Measures of Dispersion

• Not "Where is the middle of the data?" but "How spread out is the data?"
• A quick version is the range
  • range = high - low
• standard deviation measures how much the data differs from the mean.
  • s for a sample, σ for a population.
  • s = sqrt((Σ(x-x̄)²/(n-1)))
  • For small data sets

    •  x     x- x̄   (x- x̄)2
             

• The higher any of these measurements are, the more spread out the data is.
• Do some problems.