称<imgwidth="86"height="22"v:shapes="_x0000_i1305"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb10.files/image377.png">是来自总体<imgwidth="14"height="12"v:shapes="_x0000_i1306"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb10.files/image341.png">的一个简单随机样本(简称样本),即<imgwidth="86"height="22"v:shapes="_x0000_i1307"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb10.files/image377.png">满足()
①
<imgwidth="86"height="22"v:shapes="_x0000_i1308"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb10.files/image377.png">相互独立,不一定同分布
②
<imgwidth="86"height="22"v:shapes="_x0000_i1309"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb10.files/image377.png">相互独立同分布,但与总体分布不一定相同
③
<imgwidth="86"height="22"v:shapes="_x0000_i1310"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb10.files/image377.png">相互独立且均与总体同分布
④
<imgwidth="86"height="22"v:shapes="_x0000_i1311"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb10.files/image377.png">与总体同分布,但不一定相互独立