Consider the following scenario:

A researcher is interested in determining the effectiveness of a behavioral intervention to lower cholesterol in subjects with cardiovascular disease. Subjects are randomized to either intensive dietary counseling or the usual care. The researcher thinks a difference in 0.1mmol/l in cholesterol levels is clinically meaningful and assumes standard deviation of cholesterol in both groups to be 0.7. She also wants to ensure 90% power and 5% level of significance.

For this writing assignment, you will be responding to the following questions and prompts, and then explaining your answers. Include references for your statements in APA format.

• What is the primary endpoint?

• What was the expected effect size (size of difference)?

• Explain the meaning of 5% significance level and power in common terms.

• Identify the sample size formula to be used and use G*Power to calculate the required sample size.

• If the calculated sample size is too large to be feasible, the researcher is prepared to change the power to 80%. Calculate the sample size at 80% and compare it to the original sample size.