Enter the mean and standard deviations of the positive and negative controls to determine the Z-factor.

## Z Factor Formula

The following formula is used to calculate a Z factor.

Zf = 1 – [ 3*(σp + σn)/|μp – μn| ]

- Where Zf is the Z-factor
- μ are the means of the positive and negative controls
- σ are the standard deviations of the positive and negative controls

## Z Factor Definition

Z factor, which is not the same as a z-score, is a measure of the statistical effect size.

## Z Factor Example

How to calculate a z-factor?

**First, determine the the means.**Calculate the means of the positive and negative controls.

**Next, determine the standard deviations.**Calculate the standard deviations of the same positive and negative controls.

**Finally, calculate the z factor.**Calculate the z factor using the equation above.

## FAQ

**What is a z-factor?**

A z-factor is a measure of whether the response in a specific assay is large enough to warrant further attention.