Measures of Dispersion

• What do measures of dispersion calculate in a set of data?

  Variation in a set of data
• What is the range in measures of dispersion?

  • Difference between the highest and lowest scores
  • Calculation method: highest score - lowest score
  • Strengths: Easy to calculate
  • Limitations: Affected by extreme values, does not use all data
• How is the range calculated?

  By subtracting the lowest score from the highest score
• What is a strength of using the range as a measure of dispersion?

  It is easy to calculate
• What is a limitation of using the range?

  It is affected by extreme values
• What is the standard deviation (SD) in measures of dispersion?

  • It is the square root of the variance
  • A low SD indicates data is clustered close to the mean
  • Precise measure as it considers all data values
  • Limitations: Affected by extreme values
• How is standard deviation (SD) calculated?

  It is the square root of the variance
• What does a low standard deviation indicate about the data?

  More data is clustered close to the mean
• What is a strength of using standard deviation as a measure of dispersion?

  It is a precise measure where all data values are taken into account
• What is a limitation of standard deviation?

  It is affected by extreme values