Memory. Does ginkgo biloba enhance memory? In an experiment to find out, subjects were assigned randomly to take ginkgo biloba supplements or a placebo. Their memory was tested to see whether it...

Memory. Does ginkgo biloba enhance memory? In an experiment to find out, subjects were assigned randomly to take ginkgo biloba supplements or a placebo. Their memory was tested to see whether it improved. Here are boxplots comparing the two groups and on the next page some computer output from a two-sample t-test computed for the data.

a) Explain in this context what the P-value means.

b) State your conclusion about the effectiveness of ginkgo biloba.

c) Proponents of ginkgo biloba continue to insist that it works. What type of error do they claim your conclusion makes? Explain.