Measures of Spread and Variability
When we look at data, it's not enough to know just the center (like the mean or median). We also need to understand how the data is spread out or how much it varies. This is where measures of spread come in!
Why Do We Need Measures of Spread?
Imagine two classes took the same math test:
- Class A scores: 78, 80, 82, 83, 85, 87, 89
- Class B scores: 65, 70, 75, 83, 91, 95, 100
Both classes have the same mean (average) score of 83. But are they really the same? No! In Class A, everyone scored close to the average. In Class B, scores were much more spread out, with some very high and some very low scores.
Measures of spread tell us how much the data varies from the center.