How to Calculate Population Standard Deviation with STDEV.P

When you have every value — a whole class, every store — STDEV.P gives the exact spread. Learn when to use it.

You will learn to

• Calculate a population standard deviation
• Set a cut-off one standard deviation above the mean
• Compare the spread of two measures

How it works

STDEV.P calculates the standard deviation of an entire population: it divides the squared deviations by n rather than n − 1. Use it when your data contains every member of the group you are describing — all students in a class, all branches of a company, all items in a finished batch — and you are not generalising to anyone else.

If the data is only a sample of a larger group, use STDEV.S. With large data sets the two converge; with small ones STDEV.P is noticeably smaller.

=STDEV.P(B2:B10)