Why US polls always have a margin of error of +/- 3% ?

送交者: 乱劈材于 2005-4-05, 14:32:46:

USA TODAY/CNN/Gallup poll showed the price of gas already is creating financial hardship for 58% of Americans.

This appsume normal approximation of binomial distribution - HunHunSheng (149 bytes) 2005-4-05, 15:30:43
两亿人口抽样一千，Margin of Error 3% - 2Cul4U4 (26 bytes) 2005-4-05, 15:12:44
margin of error = sqrt root of p(1-p)/sample size - HunHunSheng (0 bytes) 2005-4-05, 14:57:50
- 你好像丢了个系数1.96 - 2Cul4U4 (66 bytes) 2005-4-05, 15:16:51
they always have similar sized pool? - chouqilozi (0 bytes) 2005-4-05, 14:49:40
Ordinary Americans should learn from Youths in Sichuan and Shenzhen - HunHunSheng (71 bytes) 2005-4-05, 14:46:09