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 thi
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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 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.
15.Question: Information bias occurs.
16.Question: Which of the following depends on the rate at which new cases develop as well as the duration that the cases have the disease?
17.Question: 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 person’s 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:
18.Question: 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 person’s 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. What type of study is this?
19.Question: Cigarette smoking is a of lung cancer.
20.Question: Suppose that your company has just developed a new screening test for a disease and you are in charge of testing its validity and feasibility. You decide to evaluate the test on 1000 individuals and compare the results of the new test to the gold standard. You know the prevalence of disease in your population is 30%. The screening test gave a positive result for 292 individuals. 285 of these individuals actually had the disease on the basis of the gold standard determination. Calculate the predictive value of a positive test:
21.Question: Which measure of disease frequency best describes the following: the percentage of nursing home residents who have bed sores on July 1, 2012.
22.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 the population risk difference calculated from this study?
23.Question: A randomized experimental study was conducted to evaluate the effectiveness of a new pertussis vaccine. One thousand healthy children were randomized to receive either the new vaccine (500 children) or the old vaccine (500 children). The children were followed for two years to monitor the incidence of pertussis. At the end of the study, the risk ratio for developing pertussis was 0.5 among the children who received the new vaccine compared to children who received the old vaccine. The 95% confidence interval for this relative risk was 0.2-0.8 and the p value was 0.01. State in words your interpretation of the risk ratio.
24.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 difference calculated from this study?
25.Question: Which measure of association is commonly used by public health officials to determine which exposures are most important to the entire population and helps prioritize prevention activities?
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