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:

The structure of ideological abuse

Standing on your spiritual own two feet

via Thing of Things March 9, 2026

The Newest Technology in Frozen

There are lots of different things in Frozen that are new-ish, but my dad and I were wondering: what is the actual newest thing in Frozen? This led me to watch Frozen a lot while taking notes. Some of the things I found included: Elastic hair-ties A safety …

via Lily Wise's Blog Posts March 1, 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

more     (via openring)