A Simple Statistical Parameter for Use in Evaluation and Validation of High Throughput Screening Assays

TLDR

Identifying active compounds from large libraries is the ultimate goal of HTS assays, yet criteria for evaluating assay suitability are poorly defined, making direct comparison difficult. The study defines a screening window coefficient, the Z‑factor, to assess HTS assay quality. This coefficient reflects both assay signal dynamic range and data variation, is dimensionless, and serves as a simple statistical characteristic for each HTS assay. The Z‑factor provides a useful tool for comparing and evaluating assay quality and can be used in assay optimization and validation.

Abstract

The ability to identify active compounds (³hits²) from large chemical libraries accurately and rapidly has been the ultimate goal in developing high-throughput screening (HTS) assays. The ability to identify hits from a particular HTS assay depends largely on the suitability or quality of the assay used in the screening. The criteria or parameters for evaluating the ³suitability² of an HTS assay for hit identification are not well defined and hence it still remains difficult to compare the quality of assays directly. In this report, a screening window coefficient, called ³Z-factor,² is defined. This coefficient is reflective of both the assay signal dynamic range and the data variation associated with the signal measurements, and therefore is suitable for assay quality assessment. The Z-factor is a dimensionless, simple statistical characteristic for each HTS assay. The Z-factor provides a useful tool for comparison and evaluation of the quality of assays, and can be utilized in assay optimization and validation.