A-level · Data presentation

Measuring correlation (the PMCC)Exam-style questions

The product moment correlation coefficient r as a number between −1 and 1 measuring linear correlation — computing it from the summary statistics S_xy, S_xx, S_yy, interpreting it in context, and why coding leaves it unchanged.

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15 questions · A-level level · mark scheme and worked solution on each · no sign-up to try

DifficultyAllLevel 2Level 3
  1. 1
    For a set of bivariate data, Sxy=100S_{xy} = 100, Sxx=72S_{xx} = 72 and Syy=152S_{yy} = 152. Find the product moment correlation coefficient rr, to 3 decimal places.
    Level 2 · 2 marksTry it
  2. 2
    For a set of bivariate data, Sxy=60S_{xy} = 60, Sxx=90S_{xx} = 90 and Syy=160S_{yy} = 160.

    Calculate the product moment correlation coefficient. (2 marks)
    Level 2 · 2 marksTry it
  3. 3
    For each of the following, describe the correlation and suggest what it means in context.
    (a) Hours of revision and exam mark: r=0.92r = 0.92. (2 marks)
    (b) Shoe size and reaction time: r=−0.15r = -0.15. (1 mark)
    Level 2 · 3 marksTry it