9.4

Correlation and scatter diagrams

Cambridge IGCSE Mathematics (0580)  · Unit 9: Statistics  · 9 flashcards

Correlation and scatter diagrams is topic 9.4 in the Cambridge IGCSE Mathematics (0580) syllabus , positioned in Unit 9 — Statistics , alongside Data collection and display, Averages and measures of spread and Cumulative frequency and box plots.  In one line: A scatter diagram (or scatter graph) is a visual representation of the relationship between two variables. It's used to determine if there is a correlation between them.

This topic is examined across Paper 1 (Core) or Paper 2 (Extended) — non-calculator — and Paper 3 (Core) or Paper 4 (Extended) — calculator.

The deck below contains 9 flashcards — 7 definitions, 1 key concept and 1 application card — covering the precise wording mark schemes reward.  Use the 7 definition cards to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.

Key definition

A scatter diagram, and what is it used for

A scatter diagram (or scatter graph) is a visual representation of the relationship between two variables. It's used to determine if there is a correlation between them.

Questions this Correlation and scatter diagrams deck will help you answer

Definition Flip

What is a scatter diagram, and what is it used for?

Answer Flip

A scatter diagram (or scatter graph) is a visual representation of the relationship between two variables. It's used to determine if there is a correlation between them.

Definition Flip

Describe 'positive correlation' as it relates to a scatter diagram. Give an example.

Answer Flip

Positive correlation means that as one variable increases, the other also tends to increase.

Example: Generally, as study time increases, exam scores increase.
Definition Flip

Describe 'negative correlation' as it relates to a scatter diagram. Give an example.

Answer Flip

Negative correlation means that as one variable increases, the other tends to decrease.

Example: Generally, as the temperature increases, the sales of winter coats decrease.
Definition Flip

What does it mean if a scatter diagram shows 'no correlation'?

Answer Flip

If there's no correlation, there's no apparent relationship between the two variables. The points on the scatter diagram appear randomly scattered.

Definition Flip

What is a 'line of best fit' on a scatter diagram, and what is its purpose?

Answer Flip

The line of best fit is a straight line drawn through a scatter diagram that best represents the trend of the data. It's used to estimate values of one variable based on the other.

Definition Flip

Explain 'interpolation' in the context of a line of best fit on a scatter diagram.

Answer Flip

Interpolation is using the line of best fit to estimate a value *within* the range of the original data. It is generally considered a reliable estimate.

Definition Flip

Explain 'extrapolation' in the context of a line of best fit on a scatter diagram.

Answer Flip

Extrapolation is using the line of best fit to estimate a value *outside* the range of the original data. This is less reliable than interpolation.

Key Concept Flip

The number of ice creams sold at the beach and the temperature on the day show positive correlation. True or False? Explain.

Answer Flip

True. Warmer temperatures typically lead to higher ice cream sales, indicating a positive relationship between the two variables.

Key Concept Flip

Sketch a scatter diagram showing strong negative correlation.

Answer Flip

The scatter diagram should show points generally clustering around a line that slopes downwards from left to right. The tighter the points are to the line, the stronger the correlation.

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9.3 Cumulative frequency and box plots 9.5 Histograms

Key Questions: Correlation and scatter diagrams

What is a scatter diagram, and what is it used for?

A scatter diagram (or scatter graph) is a visual representation of the relationship between two variables. It's used to determine if there is a correlation between them.

Describe 'positive correlation' as it relates to a scatter diagram. Give an example.

Positive correlation means that as one variable increases, the other also tends to increase.

Example: Generally, as study time increases, exam scores increase.
Describe 'negative correlation' as it relates to a scatter diagram. Give an example.

Negative correlation means that as one variable increases, the other tends to decrease.

Example: Generally, as the temperature increases, the sales of winter coats decrease.
What does it mean if a scatter diagram shows 'no correlation'?

If there's no correlation, there's no apparent relationship between the two variables. The points on the scatter diagram appear randomly scattered.

What is a 'line of best fit' on a scatter diagram, and what is its purpose?

The line of best fit is a straight line drawn through a scatter diagram that best represents the trend of the data. It's used to estimate values of one variable based on the other.

Tips to avoid common mistakes in Correlation and scatter diagrams

More topics in Unit 9 — Statistics

Correlation and scatter diagrams sits alongside these Mathematics decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.

Cambridge syllabus keywords to use in your answers

These are the official Cambridge 0580 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.

scatter diagram scatter graph correlation positive correlation negative correlation no correlation line of best fit interpolation extrapolation trend

Key terms covered in this Correlation and scatter diagrams deck

Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.

Scatter diagram, and what is it used for
Describe 'positive correlation' as it relates to a scatter diagram. Give an example
Describe 'negative correlation' as it relates to a scatter diagram. Give an example
What does it mean if a scatter diagram shows 'no correlation'
'line of best fit' on a scatter diagram, and what is its purpose
Explain 'interpolation' in the context of a line of best fit on a scatter diagram
Explain 'extrapolation' in the context of a line of best fit on a scatter diagram

Related Mathematics guides

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