Errata: The Best Month
The idea: a very bad month is usually followed by a more ordinary one; measure a change from the usual, not from the worst, before you give anyone the credit or the blame.
Read it
Who is in this book
- Sofia The spread matters as much as the average — every team has high and low days from InferForge
- Danya a child of the Green Asks "how do we know?"
- Kiran Two things moving together is not one causing the other from InferForge
- Yara Only a fair, random test can show what a choice really does from InferForge
- Attest Every claim names its source, and a correction names one too from NewsForge
- Tara a child of the Green Listens longest, speaks last
Every recurring character has a short tune, so you can tell who is on stage before a word is said. The tunes play only when you tap, and the Reading Access sound switch turns them off.
The Honest Page
Which parts of this story are true, stretched or made up?
True
- Regression to the mean is the pattern that when one measurement is unusually extreme, the next one of the same thing is likely to be closer to its usual level, simply because extreme results are partly luck. Source
- It explains why praise after an unusually good result can seem to make people do worse next time, and blame after an unusually bad one can seem to make them do better, even when the praise and blame changed nothing. Source
- In the case, Route 7 averaged about 80% on time from September to February and 80% from May to July; March to April rose 23 points, from an unusually bad month.
Stretched
- In the case, one clear reason explains the bad month: roadworks on the ring road that ended in late March. What we simplified: Real bad months often have several causes at once, and some have none that anyone can find. Regression to the mean does not need a reason: even pure chance makes the month after the worst one look better.
Made up
- Route 7, the bus company's figures, the year-end awards, Ollie, Ms Kowalski, Mr Dunn, Mr Pettit and the ring-road works are made up. Regression to the mean is real.
Tara’s sentence
The case stops where Tara speaks. Write the sentence you would have said. It stays on this device.
Kept.
Your sentence lives on this device. Nothing is sent anywhere.
Ring the hammer for someone
Pick this book for someone younger. The link carries only the book, and it will wait for them on the Green.