Question

A nutrition store in the mall is selling "Memory Booster," which is a concoction of herbs and minerals that is intended to improve memory performance. To test the effectiveness of the herbal mix, a researcher obtains a sample of n = 16 people and asks each person to take the suggested dosage each day for four weeks. At the end of the four-week period, each individual takes a standardized memory test. The scores from the sample produce a mean of M = 24 with SS = 960. In the general population, the standardized test is known to have a mean of m = 20. Do the sample data support the conclusion that the Memory Booster has a significant effect? Use a two-tailed test with a = .05. Include the null hypothesis in symbols, critical region(s), and a conclusion about significance

Answer 1

Given : Sample size=n=14

Sample mean=M=24

Sample standard deviation=s=

Hypothesized value=m==20

Significance level=

The null and alternative hypothesis is ,

The test is two-tailed test.

Now , df=degrees of freedom=n1=14-1=13

The critical values are ,

; From t-table

The test statistic is ,

Decision : Here , the value of teh test statistic does not lies in the rejection region.

Therefore , fail to reject Ho.

Conclusion : There is not sufficient evidence to conclude that the Memory Booster has a significant effect.