作者somebody01 (休养中....)
看板Statistics
标题[问题] 样本数的问题
时间Tue Feb 10 20:04:39 2009
Example
Suppose that a city of N = 100,000 citizens is interested in
assessing the support for a new policy of waste recycling. To estimate
the proportion p in favor of new policy, how large a simple is require
so that with 95% confidence the maximum error of the estimate of p
is 0.03?
解答上是 ╴╴╴╴╴╴╴╴╴╴╴
∕100000 - n 0.5×0.5
0.03 = 1.96×∕ ————— × ————
√ 100000 - 1 n
解得 n = 1055.85 取 n = 1056
我的疑问是为什麽不是代公式解就好，以p = 0.5求解。
前面要多那一项? 因为要校正??
拜托板上的高手为我解惑 感谢不尽
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1F：推 uramf:因为要校正?? 因为要校正。 02/10 20:18
2F：→ somebody01:u大可以告诉我如何判断是否需要校正吗? 02/10 21:16
3F：→ moniya:题目有给大N(有限母体)，此时就要用校正系数。 02/10 22:06
4F：→ somebody01:了解 感谢两位高手的解答 02/10 22:47