Question

22 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 = 28 college students. Each student is given a ginkgo biloba supplement daily for 6 weeks and then all of the participants are given a standardized memory test Scores on the standardized test are = 80 and standard deviation of 15 The sample of 28 students had a mean score of M = 85. (8 points) a) Do the data indicate a significant effect of the herb on memory? Use a two-tiled lost with a 0.05 (Show all steps ) b) Compute Cohen's d to measure the size of the effect if it exists c) Write a sentence describing the outcome of the hypothesis test as it would appear in a research report

Answer 1

a)

n: sample size

X bar: sample mean

sigma: standard deviation of population.

n=28 M=80 x= 85 Ho: M=80 (we want to know if it differs from this value when gingko biloba Hi Ho MF80 is administered) 8=85 n = 28 0:15 Two tailed test 2=51 ~ ZNN(0,1) 2X-M N NOOD olin MES 2.5% 7score for the sample 70.000 20.025 = 1.96 Fokus e is zo g jelds - 85-80 orn 115/178 > z= roscat 1.76

nus, < 20025 1.1.7641.96) z does not die in onjection region =) Ho is not regered

b) Since this test does not consider two independent groups of study, Cohen's d test is inapplicable.

c) Since the null hypothesis H0 cannot be rejected, there is insufficient evidence from the sample experimented that gengko bilboa has an effect on the human memory at a significance level of 5%.