Question

In a test of the effectiveness of garlic for lowering cholesterol; 64 subjects were treated with raw garlic. Cholesterol levels were measured before and after treatment. The changes (before minus after) in their levels of LDL cholesterol (in mg/dL) have a mean of 0.2 and a SD of 2.36. User a 0.01 significance level to test the claims that with garlic treatment, the mean change in LDL cholesterol is greater than 0. What do the results suggest about the effectiveness of the garlic treatment? Assume that a simple random sample has been selected. Identify the null and alternative hypotheses, test statistics, p-value, and state the final conclusion that addresses the original claim selected.

Answer 1

Given that

mean difference (d-bar) = 0.20

standard deviation Sd = 2.36

sample size n = 64

We have to test whether the mean difference is greater than 0 or not.

test statistic =

degree of freedom = n-1 = 64-1 = 63

using t table with df(63) and test statistic (0.68)

we get

p value = 0.2495

p value is greater than significance level of 0.01, so we failed to reject the null hypothesis

therefore, we can say that there is insufficient evidence to conclude that the mean difference is greater than 0.