DISTRIBUTIONSSTARTER◉ LIVE LAB

Central Limit & Six Sigma

Sample averages settle to normal; variation reduction pays until returns diminish.

μ+σ−σ
μ center, thin tails · recreated schematic

How it works

  • Average enough independent samples and the average goes normal.
  • Bigger n shrinks wobble by √n — quadrupling halves noise.
  • Six Sigma is this idea weaponized against variation.
Use → Quality programs, polling margins, A/B sizing.
Watch out → Tiny samples wearing normal-theory confidence intervals.
Try it → Average 30 coin-flip batches; watch the histogram bell up.
REDCAPE jobs → Reason · Communicate
Free sources → Coursera M2 (CLT & Six Sigma) • OpenIntro Statistics (CC BY-SA)
INTERACTIVE LABoriginal recreation — poke it
16
Average of 1 dice, 3,000 rolls
MEAN
3.53
SPREAD (σ)
1.72

One die is flat. Average a few and a bell appears; the spread shrinks like 1/√n.