S3 · Statistics · STAT.BIVARIATE.INTRO

Bivariate data and regression basics

Intuition

Understand first, compress later.

Statistics describes data and separates visible patterns from random variation.

Switch representations

Scatter plotr ≈ 0.99

data pointsleast-squares line

12 pairs of values. The cloud runs from bottom left to top right (positive): a very strong association, r ≈ 0.99. The least-squares line makes the sum of squared vertical distances as small as possible; its slope says how much y grows on average when x increases by 1.

Formal view

You can bivariate data and regression basics when you can recognise the underlying objects, select valid rules and check each step for equivalence or logical implication.

Why does it work?

This skill sits on a prerequisite network. If a step is unstable, repair the missing prerequisite instead of merely doing more items of the same type.