Multiple Choice

1. A clinical trial is run to assess the efficacy of a new drug to reduce high blood pressure. Patients with a diagnosis of hypertension (high blood pressure) are recruited to participate in the trial and randomized to receive either the new drug or placebo. Participants take the assigned drug for 12 weeks and their blood pressure status is recorded. At the end of the trial, participants are classified as still having hypertension or not. The data are shown here:

Group

Number Randomized

Number of Hypertension at 12 Weeks

Placebo

50

18

New Drug

50

30

What is the prevalence of hypertension at the end of the trial?

a.48%

b.18%

c.30%

d.12%

2. A cohort study is conducted to assess the association between clinical characteristics and the risk of stroke. The study involves n = 1385 participants who are free of stroke at the study start. Each participant is assessed at study start (baseline) and every year thereafter for 5 years. The following data were collected relating hypertensive status measured at baseline to incident stroke over 5 years.

Free of Stroke at 5 Years

Stroke

Baseline: Not Hypertensive

1000

60

Baseline: Hypertensive

300

25

Compute the cumulative incidence of stroke in patients classified as hypertensive at baseline.

a.0.060

b.0.83

c.0.42

d.0.077

3. Which statistical property make odds ratios the ideal measurement for case-control studies?

a.Its insensitivity to confounding factors

b.Its insensitivity to variance

c.Its insensitivity to sampling error

d.Its insensitivity to bias

4. 1,000 people are enrolled in a 10-year cohort study. At the start of the study, 200 have diagnosed CVD. Over the course of the study, 90 people who were free of CVD at baseline develop CVD. What is the cumulative incidence at 10 years?

a.0.09

b.0.45

c.0.1125

d.0.075

5. A clinical trial is run to assess the efficacy of a new drug to reduce high blood pressure. Patients with a diagnosis of hypertension (high blood pressure) are recruited to participate in the trial and randomized to receive either the new drug or placebo. Participants take the assigned drug for 12 weeks and their blood pressure status is recorded. At the end of the trial, participants are classified as still having hypertension or not. The data are shown below. The Estimated relative risk comparing who are free of hypertension at 12 weeks between groups is:

Group

Number Randomized

Number Free of Hypertension at 12 Weeks

Placebo

50

8

New Drug

50

19

a.2.38

b.0.42

c.1.7

d.4.0

True/False

6. True or False? Prevalencerefers to the proportion of participants with a risk factor or disease at a particular point in time.

7. True or False? Cumulative incidence reflects the proportion of participants who become diseased during aspecified observation period.

8. True or False? Relative risk is an ideal form of measurement for a retrospective cohort study design because it allows researchers to recruit both individuals with the outcome of interest and individuals without the outcome of interest, then match individuals from each of the respective groups to individuals of the other group to determine if a specific exposure caused the outcome of interest.

9. True or False? The incidence rate (IR), is computed by taking the ratio of the number of new cases of disease to the total number of person-time units available.

10. True or False? The prevalence of a disease depends on the incidence of the disease as well as the duration of the disease.

Chapter 4

Multiple Choice

1. Marital status is best defined as which of the following types of variables?

a.Dichotomous variable

b.Ordinal variable

c.Categorical variable

d.Continuous variable

2. A study is being conducted to determine the prevalence of lung cancer in a population and the researchers want to note the frequency of each particular stage of cancer among the members of the population who have lung cancer; in this case the stage of cancer is best defined as which of the following types of variables?

a.Dichotomous variable

b.Ordinal variable

c.Categorical variable

d.Continuous variable

3. A study is run to estimate the mean total cholesterol level in children 2 to 6 years of age. A sample of 9 participants is selected and their total cholesterol levels are measured as follows.

180227240197175183195145200

What is the sample mean?

a.193.6

b.180

c.187.5

d.200

4. A study is run to estimate the mean total cholesterol level in children 2 to 6 years of age. A sample of 9 participants is selected and their total cholesterol levels are measured as follows.

180227240197175183195145200

What is the Median?

a.197

b.180

c.227

d.195

5. The following data were collected as part of a study of coffee consumption among graduate students. The following reflect cups per day consumed:

34782103912

What is the 3^rd quartile?

a.8

b.9

c.2.5

d.4

True/False

6. True or False? The standard deviation of any data set is the equivalent of the sample variance of the data set squared.

7. True or False? The best measure of central tendency for a data set containing a high number of single-sided outliers is the mean and the standard deviation.

8. True or False? The median is the best measure of central tendency for a data set where they are no outliers present.

9. True or False? Continuous variables, sometimes called measurement or quantitative variables, take on an unlimited number of distinct responses between a theoretical minimum value and maximum value.

10. True or False? In a study of cardiovascular risk factors, we might collect information on participants such as whether or not they have diabetes, whether or not they smoke, and whether or not they are on treatment for high blood pressure or high cholesterol are examples of ordinal variable?