STDEV.P measures spread when your data is the entire group, not a sample. The P version divides by n instead of n−1, so it comes out a little smaller than STDEV.S.
Syntax
=STDEV.P(number1, [number2], ...)
Argument
What it means
number1…
The full population.
Examples
Example 1
=STDEV.P(B2:B13)
Spread of all 12 monthly sales figures for the year.
💡 Not sure which one? If waiting longer or asking more people would give you more rows, it is a sample: use STDEV.S.
