中国大学MOOC: 设http://img2.ph.126.net/4C035zJDwrzMT_J9FmYiDg==/6630868754095094843.png和http://img2.ph.126.net/XAru866oLG0sEHOiLQKuew==/6630063911583248051.png都是http://img1.ph.126.net/gfBNNFJjL6jdtshQimeoUw==/3250473031155123904.png的无偏估计量，且http://img0.ph.126.net/c4Nd5WEAzQdYR8zQs1pGeA==/6632735724840530529.png,则称http://img2.ph.126.net/4C035zJDwrzMT_J9FmYiDg==/6630868754095094843.png比http://img2.ph.126.net/XAru866oLG0sEHOiLQKuew==/6630063911583248051.png更有效，或http://img2.ph.126.net/4C035zJDwrzMT_J9FmYiDg==/6630868754095094843.png比http:/
举一反三
- <img src="http://img1.ph.126.net/xRWXQUfZJwmSXkQiZ0l2HQ==/3826089358528721080.jpg" />? <img src="http://img2.ph.126.net/QX-jBzzFTrwpTjQkcBtfcg==/2449958197307439176.jpg" />|<img src="http://img0.ph.126.net/3XApesgU0Iga8L5Tkm0YXg==/6630324495838409649.jpg" />|<img src="http://img2.ph.126.net/sPsiWYSStdIbrCUcsMBK9A==/3114802092298176869.jpg" />|<img src="http://img1.ph.126.net/y-FdOVmaocQvOIOXtXTxEw==/662592095194801258.jpg" />
- <img src="http://img2.ph.126.net/qowvyGJmU71A6UIpMtWkYw==/6619531689700953755.jpg" />? <img src="http://img2.ph.126.net/un3GDHXLxtcRiMEcP1z7yg==/6619072093840546265.jpg" />|<img src="http://img2.ph.126.net/IZ9fF3KQHcgJNZoygylhHQ==/6630845664350440712.jpg" />|<img src="http://img2.ph.126.net/_iw_TRTbgBcFfQ9EIzN3YA==/6619139164049839979.jpg" />|<img src="http://img2.ph.126.net/Tehi0XAX-FVa8la7PAFlnw==/2435602973495420798.jpg" />
- <img src="http://img1.ph.126.net/JMg9tqo6gf8sEot0y9NSUg==/6619559177490984445.gif" />? 0|<img src="http://img1.ph.126.net/uSXYTJKY1--cmM46BmL7Pg==/1177972777551495010.gif" />|<img src="http://img0.ph.126.net/-vDBDVZEQJqbFun7PrX7vg==/2887370311115280318.gif" />|<img src="http://img2.ph.126.net/NK1mnxUZa_ibCGqQvHOaoQ==/2435884448470832003.gif" />
- 设总体X～N(μ,σ^2),μ和σ是未知参数。为估计参数σ^2的置信区间，应选T=____________作为枢轴变量,并且T服从______。? <img src="http://img2.ph.126.net/SHUrsWncVzw3TbqMT630Ug==/6632510324955921443.png" /><br />|<img src="http://img2.ph.126.net/I5VmIURcDfhDZIPIQy5JZw==/6632334403095483329.png" />|<img src="http://img0.ph.126.net/v1kDLV9rE4i9IWRPugufXQ==/6632404771839652521.png" />|<img src="http://img0.ph.126.net/sQOy3VhGtuk-bcM7dsC3kQ==/6632272830444326010.png" />
- <img src="http://img0.ph.126.net/q6tqn77YyTg_j7CabeHYJw==/3109735542717391842.jpg" />? <img src="http://img1.ph.126.net/QO3FWMGgxAVtN31l0ulKFw==/6619487709235793443.jpg" />|<img src="http://img2.ph.126.net/-x9WCwFJKaqmfOJLJjH0_Q==/6630623563001319953.jpg" />|<img src="http://img1.ph.126.net/5eiGUQZYA2gEX9q4m57n4Q==/6608642126539334311.jpg" />|<img src="http://img1.ph.126.net/YixVkAU6iexb7xitW-q8Lg==/6630125484233816848.jpg" />