Lesson L2

L2 Scatter diagrams, regression lines and correlation Quiz: AQA Maths, Unit 11

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson L2, Scatter diagrams, regression lines and correlation: 20 multiple choice questions for the AQA Maths (7357), Unit 11: Statistics, written with Revision Ninja.

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The 20 questions

  1. What does the statement correlation does not imply causation mean?

    • A strong correlation proves a causal link
    • Correlation is always zero for real data
    • Correlation applies only to categorical data
    • A strong correlation can arise from a third factor or coincidence, so it does not prove one variable causes the other

  2. What does positive correlation mean?

    • As one variable increases, the other tends to increase
    • The variables are unrelated
    • As one variable increases, the other decreases
    • The two variables are always equal

  3. For strong negative correlation, the points lie close to which kind of line?

    • A horizontal line
    • A circle
    • A straight line with positive gradient
    • A straight line with negative gradient

  4. Within what range must the product moment correlation coefficient r lie?

    • -1 to 1 inclusive
    • 0 to infinity
    • 0 to 1 inclusive
    • -10 to 10 inclusive

  5. A scatter diagram shows two distinct sections of points. What does this suggest?

    • That a regression line is not needed
    • An error in the data
    • The data may come from two or more sub-populations
    • That the variables are independent

  6. A correlation coefficient of r = -0.9 is found for two variables. Which is the best interpretation?

    • A strong negative linear correlation
    • No correlation
    • A perfect positive correlation
    • A weak positive correlation

  7. A regression line of exam score on hours of revision has gradient 3.5. What is the correct interpretation?

    • On average, each extra hour of revision is associated with 3.5 more marks
    • Each hour of revision causes exactly 3.5 marks
    • There is no relationship between revision and score
    • A student with no revision scores 3.5 marks

  8. A point lies far away from the rest of a scatter diagram and pulls the line of best fit towards it. What is it called?

    • A correlation coefficient
    • A residual of zero
    • An outlier
    • A cluster

  9. A correlation coefficient of 0.05 is calculated. Which is the best interpretation?

    • The variables are perfectly negatively correlated
    • The variables are strongly positively correlated
    • There is almost no linear correlation between the variables
    • Every point lies on a straight line

  10. A regression line is used to predict a value for an x-value far outside the range of the data. What is this called and how reliable is it?

    • Extrapolation, which may be unreliable
    • Interpolation, which is always reliable
    • A correlation of zero
    • A sampling error that cannot be fixed

  11. Ice cream sales and drowning incidents have a correlation of 0.8. What is the best conclusion?

    • The variables are strongly positively correlated, but a common cause such as hot weather may explain both, so causation cannot be concluded
    • Drowning causes ice cream sales to rise
    • Ice cream causes drowning
    • The correlation is negative

  12. All points lie exactly on a straight line with negative gradient. What is the value of r?

    • -1
    • 0
    • -0.5
    • 1

  13. A scatter diagram has two groups of points, each showing little correlation within itself, but a strong overall pattern. What should be done?

    • Report only the overall correlation
    • Remove the second group as errors
    • Analyse the groups separately, since the overall correlation may be misleading
    • Ignore the scatter diagram

  14. A correlation coefficient of 0.6 is found between two variables. Which statement is best?

    • There is no association between the variables
    • The variables have a moderate positive linear association
    • One variable causes 60% of the other
    • The variables have a perfect positive linear relationship

  15. Shoe size and reading score are positively correlated among children. What is the best explanation?

    • Bigger feet cause better reading
    • Age is a lurking variable that increases both
    • Reading makes feet grow
    • The correlation must be zero

  16. A scatter diagram shows points forming a clear U-shape. What is likely to be true of Pearson's r?

    • r equals the gradient of the points
    • r is close to zero, despite a clear relationship, because the relationship is non-linear
    • r is exactly -1
    • r is close to 1 because the points rise

  17. A model gives value y = 50 - 2x, with x the age of a car in years and y the value in thousands of pounds. What does the intercept 50 represent?

    • The depreciation per year
    • The average age of the cars
    • The age at which the value is zero
    • The predicted value of a new car, in thousands of pounds, when age is zero

  18. Using y = 50 - 2x for car value y in thousands of pounds and age x in years, what does the gradient -2 mean?

    • The value falls by 50 thousand pounds each year
    • The age increases by 2 years each time
    • The value rises by 2 thousand pounds each year
    • The value falls by 2 thousand pounds per extra year on average

  19. If every x-value in a dataset is multiplied by 2, what happens to the correlation coefficient r?

    • It doubles
    • It stays the same
    • It halves
    • It becomes negative

  20. A correlation coefficient is calculated from only 5 data points. What caution applies?

    • Small samples can give large apparent correlations by chance, so the result is unreliable
    • Five points always give r equal to zero
    • Larger samples are never needed
    • Five points always give a perfect correlation

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