临床试验样本含量问题

　　临床试验样本含量问题。在读其他文章时经常读到
103 events were needed for the study to have a power of 80% to confirm the surperiority of *** over *** with the use of a log-rank test and a two-sided significance level of 5%. Setting the duration of enrollment to 1 years with a minimum follow-up period of 24 months, and a 10% dropout rate, we planned to enroll 152 patients.

请教各位前辈，103 events 是如何计算出来的，152是如何算出来的？还有招收入组和随访时间是否影响样本含量？
===有问必答===
30金都没人回复。我在发的帖子就没有被回复过，伤心了。以后不来了。