Z' Does Not Need to Be > 0.5. (October 2020)

• Record Type: Journal Article
• Authors: Bar, Haim; Zweifach, Adam
• Is Part Of: SLAS discovery. Volume 25:Number 9(2020)
• Page Start: 1000
• Page End: 1008
• Publication Date: 2020-10
• Subjects: cell-based assays -- phenotypic drug discovery -- assay development -- screening metrics; Drugs -- Analysis -- Periodicals; Drugs -- Testing -- Periodicals; Biomolecules -- Analysis -- Periodicals; Biomolecules -- Analysis; Drugs -- Analysis; Drugs -- Testing; Drug Evaluation, Preclinical; Molecular Biology -- methods; Periodicals; Periodicals; 615.1
• DOI: 10.1177/2472555220942764
• Languages: English
• ISSNs: 2472-5552

Abstract

The assay metric Z' has come to play a critical gatekeeping role in determining whether high-throughput assays can be performed. While Z' is commonly required to be > 0.5, this expectation is not well supported. Requiring Z' > 0.5 likely prevents many potentially useful phenotypic and cell-based screens from being conducted, and causes other assays to be conducted under extreme conditions that may prevent activity from being found. We used power analysis and a novel numerical simulation approach to determine how Z' reflects assay performance under a variety of conditions. Our results show that assays with Z' > 0.5 perform better than assays with lower Z', but when an appropriate threshold is selected, assays with Z' < 0.5 can almost always find useful compounds without generating too many false positives. We provide a method that will allow researchers to estimate how to set an appropriate threshold for their assay. We suggest that instead of always requiring Z' > 0.5, assays with Z' < 0.5 should be performed when they can be justified in terms of the importance of the target and the limitations of alternate assay formats.