Lesson 7 of 11
Same numbers, two stories
Show on a big screenA farm doubled all three crops in season 2. Its data was drawn as two charts. One chart showed the crops doubled. The other showed the shares unchanged.
Drag paddy in season 2. Switch between the two charts. At 80 quintals, paddy doubles.
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The rule
Neither chart cheats. Both start at zero. They differ in the question they answer.
| Chart | Question | Honest answer |
|---|---|---|
| Bar graph | What changed? | Paddy doubled, and so did every crop. |
| 100% stacked bar | What share was each crop? | The shares stayed the same. |
The bar graph shows counts, so the doubling shows. The 100% bar shows shares, and the shares did not change.
The question picks the chart. Two honest charts of one data set can leave different impressions.
Misuse is different. Someone picks the chart that fits the story they want. Then they say the data tells that story.
So ask: what does the other chart say?
Try the lab to finish this lesson.