单样本率分析时，如何用SAS进行样本含量计算？

我要计算一种药物治疗的效果，单一样本，如何根据治疗有效率计算样本含量？
一篇论文中这样的结果是怎么算出来的？
“using an estimate that 60% of patients would achieve a≥50% improvement in PANSS total score after 12 weeks, enrolment of300 patients would provide a 95% confidence interval of 53.64% to 66.12%,accounting for a 16% dropout rateAll statistical analyses and treatment effectswere tested at a two-sided significance level of 0.05. Statistical AnalyticSystem software version 9.2 (SAS Institute, Cary, North Carolina, USA) was usedto perform all statistical analyses.”