At a prospective experiment, based on a power calculation, event incidence of 10% vs 20%, 80% power, and  p= 0.05, therefore, estimated that a sample size of 500 subjects would be sufficient to investigate the relationship between independent factor and the dependent factor.

请问:样本量500是怎样根据power calculation算出来?

[此贴子已经被作者于2008-12-6 6:38:30编辑过]