S4StatisticsFoundation & Higher

Scatter Graphs

A scatter graph plots two things against each other to see if they are linked. The pattern of the points tells you the type of correlation, and a line of best fit lets you make predictions.

35 min Video by Maths Genie AQA GCSE Maths
Scatter GraphsWatch the walkthrough, then read the notes below.
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What you'll learn

  • Plot a scatter graph
  • Describe the type of correlation
  • Draw a line of best fit
  • Use it to estimate values
1

Correlation

correlation: as one goes up, so does the other. correlation: as one goes up, the other goes down. correlation: no clear pattern. Correlation does not prove one thing causes the other.

2

Line of best fit

Draw a straight line that follows the trend, with roughly as many points above as below. Use it to predict a value, but be wary of far beyond the data — it becomes unreliable.

1As hours increase, scores increase.
2That is positive correlation.
AnswerPositive correlation

Tip — Predicting inside the data range (interpolation) is reliable; far outside (extrapolation) is not.

Remember these

Direction of correlation.
Follow the trend.

Watch out for these

Saying correlation proves causation.
A link does not prove one thing causes the other.
Forcing the line of best fit through the origin.
It just follows the trend, with points balanced either side.

Key takeaways

  • Positive: both rise; negative: one rises as the other falls.
  • Line of best fit follows the trend for predictions.
  • Correlation ≠ causation; avoid extrapolating too far.

Test yourself

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