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What method is this?


hamzah

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Lets say I have three values - 917, 914 and 913. Take an average I get 915 (approx).

 

Now see how far each value is from the average...

 

917 - 915 = 2

915 - 914 = 1

915 - 913 = 2

 

(2+1+2)/3 = 2 (approx)

 

so the value is (915 +/- 2)

 

what is this method called?

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Neurocomp2003 said in post # :

....method?

this isn't a method its error measurement.

 

yeah thats what I'm doing, error measurements...but the way I calculated it...does that technique have a name or anything?

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Hamza is talking about the mean deviation.

 

The measure of how much any given observation varies from the mean is a deviation. These will have either positive or negative values. The mean of them will always be zero (as the mean is the arithmetical centre of the data). So, to calculate the mean deviation, we ignore the sign (+ or -) which gives us for each deviation the absolute deviation, shown as |d|.

 

So, the two ways of calculating the mean deviation is either:

 

Sum of |x - mean|

----------------------

             N

 

 

or

 

Sum of |d|

-------------

      N

 

 

The Standard deviation is: 

 

                                       (Sum of (X - mean)^2) 

The square root of:     -----------------------------

                                                       N

 

 

(or N-1 for the sample SD).

 

Dang! I wish I knew how to use the formula doohickey.

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