Question 1

Which SD does Excel use?

Accepted Answer

STDEV.S divides by n − 1 (sample) and STDEV.P divides by n (population).

Question 2

Can the standard deviation be negative?

Accepted Answer

No. It is a square root of a sum of squares, so it is zero or positive; zero means every value is the same.

Question 3

What is a high standard deviation?

Accepted Answer

There is no fixed threshold. Judge it relative to the mean (the CV) or against values typical for your field.

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