How Spread Out Is Your Data? Range, IQR, and Beyond
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How Spread Out Is Your Data? Range, IQR, and Beyond
For grown-ups
Companion summary
Have you ever wondered why two football teams can have the same average score but play completely differently? Doctors and scientists use spread to spot when results are dangerously unusual, not just average. In a class test, if everyone scores between 48 and 52, the spread is tiny — but scores from 10 to 95 tell a very different story. When you feel ready, try finding the range and interquartile range of your own data set and compare what each one reveals.
Same Average, Different Story
Same Average, Different Story
Here are the daily temperatures (°C) for two different cities last week: City A: 18, 19, 20, 21, 22 City B: 5, 12, 20, 28, 35 Both cities have the same mean temperature — 20 °C. But would you pack the same clothes for both trips? Think about why one city feels much harder to plan for than the other. The difference you are noticing is called spread.
💭 Think about this
Without calculating anything yet: which city's temperatures are more spread out, and how can you tell just by looking at the numbers?