1.NounGiven a random sample
x
1
,
…
,
x
N
{\displaystyle \textstyle \mathbf {x} _{1},\ldots ,\mathbf {x} _{N}}
from an
n
{\displaystyle \textstyle n}
-dimensional random variable
X
{\displaystyle \textstyle \mathbf {X} }
, a mean defined as
"
x
¯
=
1
N
∑
k
=
1
N
x
k
.
{\displaystyle \mathbf {\bar {x}} ={\frac {1}{N}}\sum _{k=1}^{N}\mathbf {x} _{k}.}
"