Measures of dispersion

• What is the range?

  Highest - lowest (sometimes adding 1)
• What is a strength of the range?

  Easy to calculate
• What is a weakness of the range?

  Unrepresentative - only uses the extreme values
• What is the standard deviation?


  A measure of the spread or dispersion of a set of data values.
• What is a strength of standard deviation?

  More precise - included all values
• What is a weakness of the standard deviation?

  Distorted by extreme values which may not be revealed