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Brain Break
Brain break
The Prior Rule
A Bayesian average mixes what a small crowd actually said with a prior — a block of dummy votes at 5.5:
rating = (dummies × 5.5 + sum of real ratings) ÷ (dummies + how many)
With zero real votes it is exactly 5.5. Each real vote nudges it toward the true mean — but a large dummy block means it takes many votes to move. That is why a brand-new 5-star game does not rocket to the top: the prior holds it down until the volume arrives.
Meet the cast
Five statisticians, each embodying one idea behind the Prior Rule.
- Priya — starts every rating at the prior — "every game starts at 5.5"
- Bayard — blends the prior with the evidence — the shrinkage average
- Vera — shows how VOLUME, not a loud few, overcomes the prior
- Dunna — counts the dummy votes and asks how many real ones it takes to move
- Sol — the mentor — asks what a rating with only three votes really tells you