# Quality Assurance Terms Glossary/Z

From Elsmar Cove Quality Assurance and Business Standards Wiki

## Z

**z Score ** - The observed value of the z statistic

**z Statistic ** - A test statistic whose distribution under the null hypothesis has expected value zero and can be approximated well by the normal curve. Usually, z statistics are constructed by standardizing some other statistic.

**z Test ** - A hypothesis test based on approximating the probability histogram of the z statistic under the null hypothesis by the normal curve.

**Zero Acceptance Sampling** - aka C=0

**Zero Defects ** - The quality concept of zero tolerance for defects.