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

Abstract

The ability to identify active compounds ("hits") 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 "suitability" 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 "Z- factor," 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.

References

Cole, S.T. , Saint Girons, I. (1994). Bacterial genomics. FEMS. Microbiol. Rev. 14:2, 139-160.

Korenberg, J.R. , Chen, X.N. , Adams, M.D. , Venter, J.C. (1995). Toward a cDNA map of the human genome. Genomics 29:2, 364-370.

Fasman, K.H. , Letovsky, S.I. , Li, P. , Cottingham, R.W. , Kingsbury, D.T. (1997). The GDB Human Genetic Database Anno. 1997. Nucleic Acids Res. 25:1, 72-81.

Gordon, E.M. , Gallop, M.A. , Campbell, D. , Holmes, C. , Bermak, J. , Look, G. , Murphy, M. , Needels, M. , Jacobs, J. , Sugarman, J. , Chinn, J. , Ruhland-Fritsch, B. , Jones, D. (1995). Combinatorial organic synthesis: Application to drug discovery. Eur. J. Med. Chem. 30:S337-S348.

Gordon, E.M. , Barrett, R.W. , Dower, W.J. , Fodor, S.P.A. , Gallop, M.A. (1994). Application of combinatorial technologies to drug discovery. 2. Combinatorial organic synthesis, library screening strategies and future directions. J. Med. Chem. 37:1385-1401.

Oldenburg, K.R. , Zhang, J.-H. , Chen, T. , Maffia, A. , Blom, K.A. , Combs, A.P. , Chung, T.D. (1998). Assay miniaturization for ultra-high throughput screening of combinatorial and discrete compound libraries: A 9600-well (0.2 microliter) assay system. J. Biomol. Screen. 3:55-62.

Stevens, M.E. , Bouchard, P.J. , Kariv, I. , Chung, T.D-Y. , Oldenburg, K.R. (1998). Comparison of automation equipment in high Throughput Screening. J. Biomol. Screen, 3:305-311.

Sittampalam, G.S. , Iversen, P.W. , Boadt, J.A. , Kahl, S.D. , Bright, S. , Zock, J.M. , Janzen, W.P. , Lister, M.D. (1997). Design of signal windows in high throughput screening assays for drug discovery. J. Biomol. Screen. 2:159-169.