Interesting. My statistics knowledge has become rusty lately. I want to re-learn the basics before reading this.
Can you tell me any resource (doesn't necessarily have to be a book)?
P.S: I'm interested in knowing stuff like 'why square-root of variance is standard deviation?". Concepts.
It's a free online statistics textbook, also available in print. I haven't used it extensively, so I can't vouch for its quality -- actually, I complain about it a bit in Statistics Done Wrong. But I've never come across a very good conceptual introduction to statistics, so this is roughly the best I know.
There are also amusing variations, like the cartoon guide to statistics:
P.S: I'm interested in knowing stuff like 'why square-root of variance is standard deviation?". Concepts.