A standardized value, or [latex]z[/latex]-score, is a statistical measure that describes how many standard deviations a data point is from the mean of the data set. It is used to standardize scores on different scales to a common scale with a mean of 0 and a standard deviation of 1.

[latex]z=\dfrac{\text{Observed Value}-\text{mean}}{\text{standard deviation}} = \dfrac{x-\mu}{\sigma}[/latex]

where [latex]x=[/latex] the value of the observation, [latex]\mu=[/latex] the population mean, [latex]\sigma=[/latex] the standard deviation, and [latex]z=[/latex] the standardized value (or [latex]z[/latex]-score).