Variance? Standard Deviation? Eureka!

[afuna]

I've been sucked into coursera, and I've started a couple math-based classes.

The last time I tried this, I stopped a few weeks in because I tried too many hard classes at the same time, and couldn't work them into my schedule. This time I'm ramping up more slowly: intermediate algebra (to brush up my skills), pre-calculus (same, but at a more accelerated pace), and data analysis.

I find statistics a challenge. I get the basic underlying concepts in an abstract manner, but find it really difficult when it comes to actually applying them. Which points to my not really understanding the basic underlying concepts, heh.

Just had my first eureka moment: I can happily parrot back that SD = square root of variance, but I never got why it mattered which one you used. And just two sentences cleared up years' worth of confusion:

"Variance is expressed in (units of x) squared. Standard deviation is often preferred because it is expressed in units of x"

GIGANTIC LIGHTBULB.

Comments

[pauamma]

Yannow, it never occurred to me to wonder about that. (The SD vs. variance thing.) And now I'm trying to decide whether I should be happy or sad that I got to skip past the wondering/puzzling it out phase and go directly from lack of awareness to enlightenment.

[afuna]

Hmmmm. I would say both :-) Because what if you'd gone through the puzzling phase but you never found out!

[pauamma]

There is that.