Standard Deviation in Educational Research

Introduction of Standard Deviation and its use in Educational Research

2. Introduction
Standard Deviation
Example
Formulas
References

3. The standard deviation is the
positive square root of
variance.
It is denoted with S, SD or σ
(sigma).

4. Heights of Dogs in mm

5. Mean =  600 + 470 + 170 + 430 + 300 / 5
Mean =  1970 / 5
Mean = 394 mm

6. So, the Variance is 21,704 &
Standard Deviation: σ = √21,704 = 147.32
= 147 (to the nearest mm)

7. The good thing about the Standard Deviation is that it is useful. Now
we can show which heights are within one Standard Deviation
(147mm) of the Mean:
So, using the Standard Deviation we have a "standard" way of
knowing what is normal, and what is extra large or extra small.
Rottweilers are tall dogs. And Dachshunds are a bit short ...
but don't tell them!

10. Statistics for the Social Sciences, Victoria L. Statistics for the Social Sciences, Victoria L.
Mantzopoulos. Prentice Hall, Englewood Cliffs, NJ. Mantzopoulos. Prentice Hall, Englewood Cliffs, NJ.
1995.1995.
A First Course in Business Statistics 6e James T. A First Course in Business Statistics 6e James T.
McClave and P. George Benson. Prentice Hall, McClave and P. George Benson. Prentice Hall,
Englewood Cliffs, NJ. 1995.Englewood Cliffs, NJ. 1995.
http://www.mathsisfun.com/data/standard-http://www.mathsisfun.com/data/standard-
deviation.htmldeviation.html
http://www.robertniles.com/stats/stdev.shtmlhttp://www.robertniles.com/stats/stdev.shtml
http://www.investopedia.com/terms/s/standarddevhttp://www.investopedia.com/terms/s/standarddev
iation.aspiation.asp