Z-Score denotes the number of standard deviations a data value \(x_{i}\) is from the mean.

\[Z_{i}=\frac{x_{i}-\bar{x}}{s}\]

An observation's z-score is a measure of the relative location of the observation in a data set.

An observations' data value greater than the sample mean will have a zscore greater than zero.

An observation's data value less than the sample mean will have a z-score less than zero.

An observation's data value equal to the sample mean will have a z-score of zero.