12.32 Placebo helps cholesterol? A clinical trial admits subjects suffering from high cholesterol, who are then randomly assigned to take a drug or a placebo for a 12-week study.

For the population, without taking any drug, the correlation between the cholesterol readings at times 12 weeks apart is 0.70. The mean cholesterol reading at any given time is 200, with the same standard deviation at each time.

Consider all the subjects with a cholesterol level of 300 at the start of the study, who take placebo.

a. What would you predict for their mean cholesterol level at the end of the study?

b. Does this suggest that placebo is effective for treating high cholesterol? Explain.