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Mathematical Requirements for Research Methods

Correlation coefficients, pie charts and translating between data forms

  • 3 things to know
  • Component 01

Overview

Recall questions on interpreting scatter diagrams and correlation coefficients, translating between graphical, numerical and algebraic forms, calculating pie chart sectors, and choosing pie charts, line graphs and other displays.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Numbers

Why is a scatter diagram not the right display for an experiment comparing two conditions?

Key term

When is a pie chart a suitable display?

Key term

What does the closeness of the points to a straight line indicate?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What does the closeness of the points to a straight line indicate?

    Model answer

    The strength of the correlation, with tightly clustered points showing a strong relationship and widely scattered points a weak one.

  2. 2

    A correlation coefficient of −0.78 is calculated. Describe the relationship.

    Model answer

    It is a strong negative correlation, so as scores on one co-variable rise, scores on the other tend to fall.

  3. 3

    What is the possible range of values for a correlation coefficient?

    Model answer

    From −1 through 0 to +1.

  4. 4

    Why is a scatter diagram not the right display for an experiment comparing two conditions?

    Model answer

    An experiment tests a difference between conditions, which is shown by a bar chart of the condition means. A scatter diagram displays the strength and direction of a relationship between two measured variables, which is a correlational question.

  5. 5

    What is meant by translating information between graphical, numerical and algebraic forms?

    Model answer

    Moving between a set of raw scores, a summary such as a mean or a coefficient, a visual display and a symbolic expression such as a formula or an equation, while keeping the same information intact.

  6. 6

    In a study of 180 participants, 45 chose the first option. What angle would this sector occupy on a pie chart?

    Model answer

    It is 25% of the sample, so the sector is 90°.

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