No σ for you!

[AnnoyedOne]

I don't know either.

As I recall we calculated sample standard deviation (by hand) in HS.

Since the difference is dividing by n or n-1 it only matters for small n. If n is large enough the difference is minor.

My guess is that engineers (HP calculator designers) typically have small n (samples) hence Sx.

A1

PS: From the footnote on p53 (p65 of the PDF) of "HP-15C Collector's Edition Owner's Handbook"

Quote:The difference between the values is small for large n, and for most applications can be ignored. But if you want to calculate the exact value of the population standard deviation for an entire population, you can easily do so: simply add, using E+, the mean (x) of the data to the data before pressing g s. The result will be the population standard deviation.