Standart deviation

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Re: Standart deviation

by x2suresh » Sun Feb 22, 2009 6:38 am
4meonly wrote:OA D

standard deviation will not change if you add/subtract same number to list.

s-2,r-2, t-2
0 =s-s , r-s, t-s

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Re: Standart deviation

by Ossa » Mon Feb 23, 2009 4:03 pm
Just to clarify, Standard deviation is a measure of dispersion of points around a certain mean and that is why subtracting the same number from all values only shifts the mean but dispersion remains the same and so the standard deviation does not change.
4meonly wrote:OA D
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by welcome » Mon Feb 23, 2009 7:29 pm
x2suresh,
Can you please tell me, in your solution, how come

0 =s-s , r-s, t-s
is considered as

0,s-t,s-r ???

because for making then equal we need to multiply by -1, which will chnage SD.

Please someone help me in this concept.
Shubham.
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by x2suresh » Mon Feb 23, 2009 7:40 pm
welcome wrote:x2suresh,
Can you please tell me, in your solution, how come

0 =s-s , r-s, t-s
is considered as

0,s-t,s-r ???

because for making then equal we need to multiply by -1, which will chnage SD.

Please someone help me in this concept.

it won't make any difference.

distance between r and s = distance between s and t


Its like you are moving all dispersion points values from poistive teritory into negative terriotory, but S.D will be the same.

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by welcome » Mon Feb 23, 2009 7:46 pm
Thanks, x2suresh, That was a quick point to note for me.
Shubham.
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