Question

Some researchers claim that herbal supplements like ginseng enhance human memory. To test this claim, a researcher selects a sample of n=30 college students. Each student is given a ginseng supplement daily for six weeks and then all of the participants are given a standard memory test. For the population, scores on the test are normally distributed with μ=80 and σ=20. The sample of n=30 students had a mean memory score of M=85.

a) Are these data sufficient to show that ginseng has a significant effect on memory? Use a two-tailed z-test with an alpha level of α= .05

b) Compute Cohen’s d for this study and interpret the size of the effect

Answer 1