2009-12-809-10学年第一学期研究生课程112009-12-809-10学年第一学期研究生课程126练习1?We?would?like?to?start?an?Internet?Service?Provider?(ISP)?and?need?to?estimate?the?average?Internet?usage?of?households?in?one?week?for?our?business?plan?and?model.?How?many?households?must?werandomly?selectto?be?95%sure?that?the?sample?mean?is?within?1?minuteof?the?population?meanμ.?Assume?that?a?previous?survey?of?household?usage?has?shownσ=?6.95?minutes.2009-12-809-10学年第一学期研究生课程137学会阅读帮助自学2009-12-809-10学年第一学期研究生课程15阅读帮助文件，理解各个参数的含义?Underlying?data?distribution?Finite?Population?Size?Confidence?Coefficient?Precision?Know?Standard?Deviation2009-12-809-10学年第一学期研究生课程168Know?Standard?Deviation?PASS2009-12-809-10学年第一学期研究生课程17Know?Standard?Deviation?If?your?sample?sizeis?greater?than?30,?you?can?replaceσ(population?standard?deviation)by?the?s(sample?standard?deviation).?If?your?sample?size?is?less?than?or?equal?to?30,?the?population?must?be?normally?distributed?and?you?must?know?the?σin?order?to?use?the?formula?on?the?normal?distributiondistribution.?An?alternate?solution?method?is?to?use?the?Student?t?Distribution?developed?by?William?Gosset.(Source: http://www.isixsigma.com/library/content/c000709a.asp)2009-12-809-10学年第一学期研究生课程189Know?Standard?Deviation?样本量大时：勾或不勾差不多?样本量小时：?σ已知，勾?σ未知，以s替代，不勾2009-12-809-10学年第一学期研究生课程19练习2?分析不同参数的变化对样本量大小的影响–标准差–容许误差请把两个参数画在一张图上–αPrecision50?100?150?200?250或50?to?250?by?502009-12-809-10学年第一学期研究生课程2010
模型设计样本量评估
