Errata: Where the Bars Begin
The idea: a bar chart that does not start at zero can make a small change look huge; ask where the axis begins, and per how many.
Read it
Who is in this book
- Uncrop An image is cropped; ask what sits outside the frame from NewsForge
- Deed Go to the original document, not a summary of a summary from NewsForge
- Danya a child of the Green Asks "how do we know?"
- Widen One number means little without something to compare it with from NewsForge
- 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
- A bar chart shows a value by the length of its bar. If the value axis starts above zero (a truncated axis), small differences are drawn as large ones, which is one of the commonest ways a chart misleads. Source
- In the case, 1,180 visits fell to 1,120, a fall of 60, about 5%. With the axis starting at 1,100 the bars are drawn 80 and 20 tall, four times apart. With 1,000 pupils and then 950, the visits per pupil are 1.18 and about 1.18.
- A rate per person (per capita) divides a count by the number of people, so that groups of different sizes, or the same group in different years, can be compared fairly. Source
Stretched
- In the case, the chart is redrawn and the question is settled in one afternoon. What we simplified: A line chart showing a small change over time is sometimes drawn with an axis that does not start at zero, and that can be fair if it is clearly marked. A bar chart is different, because the length of the bar is the value.
Made up
- The library, its log, Jun, Ffion, Mr Adebayo, the governors and the Green Gazette's March front page are made up. The idea of a truncated axis 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.