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Principles of Research and Application of Research Methods

Descriptive Statistics: the mean, the median and the mode

  • 3 things to know
  • AS Unit 2

Overview

Recall questions on measure of central tendency, main weakness of the mean, main disadvantage of the median and mode.

What you need to know

Answer each one before you reveal it.

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Key term

What is a measure of central tendency?

Key term

State the formula for the mean in words.

Numbers

Calculate the mean of the scores 4, 7, 9, 12 and 8.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is a measure of central tendency?

    Model answer

    A single figure that summarises a set of scores by describing the typical or average value.

  2. 2

    State the formula for the mean in words.

    Model answer

    The mean is the sum of all the scores, ∑x, divided by the number of scores, n.

  3. 3

    Calculate the mean of the scores 4, 7, 9, 12 and 8.

    Model answer

    The scores total 40 and there are 5 of them, so the mean is 8.

  4. 4

    Why is the mean described as the most sensitive measure of central tendency?

    Model answer

    It is calculated from every score in the set, so it uses all of the available information.

  5. 5

    What is the main weakness of the mean?

    Model answer

    An extreme score distorts it, pulling it away from the bulk of the data so that it no longer represents them.

  6. 6

    Why can a mean be a value that no participant could actually have scored?

    Model answer

    The mean is a calculated figure rather than an observation, so it can fall between whole units, such as a mean of 2.4 errors.

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