Calxsolver
Subject:  Statistics

Z-score

The number of standard deviations a value lies above or below the mean.

A z-score standardizes a value so that data sets with different units and scales can be compared. A z of 0 is at the mean, positive z is above, negative below. For a normal distribution, about 68% of values lie within |z| < 1 and about 95% within |z| < 2.

Formula

z = (x − μ) / σ

Used in

Z-Score Calculator Standardize a value against a mean and standard deviation. Normal Distribution Calculator Probabilities for a normal distribution N(μ, σ). Confidence Interval Calculator Confidence interval for a population mean.

See also

Mean The arithmetic average of a set of numbers — their sum divided by the count. Standard deviation A measure of how spread out the values in a data set are around the mean. Normal distribution The bell-shaped probability distribution defined by a mean and a standard deviation.