The tutor continues his discussion about population standard deviation, denoted σ, versus sample standard deviation, denoted s.

In yesterday’s post I gave the formulas for σ and s. Of course, many people use their hand calculators to find the standard deviation. (You can find out how to do so on several different calculators by searching this site:) Sometimes in introductory statistics, to simplify matters, students are encouraged to use σ rather than s. What practical difference might it make?

Example: Find σ and s for the following data list:

-11.1, 17, 0, 14.4, 25, 31, 19.7, 8.9, 2, 9.1, 7, 4.4, 15, 21, 29

Solution:

This time I used the Casio fx-260solar. You can find out how to do so here.

σ=11.15702868

s=11.54862185

s is greater by about 3.5%, which is probably not a significant amount in some contexts. However, it’s wise to check with your instructor which they prefer.

I’ll be talking more about σ vs s :)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.