Not to be confused with z-score or z-value.
This article is about the Z-factor in statistics. For the gas compressibility factor, see Compressibility factor.
The Z-factor is a measure of statistical effect size. It has been proposed for use in high-throughput screening (where it is also known as Z-prime,[1] and commonly written as Z') to judge whether the response in a particular assay is large enough to warrant further attention.