measures of dispersion

• Measures of dispersion

  • Range
  • Standard deviation
• range

  •  the difference between highest to lowest value (sometimes 1 is added if values have been rounded up or down)
  • Strength = easy to calculate
  • Arrange values in order and subtract largest from smallest - easier than the standard deviation
  • Limitation = doesn’t account for the distribution of the scores
  • range doesn’t indicate whether most numbers are closely grouped around the mean or spread out evenly
• standard deviation

  • Measure  of the average spread around the mean - the larger the standard deviation, the more spread out the data is
  • Strength = more precise than the range
  • Includes all values within the calculation => more accurate picture of the overall distribution of data set
  • Limitation = may be misleading
  • Can be distorted by extreme values OR extreme values may not even be revealed