Z- factor is a measure of effect size statistics. It is used for the analysis of high-throughput methods to determine whether the signal in a particular experiment is large enough to carry out further tests.


In high-throughput methods, several hundred thousand are often performed to 10 million individual measurements of unknown samples compared with positive and negative controls. The choice of certain experimental conditions and methods of measurement called " assay ". Analysis on a large scale is expensive and time consuming. Therefore, pilot experiments are conducted on a small scale, to assess the explanatory power of these assays in advance. The Z- factor is a measure to assess the usefulness of a specific assays in a high throughput can.


Z- factor is defined by four parameters: the mean and standard deviation of the positive and negative control. The formula is:

Where: σ = standard deviation, μ = mean, n = negative, P = positive.

In practice, the z-factor can be approximated by the sample mean and standard deviation of the sample.