Some researchers claim that herbal supplements such as ginseng or ginkgo biloba enhance human memory. To test this claim, a researcher selects a sample of n = 400 college students. Each student is given a ginkgo biloba supplement daily for six weeks and then all the participants are given a standardized memory test. For the population, it is known that the mean memory score is 70 (and normally distributed) and the standard deviation is 15. The sample of n = 400 students had a mean score of M = 71.5. Use the population standard deviation as the best estimate of the sample standard deviation. Conduct a z-test to see if the mean for the study participants is statistically different (i.e. statistically significant) than the population mean. (1) Show your work, either below or in your scratch work. (2) State your conclusion in a complete sentence. Use the alpha level of p < .05. Do we conclude that there is a difference between the two means?
Some researchers claim that herbal supplements such as ginseng or ginkgo biloba enhance human memory. To test this claim, a researcher selects a sample of n = 400 college students. Each student is given a ginkgo biloba supplement daily for six weeks and then all the participants are given a standardized memory test.
For the population, it is known that the
Conduct a z-test to see if the mean for the study participants is statistically different (i.e. statistically significant) than the population mean.
(1) Show your work, either below or in your scratch work.
(2) State your conclusion in a complete sentence. Use the alpha level of p < .05. Do we conclude that there is a difference between the two means?
1)
Denote μ as the population mean memory score.
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