Dispersion

• What are the measures of dispersion?

  Range

  Standard deviation
• What is the range?

  The difference between the highest and lowest numbers
• What are the strengths of the range?

  Quick and easy to calculate
• What is the weakness of the range?

  Affected by outliers, doesn’t take into account all the values
• What is the standard deviation?

  Tells us the average distance of each score from the mean
• What are the strengths of standard deviation?

  More precise measure of dispersion
• What are the weaknesses of standard deviation?

  Much harder to calculate than the range