Measures of dispersion

1
Measures of dispersion

• Standard deviation (from the mean)

ready
2
Data 2 3 7
0
2
4
6
8
2 3 73
Mean
4
ready
3
Data 2 3 7
Deviation from mean
0
2
4
6
8
-1
-2
3
ready
4
Data 2 3 7
Mean deviation from mean
0
2
4
6
8
-1
-2
3
(-2)
(-1)


0
3
3
Always 0 - Not very useful !
ready
5
Data 2 3 7
Deviation
0
2
4
6
8
-1
-2
3
(-2)
(-1)
3
ready
6
Data 2 3 7
Square of deviation
0
2
4
6
8
-1
2
2
2
-2
3
(-2)
(-1)
3
ready
7
Data 2 3 7
Square of deviation
0
2
4
6
8
-1
1
2
2
2
-2
3
(-2)
(-1)
4
3
9
ready
8
Data 2 3 7
Mean square of deviation
0
2
4
6
8
-1
1
2
2
2
-2
3
(-2)
(-1)


14 3

4
3
3
3
9
2
S
d
n
14 3
Mean square of deviation
ready
9
Data 2 3 7
Root of mean square of deviation
0
2
4
6
8
-1
1
2
2
2
-2
3
(-2)
(-1)


2.2
4
3
3
3
9
2
S
d
2.2
n
14 3
Mean square of deviation
ready
10
Data 2 3 7
Root of mean square of deviation
0
2
4
6
8
-1
1
2
2
2
-2
3
(-2)
(-1)


2.2
4
3
3
3
9
2
S
d
2.2
standard deviation
n
14 3
Mean square of deviation
ready