① 对于任意的常数<imgwidth="179"height="22"v:shapes="_x0000_i1205"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image274.png">是<imgwidth="12"height="18"v:shapes="_x0000_i1206"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image276.png">的无偏估计,且<imgwidth="73"height="42"v:shapes="_x0000_i1207"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image278.png">,<imgwidth="73"height="42"v:shapes="_x0000_i1208"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image280.png">,<imgwidth="32"height="20"v:shapes="_x0000_i1209"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image282.png">达到最小
② 对于任意的常数<imgwidth="179"height="22"v:shapes="_x0000_i1210"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image274.png">是<imgwidth="12"height="18"v:shapes="_x0000_i1211"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image276.png">的无偏估计,且<imgwidth="73"height="42"v:shapes="_x0000_i1212"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image278.png">,<imgwidth="73"height="42"v:shapes="_x0000_i1213"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image280.png">,<imgwidth="32"height="20"v:shapes="_x0000_i1214"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image282.png">达到最小
③ 对于任意常数<imgwidth="95"height="29"v:shapes="_x0000_i1215"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image284.png">,<imgwidth="202"height="26"v:shapes="_x0000_i1216"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image286.png">都是<imgwidth="12"height="18"v:shapes="_x0000_i1217"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image276.png">的无偏估计,并且当<imgwidth="46"height="40"v:shapes="_x0000_i1218"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image288.png">时,<imgwidth="35"height="20"v:shapes="_x0000_i1219"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image290.png">达到最小