# Difference between the sum of squared deviations and standard deviation?

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#1
I was watching a video and for both they said they show the average distance from the mean, but how when they have different formulas?
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3 weeks ago
#2
(Original post by kenrepjm)
I was watching a video and for both they said they show the average distance from the mean, but how when they have different formulas?
Neither of them show the average distance from the mean: Assuming this is A-level, you're unlikely to be dealing with the average distance from the mean, which has a different formula to the standard deviation.

The "standard deviation" is a measurement of spread about the mean, and in that regard it's akin to, but not the same as, the average distance from the mean.

The "sum of squared deviations" is just that, a sum, not an average; although it is used in the calculation of the standard deviation.
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#3
(Original post by ghostwalker)
Neither of them show the average distance from the mean: Assuming this is A-level, you're unlikely to be dealing with the average distance from the mean, which has a different formula to the standard deviation.

The "standard deviation" is a measurement of spread about the mean, and in that regard it's akin to, but not the same as, the average distance from the mean.

The "sum of squared deviations" is just that, a sum, not an average; although it is used in the calculation of the standard deviation.
Thanks! I'm not sure if I'll be asked this in A Level but assuming I'm asked what is the average distance from the mean (in order to find outliers) would I use standard deviation?
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3 weeks ago
#4
(Original post by kenrepjm)
Thanks! I'm not sure if I'll be asked this in A Level but assuming I'm asked what is the average distance from the mean (in order to find outliers) would I use standard deviation?
If you're looking for outliers you would look from those data points beyond a certain number of standard deviations from the mean.

The term "average distance from the mean" shouldn't come up.
1
#5
(Original post by ghostwalker)
If you're looking for outliers you would look from those data points beyond a certain number of standard deviations from the mean.

The term "average distance from the mean" shouldn't come up.
Thank you!
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