GCSE · Scatter graphs & correlation

Scatter graphs & correlationExam-style questions

Why one point on a scatter graph is one individual measured twice, how to describe correlation by type and strength in the words of the question, why a correlation never proves a cause, and how to place a line of best fit — through the bulk of the data, balanced either side, ignoring a genuine outlier.

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10 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try

DifficultyAllLevel 1Level 2Level 3Level 4Level 5
  1. 1
    A supermarket recorded, for each of 1212 weeks last winter, the number of woolly hats it sold and the number of tins of soup it sold. The scatter graph shows this information.1001502002503006007008009001000110012001300Woolly hats soldTins of soup sold(a) Describe the correlation shown by the scatter graph.

    (b) The manager says: "This shows that selling woolly hats affects how much soup our customers buy."

    Explain why the scatter graph does not support what the manager says.

    (c) The manager wants a line of best fit to be drawn, and insists that it must pass through (0, 0)(0,\ 0).

    Explain why drawing the line through (0, 0)(0,\ 0) would not be sensible here.
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