Standard Deviation

September 1st, 2011
math
Standard deviation is the average distance between each data point and the mean of the data. It's defined as:

Why isn't it:

That is, why is it the square root of the average of (x-mu)^2 instead of just the average of |x-mu|? How is the squared version more useful?

Update 2011-09-01 I had left out the square root on the standard deviation.

Comment via: google plus, facebook, substack

Recent posts on blogs I like:

Three cheers for the tomboy chaser

Three cheers for the tomboy chaser!

via Thing of Things January 30, 2026

2025-26 New Year review

This is an annual post reviewing the last year and setting intentions for next year. I look over different life areas (work, health, parenting, effectiveness, etc) and analyze my life tracking data. Highlights include a minimal group house, the usefulness…

via Victoria Krakovna January 19, 2026

Why I Don't Think My Braces Were Worth It

A couple weeks ago, I got my braces off. I kind of wish I had never had them, though. When I was younger, two of my teeth were sticking out, and they looked kind of funny. I thought that my teeth were just fine, and I didn't want to get braces. But s…

via Anna Wise's Blog Posts January 3, 2026

more     (via openring)