QUESTION 1

A case-control study was conducted to evaluate the relationship between aspirin use and the risk of colon cancer. 2,000 cases and 2,000 controls were enrolled in the study. 1,800 of the cases reported using aspirin in the past while 1,200 of the controls reported using aspirin in the past. The value of the correct measure of association between aspirin and colon cancer is:

a.	0.6
b.	6.0
c.	0.2
d.	2.0

5 points

QUESTION 2

A population of 1,000 healthy, at risk people is monitored for one year starting on January 1st and the development of cases of chicken pox is noted. No one has chicken pox at the start of the investigation. Twenty people develop chicken pox on June 30th and forty people develop chicken pox on September 30th. Twenty-four people were lost to follow-up on March 31st and twenty-four people were lost to follow-up on November 30th. None of those lost to follow-up had developed chicken pox prior to becoming lost. Assume that you can get chicken pox only once. What is the cumulative incidence of chicken pox in this population during the one-year period from January 1st through December 31st?

a.	20/1,000
b.	40/1,000
c.	60/1,000
d.	60/108

5 points

QUESTION 3

A study was conducted on the relationship between folic acid supplementation during pregnancy and the risk of having a child with a neural tube defect. The risk ratio comparing supplemented versus non-supplemented women was 0.33. This means that women who take folic acid were 67% less likely to have a child with a neural tube defect.

True

False

5 points

QUESTION 4

A cohort study of coffee drinking and anxiety was conducted at a university campus. There were a total of 30,000 freshmen who participated. 10,000 were coffee drinkers and 20,000 were not. Of the coffee drinkers, 500 developed anxiety during the 4 year follow-up period. Of the non-coffee drinkers, 200 developed anxiety during the same time period. Assume that no one in the population died or was lost during the follow-up period. Which of the following is the correct interpretation of a risk difference calculated from this study?

a.	Coffee drinkers are x times as likely to develop anxiety as compared to non-coffee drinkers.
b.	The excess risk of anxiety among the coffee drinkers is x as compared to non-coffee drinkers.
c.	The excess risk of anxiety among the entire freshmen population is x
d.	None of the above

5 points

QUESTION 5

A study followed 900,000 US adults from 1992 to 2008. At baseline, all participants were screened and determined to be cancer free and their body mass index (BMI) was calculated. Body mass index is a measure of obesity that is calculated using a persons height and weight. Subjects were separated into the following groups according to their BMI: (a) normal weight, (b) slightly overweight, (c) moderately overweight and (d) greatly overweight. 57,145 deaths from cancer occurred in the population during the follow-up period. The following results were seen for men and women when the heaviest members of the cohort were compared to those with normal weight:

Men: Risk ratio of cancer death = 1.5	95% confidence interval = 1.1-2.1
Women: Risk ratio of cancer death = 1.6	95% confidence interval = 1.4-1.9

Which of the following is the correct interpretation of the risk ratio given for the men?

a.	Compared to women, men had a 50% increased risk of cancer death.
b.	Compared to men of normal weight, greatly overweight men had a 50% increased risk of cancer death.
c.	Men who were greatly overweight were 50% less likely to die from cancer than men of normal weight.
d.	None of the above.

5 points

QUESTION 6

The risk difference associated with cigarette smoking is much higher for coronary heart disease than lung cancer. This is because coronary heart disease is a much more common disease than lung cancer.

True

False

5 points

QUESTION 7

Which of the following is an example of incidence rate?

a.	the number of newly diagnosed breast cancer cases diagnosed during 200 person-years of follow-up
b.	the number of men who were found to have high blood pressure at their yearly physical exam
c.	the percentage of infants born with spina bifida (a type of birth defect) among 1,000 liveborn infants

5 points

QUESTION 8

A study followed 900,000 US adults from 1992 to 2008. At baseline, all participants were screened and determined to be cancer free and their body mass index (BMI) was calculated. Body mass index is a measure of obesity that is calculated using a persons height and weight. Subjects were separated into the following groups according to their BMI: (a) normal weight, (b) slightly overweight, (c) moderately overweight and (d) greatly overweight. 57,145 deaths from cancer occurred in the population during the follow-up period. Calculate the cumulative incidence of deaths from cancer among the study population over the follow-up period.

a.	87.5%
b.	6.3%
c.	15.7%
d.	57.1%

5 points

QUESTION 9

What is the main limitation of a case series?

a.	It is difficult to find an adequate exposure group.
b.	There is no explicit comparison group.
c.	It measures effects at the population, not the individual, level.
d.	It is difficult to obtain approval to conduct these studies.

5 points

QUESTION 10

A cohort study of coffee drinking and anxiety was conducted at a university campus. There were a total of 30,000 freshmen who participated. 10,000 were coffee drinkers and 20,000 were not. Of the coffee drinkers, 500 developed anxiety during the 4 year follow-up period. Of the non-coffee drinkers, 200 developed anxiety during the same time period. Assume that no one in the population died or was lost during the follow-up period. Calculate the risk difference using the given data. The numeric value of the risk difference is

a.	6.0 %
b.	4.0 %
c.	5.0 %
d.	None of the above