 The sample size calculation for a classification study is based on precision we want to achieve for sensitivity and specificity. The precision refers to the width of the 95 confidence intervals associated with the estimates. To achieve the 95 confidence interval of plus and minus of 0.16 for 85 sensitivity and 85 specificity, we will need a total sample of 40 subjects. Having a sample size of 40 should achieve statistically significant classification accuracy and clinically meaningful sensitivity and specificity. Accounting a placebo response of 30 and drop out of 10, we need to recruit a total of 61 subjects for the sample of 40. 