( ) () s. , . , , .
.
.
x1, x2,..., xn ( ), :
x1, x2,..., xn n1, n2,..., nk, n1 + n2 +...+ nk = n ( ),
, , .
, , , , ( , 0).
() - , , .
( variance) . 1918 .
D .
x1, x2,..., xn n , :
x1, x2,..., xn n1, n2,..., nk, n1 + n2 +...+ nk = n,
. 0 , .
( ), ( standard deviation) .
, .
.
Mo , .
Me , , .
(n=2k+1)
Me = xk+1,
(n=2k)
Me = (xk + xk+1)/2.