Owner's manual

Page 8-20
To calculate this last result, we can use the following:
The standard deviation of the grouped data is the square root of the variance:
N
ssw
w
ssw
V
n
k
kk
n
k
k
n
k
kk
∑
∑
∑
=
=
=
−⋅
=
−⋅
=
1
2
1
1
2
)()(