Standard deviation.
To calculate the standard deviation you
a) Find the mean
b) Find the deviations from the mean
c) Square the deviations from the mean
d) Sum the squared deviations
e) Divide by sum of squares by (N – 1) (this gives you the mean squared error, or the variance)
f) Take the square root to get the standard deviation
|
|
|
Data Values |
Deviations from the mean |
Deviations squared |
|
mean |
4.00 |
1.00 |
3.00 |
9.00 |
|
sum of squares |
28.00 |
2.00 |
2.00 |
4.00 |
|
variance |
4.67 |
3.00 |
1.00 |
1.00 |
|
standard
deviation |
2.16 |
4.00 |
0.00 |
0.00 |
|
|
|
5.00 |
-1.00 |
1.00 |
|
|
|
6.00 |
-2.00 |
4.00 |
|
|
|
7.00 |
-3.00 |
9.00 |