Question

Vaccine for Malaria ~ In order for a vaccine to be effective, it should reduce a person’s chance of acquiring a disease. Consider a hypothetical vaccine for malaria – a tropical disease that kills between 1.5 and 2.7 million people every year. Suppose this vaccine is tested with 500 volunteers in a village who are malaria free at the beginning of the trial. Two hundred of the volunteers will get the experimental vaccine and the rest will not be vaccinated. Suppose that the chance of contracting malaria is 10% for those who are not vaccinated.

a. Complete the following the table to show the results you’d expect if the vaccine has no effect.

	Contracts Malaria	Does not contract Malaria
Vaccinated
Not Vaccinated

b. Below are the results of this study. Do they suggest the vaccine is effective at reducing the risk of contracting malaria? Provide justification that uses at least two statistical procedures. [Note, this question can be answered in multiple ways. Most correct answers include either a confidence interval, hypothesis test, or both.]

	Contracts Malaria	Does not contract Malaria
Vaccinated	5	195
Not Vaccinated	32	268

c. Continuing from (b), do these results show significant evidence that this experimental vaccine cuts the risk of contracting malaria in half? Conduct a hypothesis test to answer this question – include mention of your observed test statistic, p-value, and estimated effect size.

Answer 1