z-Score

Updated: 2018-07-01

Formula

z=xμδz = { 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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