70. 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 in the next column is some computer output from a two-sample t-test computed for the data.

2-Sample t-Test of mG - mP 7 0 Difference Between Means = -0.9914 t-Statistic = -1.540 w>196 df P = 0.9374

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.

10 10 Memory 5 -5 -10 Ginkgo Placebo Treatment