1.Question: Suppose that an experimental study investigator randomized 100 men to the treatment group and 100 men to the comparison group. However, only 75 men in the treatment group and 85 men in the comparison group were able to comply exactly with their assigned regimens. Should the data analysis be based on the 200 men originally randomized or the 160 men who were able to comply? Choose the best answer.

2.Question: What type of observational study design is best suited to study a disease that has a long latent and induction period?

3.Question: Length bias occurs because fast growing tumors are more likely to be picked up by a screening test than are slow growing tumors.

4.Question: Cigarette smoking is a of lung cancer.

5.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 ratio (a.k.a. relative risk) using the given data. The numeric value of the risk ratio is…

6.Question: Adherence to which ethical principle helps determine whether the burdens and benefits of research are distributed fairly?

7.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?

8.Question: Which type of measure of disease frequency best describes the following: the percentage of healthy, at-risk children in a daycare who develop impetigo (a skin disease) during March 2012.

9.Question: What would happen to the predictive value positive if a screening test were administered in a population with a disease prevalence of 1% instead of 30%? (Assume that the sensitivity and specificity of the test remain the same.)

10.Question: What is the main limitation of a case series?

11.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 sensitivity of the new screening test:

12.Question: The main limitation of which type of study design is that researchers cannot infer the temporal sequence between exposure and disease when the exposure is a changeable characteristic?

13.Question: A case-control study was conducted to identify risk factors for the common cold. Living with children under the age of 10 was one of the risk factors evaluated. The odds ratio for this association was 9.0 and the 95% confidence interval ranged from 1.2 to 85. Which of the following statements is true about this association?

14.Question: The purpose of a control group in a case-control study is to provide an estimate of the exposure distribution in the source population that produced the cases.

15.Question: Which measure of disease frequency best describes the following:

16.Question: Non-compliance in an experimental study biases the results towards the null.

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. Calculate the cumulative incidence of deaths from cancer among the study population over the follow-up period.

18.Question: If an exposure has no association with an outcome, then the odds ratio will be 1.

19.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. The value of the correct measure of association between aspirin and colon cancer is:

20.Question: Suppose that we undertake a cohort study to examine the association of high salt intake and hypertension. Our study population consists of male and female Hispanics and Caucasians. No matching or restriction is performed. Let’s assume that the following facts are true:…… Based on the above information, which of the following are likely confounders in this study?

21.Question: Selection bias is most likely to occur in studies where

22.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:

23.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?

24.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?

25.Question: Suppose that you began a one-year study of tuberculosis (TB) on January 1st, 2013. You enrolled 500 residents in your study and checked on their TB status on a monthly basis. At the start of your study on January 1st, you screened all 500 residents. 30 residents already had existing cases of TB on January 1st. On February 1st, 5 residents developed TB. On April 1st, 5 more residents developed TB. On July 1st, 10 of the residents who had existing TB on January 1st died from their disease. The study ended on December 31, 2010. Assume that once a person gets TB, they have it for the duration of the study, and assume that all remaining residents stayed healthy and were not lost to follow-up. What was the case-fatality rate among residents with TB over the course of the year?