1. Randomization in a clinical trial is defined as which of the following?

A) The process by which individuals are coupled into groups for comparison in order to minimize bias and confounding.

B) The process by which individuals are assigned a number and are selected through the usage of a pattern which minimizes bias and confounding.

C) The process by which individuals are randomly assigned to a treatment or control group which minimizes bias and confounding.

D) The process by which individuals are asked to volunteer for a study which minimizes bias and confounding.

Ahead: Randomized Study Designs

Subject: Chapter 2

2. Assuming 50,000 individuals in the United States are diagnosed every year, and of those individuals diagnosed with HIV each year, approximately 33,500 individuals diagnosed with HIV are gay or bisexual males. What prevalence of the new HIV cases are from members of the population of gay or bisexual males?

A) 0.67%

B) 6.70%

C) 33.0%

D) 67.0%

Ahead: Prevalence

Subject: Chapter 3

3. Ethnicity (i.e., Hispanic versus non-Hispanic) is best described as which type of variable?

A) Dichotomous variable

B) Ordinal variable

C) Categorical variable

D) Continuous variable

Ahead: Ordinal and Categorical Variables

Subject: Chapter 4

4. A clinical trial is being conducted in order to determine the efficacy of a new drug used to treat Rheumatoid arthritis. The efficacy of the medication will not only be determined by the physical improvement of symptoms but also by using a blood test to examine the concentration C-reactive protein (an inflammatory marker) in an individual's blood. If the researcher wants a margin of error for the level of C-reactive protein to be less than or equal to 3.0 mg/dL, and if the standard deviation for C-reactive protein concentrations among arthritis patients was previously documented at 8 mg/dL, how many patients should be recruited for each group in the study assuming a 95% confidence interval will be used to quantify the mean differences between the control group and the treatment group?

A) n for the treatment group = 112; n for the control group = 111

B) n for the treatment group = 56; n for the control group = 57

C) n for the treatment group = 56; n for the control group = 56

D) n for the treatment group = 112; n for the control group = 112

Ahead: Sample Sizes for Two Independent Samples, Continuous Outcome

Subject: Chapter 8

5. A researcher notes that there seems to be a difference in the prevalence of high blood pressure among college-educated individuals who consume low amounts of processed foodsand the prevalence of individuals who only have a high school education and consume high amounts of processed foods. Use the appropriate hypothesis to test for the independence of the two independent variablespresented here at the 5% significance level to ensure confounding has not influenced the study's results. Then, interpret your response.

	Diet Low in Processed Foods
Normal BP	High BP	Total
College Education	124	55	179
High School Education	69	152	221
Total	193	207	400
	Diet High in Processed Foods
Normal BP	High BP	Total
College Education	64	85	149
High School Education	98	153	251
Total	162	238	400

A) The chi square value of 37.724 is higher than the chi square value of 3.84; therefore, we can accept H₀ at the 5% level and reject H₁, which states that level of education and the amount of processed foods in an individual's diet are not independent of one another.

B) The chi square value of 37.724 is higher than the chi square value of 3.84; therefore, we can accept H₀ at the 5% level and reject H₁, which states that level of education and the incidence of high blood pressure are not independent of one another.

C) The chi square value of 37.724 is higher than the chi square value of 3.84; therefore, we can reject H₀ at the 5% level in favor of H₁, which states that level of education and the incidence of high blood pressure are not independent of one another.

D) The chi square value of 37.724 is higher than the chi square value of 3.84; therefore, we can reject H₀ at the 5% level in favor of H₁, which states that level of education and the amount of processed foods in an individual's diet are not independent of one another.

Ahead: Confounding and Effect Modification

Subject: Chapter 9

True/False

6. True or False? Researchers use active-controlled trials to test new medications that are used to treat a particular illness against old medications used to treat the same illness.

Ahead: Randomized Study Design

Subject: Chapter 2

7. True or False? A stratified random sample can be used to ensure underrepresented populations are represented in a study.

Ahead: Probability Sampling: Stratified Sampling

Subject: Chapter 5

8. True or False? It is important for researchers to account for attrition or loss of participants during follow-up.

Ahead: Sample Sizes for Two Independent Samples, Dichotomous Outcome

Subject: Chapter 8

9. True or False? An r value of .8 indicates a strong positive correlation.

Ahead: Introduction to Correlation and Regression Analysis

Subject: Chapter 9

10. True or False? Using a 95% confidence interval to describe an odds ratio and a relative risk ratio allows other researchers to determine if the results were statistically significant because a statistically significant odds ratio confidence interval will not include the number 1.

Ahead: Displaying Associations Among Variables

Subject: Chapter 12

11. True or False? In logistic regression, the predictors are dichotomous, and the outcome is a continuous variable.

Ahead: Introduction to Correlation and Regression Analysis

Subject: Chapter 10

12. True or False? It is more difficult to reject a null hypothesis if we use a 10% level of significance compared with a 5% level of significance.

Ahead: Introduction to Hypothesis Testing

Subject: Chapter 7

13. True or False? The sample size required to detect an effect size of 0.25 is larger than the sample size required to detect an effect size of 0.50 with 80% power and a 5% level of significance.

Ahead: Sample Size for One Sample, Continuous Outcome

Subject: Chapter 8

14. The following are body mass index (BMI) scores measured in 12 patients who are free of diabetes and are participating in a study of risk factors for obesity. Body mass index is measured as the ratio of weight in kilograms to height in meters squared. Generate a 95% confidence interval estimate of the true BMI.

25 27 31 33 26 28 38 41 24 32 35 40

Ahead: Confidence Intervals for One Sample, Continuous Outcome

Subject: Chapter 6

15. The mean body mass index (BMI) in patients free of diabetes was reported as 28.2. An investigator conducting the study hypothesizes that the BMI in patients free of diabetes is higher. Based on the data, is there evidence that the BMI is significantly higher than 28.2? Use a 5% level of significance.

25 27 31 33 26 28 38 41 24 32 35 40

Ahead: Tests with One Sample, Continuous Outcome

Subject: Chapter 7

16. Using the data presented below, a) construct a 95% confidence interval for the mean PEF in children without chronic bronchitis; b) determine how many children would be required to ensure that the margin of error in (a) does not exceed 10 units.

Group	Number of Children	Mean PEF	Std Dev PEF
Chronic Bronchitis	25	281	68
No Chronic Bronchitis	25	319	74