主题：【原创】在医学上什么是证据？送给无知的人们 -- 虽远必诛

盖洛普最近的奥巴马支持率的调查，取1529个18岁以上美国公民，有95%的置信水平，最终结果误差在+-3%

Results are based on telephone interviews with 1,529 national adults, aged 18 and older, conducted Dec. 4-6, 2009, as part of Gallup Daily tracking. For results based on the total sample of national adults, one can say with 95% confidence that the maximum margin of sampling error is ±3 percentage points.

我当年概率也没学好，但是如果总体大到一定程度，同样置信水平和精确度的统计所需的样本数几乎是不再增加的