1. G Dear ©2010 – Not to be sold/Free to use
Stage 4
Year 9
Data Analysis
Standard Deviation
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G Dear ©2010 – Not to be sold/Free to use

2. Standard Deviation Formula (1/2)
(Measures the spread of scores)
 means standard deviation.
x means each individual score.
x means the mean.
n means the number of scores.
End of
Slide

3. Standard Deviation Formula – Example (2/2)
Find the Standard Deviation for the scores
12, 12, 15, 17, 19
Score 12 15 17 19
x-x
(x-x)2
x = 5
12-15 -3
(-3)2 9 75 5 =
= 15
12-15 -3
(-3)2 9
15-15
(0)2
17-15 +2
(+2)2 4
19-15 +4
(+4)2 16
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Slide
Σ(x-x)2= 38
Now do it on your calculator 3