https://doi.org/10.1351/goldbook.14204
Dimensionless statistical parameter used extensively in biomolecular screening, and a characteristic of an assay without the intervention of test compounds. It provides a practical index of the quality and reliability of the assay, and can be used as a guide to assay development and optimization. \[Z' = 1 - 3(\sigma_{\rm{c^{+}}} + \sigma_{\rm{c^{-}}})/(\vert\mu_{\rm{c^{+}}} - \mu_{\rm{c^{-}}}\vert)\] where \(\sigma_{\rm{c^{+}}}\) and \(\sigma_{\rm{c^{-}}}\) are the standard deviations of the high and low controls and \(\mu_{\rm{c^{+}}}\) and \(\mu_{\rm{c^{-}}}\) are the means of the high and low controls, respectively.
A graphical illustration of the parameters used in the calculation of \(Z'\) is provided below.
Note: The useful range of \(Z'\) values is from 0 (very poor) to +1 (excellent). In most cases, a \(Z'\) factor greater than \(\pu{0.5}\) is required for an assay to be accepted for high-throughput screening.