SEC2_GYM · Statistics · STAT.NORMAL

Normal distribution basics

Intuition

Understand first, compress later.

Statistics describes data and separates visible patterns from random variation.

Switch representations

Normal distributionμ = 100 · σ = 15

μ ± σ · about 68 %μ ± 2σ · about 95 %mean μ

The curve is symmetric about μ = 100. Between 85 and 115 — that is μ ± σ — lie about 68 % of all values, within μ ± 2σ about 95 %, and within μ ± 3σ about 99.7 %. The further out, the flatter the curve and the rarer the value.

Formal view

You can normal distribution 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.