<p>I was going trough some Math 2 questions that were asking what is the standard deviation of the N terms. In the most of them you need to divide by N, but in the others you have to divide by N-1 to get the answer. When is N and when is N-1?</p>
<p>[Bessel’s</a> correction - Wikipedia, the free encyclopedia](<a href=“http://en.m.wikipedia.org/wiki/Bessel’s_correction]Bessel’s”>Bessel's correction - Wikipedia)</p>