1. Question: If the incidence rate of a very serious disease is 25/100,000 person-years and the prevalence of this disease in the population is 75/100,000, what is the average survival time of individuals who contract this disease?
2. Question: A report of a clinical trial of a new drug versus a p...
1. Question: If the incidence rate of a very serious disease is 25/100,000 person-years and the prevalence of
this disease in the population is 75/100,000, what is the average survival time of individuals who contract
this disease?
2. Question: A report of a clinical trial of a new drug versus a placebo noted that the new drug gave a
higher proportion of successes than did the placebo (70% versus 40%). The report ended with the
statement that the p value associated with this finding was equal to 0.05. This means that 5 out of 100
patients did not benefit from the new drug.
3. Question: When a new prevention measure for a disease is developed, both the incidence and prevalence
of the disease will decrease over the long term.
4. Question: What can randomization do that no other method to control confounding can do?
5. Question: If an exposure has no association with an outcome, then the attributable proportion in the
exposed is 1
6. Question: 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…
7. Question: Consider the situation in a cohort study where the crude risk ratio is 2.5. The data are then
divided into two groups. In the first group the group-specific risk ratio is 1.0, and the second group’s risk
ratio is 4.0. Which of the following is present?
8. Question: If an exposure has no association with an outcome, then the odds ratio will be 1.
9. Question: Suppose that a study on obesity and cancer contained the following statement:
Many epidemiological studies conducted in the U.S. and abroad have also found that a high body mass
index increases the risk of cancer mortality. Which one of Hill’s guidelines for assessing causation is
supported by this statement?
10. Question: 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 ratio calculated
from this study?
11. Question: In January, 2001 forty heterosexual hemophiliac patients (all males) were asked to participate
in a 3 year prospective study . The men were to undergo an interview, physical examination, and blood
testing for HIV status every 6 months for 3 years. Among the 40 subjects there were 30 who were
seronegative and healthy for the entire duration of the study, and all of these were followed for the entire
3 years. During the initial screening, 2 of the men were found to already be HIV+, although none of them
had clinical signs of AIDS. The table below describes the 10 subjects who either tested HIV positive, or
became lost to follow-up, or already were HIV positive at the start of the study.
12. Question: Use your knowledge of the sufficient-component causal model to choose the best answer to
complete this sentence:
Blocking the action of a cause will prevent all cases of disease by all causal
mechanisms.
13. Question: 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. What measure of association should be calculated to determine the
strength of the relationship between aspirin and colon cancer?
14. Question: In January, 2001 forty heterosexual hemophiliac patients (all males) were asked to participate
in a 3 year prospective study . The men were to undergo an interview, physical examination, and blood
testing for HIV status every 6 months for 3 years. Among the 40 subjects there were 30 who were
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