The Two One-Sided t-Test (TOST)

Content

This information leaflet is intended for laboratories performing significance testing for two (mean) values, or for a mean value and a reference value. Unlike the conventional t-test, which assesses whether two values are different, the Two One-Sided Test (TOST) procedure presented here evaluates whether the difference is acceptable - that ism within a specified acceptance range. Deviations in both directions are tested separately using a one-sided t-test at the chosen significance level.

The leaflet has been prepared by the Eurachem Measurement Uncertainty and Traceability Working Group to introduce the use of equivalence testing.

Availability

• Download English version (PDF, 287 kB) (Published 2026-04-17)*

Translation

Translation into other languages is encouraged for members of Eurachem. Other offers of translation should be directed to the Eurachem Secretariat for permission. The Eurachem policy on maintenance and development of Eurachem guidance, available on the Policies page, gives further information on translation.

*Publication dates are dates of website publication. English version first published on this site on 2026-04-17.

Details

Last Updated: Friday, 17 April 2026 15:10

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