12. Type II error occurs when an individual fails to reject H₀ when H₀ is false.

True or False

13. A clinical trial was conducted comparing a new compound designed to improve wound healing in trauma patients to a placebo. After treatment for 5 days, 60% of the patients taking the new compound had a substantial reduction in the size of their wound as compared to 44% in the placebo group. The number of subjects would be required to detect the difference in proportions observed in the trial with 80% power at = 0.05 in a two sided test is 154 in each group.

True or False

14. The sample correlation coefficient is equal to the covariance of x and y divided by the square root of the product of s_x² times s_y².

True or False

15. Choosing the alpha level for a hypothesis test allows researchers to control the probability of committing a type II error.

True or False

16. A clinical trial is conducted on a specific drug used to treat severe migraines and it is noted that approximately 25% of individuals in the study fail to respond to the drug and the medication appears to give them severe episodes of nausea and vomiting. Upon further examination it is revealed that these individuals carry a genetic marker, and the individuals who did not experience the side effects of nausea and vomiting did not have the same marker as those individuals who experienced the side effects. This is an example of which of the following?

Group of answer choices

A. Confounding

B. Effect modification

C. Selection bias

D. Differential bias