A clinical trial compared a candidate for an Parkinson's drug to a placebo and improvement in motor scores after 18 months of treatment. Group (A) received the drug and group (B) received the placebo. A 1.4 1.3 0.9 1.1 1.2 1.4 1.0 1.8 1.4 1.1 1.2 1.0 0.9 1.2 B 0.9 1.0 1.1 0.9 0.9 1.7 1.1 1.4 1.1 1.0 1.0 1.3 1.2 0.8 The mean of group A is 1.21; sd= 0.24 The mean of group B is 1.1; sd= 0.24 a. Does the drug work better than the placebo? Show your working and comment on your answer. [4] b. Give the 95% confidence interval for your best estimate of the true mean of group A and of group B. [2] c. How would your answers for a) and b) change if (all else being equal) both groups comprised 100 subjects? [2] d. The company decides to trail a new drug in 1,000 patients. During the trial five people developed life threatening blood clots. This condition appears in 75 in 100,000 people with the same demographics as the study cohort. Is it safe to continue the drug? [2]