Homeschool World Forum

lovelasagne · User Joined: 04 Feb 2009 Posts: 1

I'm not great at maths and trying to work out standard deviation for some numbers. All the example calculations I find are very hard to follow. Could someone give a link to an easy example if he/she knows one.

Theodore · Posted: Fri Feb 06, 2009 7:34 pm Post subject:

I'm going to use the example numbers 12, 3, 10, and 7.

1) Find the average of your numbers:

(12 + 3 + 10 + 7) / 4 = 32 / 4 = 8

2) Find the distance of each number from the average:

12 - 8 = 4, 3 - 8 = -5, 10 - 8 = 2, 7 - 8 = -1

3) Square each of these distances:

4 * 4 = 16, -5 * -5 = 25, 2 * 2 = 4, -1 * -1 = 1

4) Find the average of the squares:

(16 + 25 + 4 + 1) / 4 = 46 / 4 = 11.5

5) Take the square root of this number, you have your standard deviation:

sqrt(11.5) = about 3.3912
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The Farming Game - Software Edition for Mac and PC
The board game has sold over 350,000 copies worldwide, garnered many awards, is used by over 2,000 schools, and is used extensively by homeschoolers.

levitate · User Joined: 17 Feb 2009 Posts: 1

here is a good site:

example of calculating standard deviation

Theodore · Posted: Mon Feb 23, 2009 9:44 pm Post subject:

It gives the formula, but it doesn't really explain what it means. I personally prefer the Wikipedia article, if I were going to give a link rather than posting an explanation.
_________________
The Farming Game - Software Edition for Mac and PC
The board game has sold over 350,000 copies worldwide, garnered many awards, is used by over 2,000 schools, and is used extensively by homeschoolers.