Momo saw two charts showing the exact same numbers – but looking completely different. How does that work? Time to track down the tricks.
Trick 1
The Truncated Axis
Two classes were asked: "Do you like strawberry ice cream better than chocolate?" Class A: 8 out of 10 kids. Class B: 6 out of 10. Look at the chart – then click "rigged axis."
10
8
Class A
6
Class B
With the rigged axis, it looks like Class A has three to four times as many strawberry fans as Class B. In reality it's just 8 versus 6 – a small difference. The trick: when the axis doesn't start at 0, small differences look huge.
Remember: On any bar chart, check the numbers on the axis first, before you look at the bar heights.
Trick 2
The Distorted Sticker
"Twice as many sold!" – next to an ice cream icon drawn twice as big. Sounds fair, right? Move the slider and look closely.
🍦
Before
🍦
After (×1)
When you make an icon twice as big in height AND width, the area doesn't double – it becomes four times as big – and our eyes mostly notice area. So "twice as much" suddenly looks like "way more than double."
Trick 3
The Cleverly Chosen Time Window
Here are kidsstats' visitor numbers for the last 12 months. Pick two months and see what story you can tell with them.
to
–
Depending on which two months you pick, the same data set can show "the numbers are going up!" or "the numbers are going down!" Looking at the whole year (January to December), the trend is clearly upward – a short snippet can still claim the opposite.
Your Checklist
Before you trust a chart
1. Where does the axis start? At 0, or was a piece cut off?
2. Are the symbols drawn the same size? Or was one made bigger on purpose, to seem more impressive?
3. What time period is shown? A short snippet can tell a very different story than the longer stretch of time before and after it.
4. Who made the chart, and why? Is someone trying to sell me something or convince me of something? That doesn't automatically make it wrong – but it's worth a closer look.
You did it!
What you know now
✅ A truncated axis makes small differences look huge.
✅ Bigger symbols seem far more impressive than the real difference.
✅ A short time window can tell a different story than the full picture.
✅ Before believing it: check the axis, symbol size, time window, and source.