
A case-control study was performed to determine whether head injury was associated with an increased risk of brain tumors in children. The mothers of the children completed a questionnaire that asked them to describe their child’s past history of head injury. The investigators found that the mothers of the children with brain tumor reported a past head injury for 70 of the cases while a past history of head injury was reported for 30 of the controls. What type of Bias was likely to have influenced the results of this study.
A. Selection Bias
B. Recall Bias
C. Confounding
D. Differential referral, diagnostic, surveillance

17. Solutions

18. Practice Question 1 Solution
# of cases of a disease present in the population
at a specified time
# of persons in the population
at that specified time 22
* A
2000

19. Practice Question 2 Solution
# of new cases of a disease during a specified period of time
Total number of people at risk during that period of time 11
*100, D

20. Practice Question 3 Solution
# of all deaths in one year
# persons in the population at midyear 8
* 100, B
2000

21. Practice Question 4 Solution
# of persons dying during a specified period after disease onset or diagnosis
Total # of people with the specified disease 8
* E 33

22. Practice Question 5 Solution
A. Randomized Control Trial

23. Practice Question 6 Solution
B. Community Trial

24. Practice Question 7 Solution
Bladder
Cancer
No Bladder
Totals
Incidence of
Bladder Cancer
Smoke 50
350
400
0.125
No Smoke 15
585
600
0.025
C Relative Risk = Incidence in Exposed = = 5.0
Incidence in Unexposed
Relative Risk = a/(a+b) = 50/ = 5.0
c/(c+d) /600
Interpretation:
Incidence of bladder cancer is 5 times as great in smokers as in non-smokers
Withhold from students

25. Practice Question 8 Solution
Cases
Controls
Exposed to AS
1,293
855
Not Exposed
to AS
1,707
2,145
TOTAL
3,000
D. Odds Ratio = = = 1.90
ad_ bc
(1,293)(2,145)
(855)(1,707)
Interpretation
Odds that a person with bladder cancer used artificial sweeteners was 1.90 times the odds that a person without bladder cancer used artificial sweeteners

26. Practice Question 9 Solution
D. Prospective Cohort

27. Practice Question 10 Solution
B. Ecological

28. Practice Question 11 Solution
A. Cross-sectional

29. Practice Question 12 Solution
C. Case Control

30. Practice Question 13 Solution
A. Selection Bias

31. Practice Question 14 Solution
C. Confounding

32. Practice Question 15 Solution
B. Recall Bias