Empirical Rule

carolyn celestin

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For a distribution that is symmetrical and bell-shaped


  • Approximately 68% of the data values will lie within 1 standard deviation of each side of the mean.
  • approximately 95% of the data values will lie within 2 standard deviation.
  • approximately 99.7% (or almost all) of the data values will lie within 3 standard and deviations on each side of the mean.