Question

As you peruse the internet on statistical concepts, you find that some web-pages show
a standard deviation being calculated with n in the denominator and others show a
standard deviation calculated with (n − 1) in the denominator (or both!). How does
this make sense and when would you use one or the other?

Answer 1

We know that,

If we want to calculate population standard deviation then it is n at the denominator

And

If we want to calculate sample standard deviation then it should be (n-1) at the denominator because this gives very accurate unbiased estimator of population standard deviation.

So, use (n-1) at the denominator if sample standard deviation is asked(i.e, if you found "sample" word in the problem)otherwise n is used commonly.

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