correlation vs linear model

[jerlich]

First, just want to say that i love this! So thanks for the work.

Maybe you can add a little note for the section on correlations:
There is a difference between corr(x,y) and lm(y ~ 1 + x). Correlation is commutative corr(x,y) = corr(y,x) but lm(y ~ 1 + x) ≠ lm(x ~ 1 + y). It's especially relevant when both x and y contain measurement error.

A good reference for this is here:
https://elifesciences.org/articles/00638
The tls package in R provides one option for computing this.