Resistant measures of location

• Median

  • Central value when data are ranked (P0.5)
    • Middle value for odd number of observations
    • Average of middle two values for even number
  • Only determined by order of data
  • Resistant to outliers

• Trimmed mean

  • Average based on a “trimmed” sample
  • Generally trim 25% of highest AND lowest values
  • Resistant to extreme values

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