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lovelasagne
User

Joined: 04 Feb 2009
Posts: 1

 Posted: Wed Feb 04, 2009 6:17 pm    Post subject: Standard Deviation 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
Moderator

Joined: 06 Oct 2005
Posts: 2122
Location: Missouri, US

 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_________________
levitate
User

Joined: 17 Feb 2009
Posts: 1

 Posted: Fri Feb 20, 2009 2:23 am    Post subject: here is a good site: example of calculating standard deviation
Theodore
Moderator

Joined: 06 Oct 2005
Posts: 2122
Location: Missouri, US

 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._________________
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