Question

1. A serum cholesterol level above 250 mg/dl of blood is a risk factor for cardiovascular disease in humans.  At a medical center in St. Louis, a study to test the effectiveness of new cholesterol-lowering drug was conducted.  One hundred people with cholesterol levels between 250 mg/dl and 300 mg/dl were available for this study.  Fifty people were assigned at random to each of two treatment groups.  One group received the standard cholesterol-lowering medication and the other group received the new drug.  After taking the drug for three weeks, the 50 subjects who received the standard treatment had a mean decrease in cholesterol level of 10 mg/dl with a standard deviation of 8 mg/dl and the 50 subjects who received the new drug had a mean decrease of 18 mg/dl with a standard deviation of 12 mg/dl.

Does the new drug appear to be more effective than the standard treatment in lowering mean cholesterol level?

1. Write the null and alternative hypotheses to test this claim.

1. Perform a two sample t-test for the difference of two mean.  What is the value of the test statistic?

                    

1. What is the associated P-Value?

1. State your conclusion using .

1. Create a 95% confidence interval for the true mean difference in effectiveness of treatment.

Answer 1