# Scatter graphs and correlation

A scatter graph plots pairs of data as points. Correlation describes the pattern: positive (both rise), negative (one rises, one falls) or none.

Maths (school) · Part 08: Probability and statistics · Card 8 of 8 · Last updated 2026-10-19

## Analogy

Like dots on a map showing whether two things move together.

## Example

**Reading a line of best fit**

Hours revised: 4
Line of best fit gives mark 70
Hours: 6 gives mark 85
Stronger revision, higher marks

## In practice

Ice cream sales and temperature show positive correlation.

## Practice

### Flashcards

- **What is positive correlation?** Both quantities rise together.

## Questions people ask

### What is a line of best fit?

A straight line drawn through the middle of the points, with roughly equal points on each side. It need not touch every point. You can use it to estimate one value from another within the range of the data. Do not use it to predict far outside your data, because the pattern may not continue.

### Does correlation mean one thing causes the other?

No. Two things can move together without one causing the other. Ice cream sales and sunburn both rise in summer, but ice cream does not cause sunburn. The hot weather is the cause of both. Always ask whether a third factor, such as the weather, might be behind both patterns.

## Related concepts

- [Averages](https://studyvisually.com/learn/science/maths-school/maths-school-part-8/maths-school-part-8-concept-6)
- [Mean from a frequency table](https://studyvisually.com/learn/science/maths-school/maths-school-part-8/maths-school-part-8-concept-7)

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