**JAMA**publication: “Effect of Tocilizumab on Disease Activity in Patients with Active Polymyalgia Rheumatica Receiving Glucocorticoid Therapy: A Randomized Clinical Trial”

Sample Size Calculation:

To estimate the required sample size, based on the results of a previous open-label study of tocilizumab in patients with early polymyalgia rheumatica, (10) we selected a 35% between group difference for the primary end point (i.e., achievement of the primary outcome in 25% of the placebo group vs 60% of the tocilizumab group). An improvement of 20% to 40% between

groups is considered clinically important in other rheumatic diseases treated by biologics, such as rheumatoid arthritis (29) or a recent therapeutical trial in polymyalgia rheumatica. (6)

With the 2-sided α risk set at .05, a total of 90 patients (45 in each group) provided 90% power for detecting a 35% difference in the primary end point (ie, a relative risk of 1.4). Assuming that about 10% of patients would not complete the trial, a sample size of 100 participants (50 in each group) was planned.

Q. Find the error in the above Sample Size Calculation paragraph. Note that you do not need to know anything about “power” here.