均值、均方值和方差的估计 √均值 a.=0 √均方值 -ro灿 =m7xo灿 √方差 &-HfIx-4J 云=m7[0-4'd业 1111 均值 0 1 lim ( )d T x T x t t T     均方值 方差 2 2 0 1 lim ( )d T x T x t t T      2 2 0 1 lim ( ) d T x x T xt t T        0 1 ( )d T x xt t T       2 2 0 1 () d T x x x t t T      2 2 0 1 ( )d T x x t t T    均值、均方值和方差的估计