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z-Score

Last Updated: 2021-11-19

Formula

z = x μ δ z = { x - \mu \over \delta}

where μ \mu is the mean of the population, δ \delta is the standard deviation of the population.

Alternative

mean and stdDev are strongly affected by outliers, another way is:

  • mean replaced by median
  • stdDev replaced by absolute standard deviation P65

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