Quote:
In Reply to Parent Post by Statistical Steven
I wish Microsoft would do away with the STDEVP function. It has no use. The difference is that STDEV divides by n1 and STDEVP divides by n. Can anyone tell me when you would use STDEVP?

I think I've also answered this on the ASQ board from a question there. But here goes:
The formula for sigma (STDEVP) is the maximum likelihood estimator for the population standard deviation. However, it is a biased estimator. If you only have a sample of the population (and consider  if the "future" is part of your population, you still only have a sample), STDEVP will have a bias in it. If you repeatedly sample from a population, you will notice that the average STDEVP values will not tend to match the actual population standard deviation. However, if you use STDEV (dividing by n1), the average of the STDEV's will converge on the population standard deviation.