# AnalyticBridge

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If I were to explain degrees of freedom in layman terms (without using any statistical jargons) how do I do it?

Also, can someone help me understand as to why (n-1) is used instead of n in the denominator while computing standard deviation.I did go through the reasoning posted on a few forums (that it has to do with degrees of freedom and depends on whether data is from a sample or the population itself)  but did not completely understand it.Most statistical books conveniently give a brief explanation which is not complete and say that it is beyond scope!

Thanks.

Regards,

Sharath

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### Replies to This Discussion

Hi

to get an unbiased estimation of the standard deviation you have to divide by n-1. You get an explanation why in http://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation

Hope this helps,

Tomas Keller

Imagine i ask u to choose 5 numbers that sum up to 100.

For simplicity sake u tell me the 5 no.s are 20, 20, 20, 20, 20.

But when you utter 20 fourth time, i tell you to stop and ask you what was our goal

you tell me that the goal was to choose 5n.o s that sum up to 100. So at this point i ask you how much total we have. you reply we have 80. So to get to 100, i ask how much more we need.

You tell me that is simple 100 -80 = 20, i.e another 20.

So here in this case u had degree of freedom to choose only 4 numbers i.e (20,20,20,20). Due to the specified condition of getting 5 no.s summing upto 100, the 5th number chose itself,

hence the saying N-1. (5-1 = 4 is your degree of freedom).

Hope i could explain your query.

Regards

Venkat