What is Z (read: Z-factor)?
The Z -factor calculation is useful during piloting for quality assessment of assay conditions (Zhang et. al. 1999). To quantitatively rank assay conditions, perform control experiments and calculate Z from the data collected: Z’ = 1 – 3*(SDpos+SDneg)/abs(Avpos-Avneg); SDpos = SD of all positive control values SDneg = SD of all negative control values Avpos = Average of all positive control values Avneg = Average of all negative control values abs represents absolute value. 1 0.9 0.7 0.5 = Z’ The absolute minimum recommend for high throughput screening This table may differ slightly from published recommendations. However it is based on the general experience of researchers in our facility. We commonly observe that screening results rarely achieve the high quality levels seen during piloting using controls. Z’-factor Reference: Ji-Hu Zhang, Thomas D. Y. Chung and Kevin R. Oldenburg (1999). A simple statistical parameter for use in evaluation and validation of high throughput screening
