Precision

Measurement consistency

Precision is defined in ICH Q2(R1), Validation of Analytical Procedures, as "the closeness of agreement (degree of scatter) between a series of measurements obtained from multiple sampling of the same homogeneous sample under the prescribed conditions". In analytical method validation precision is required to be demonstrated for any quantitative test (excludes limit tests which have a pass/fail acceptance criteria and identity tests). Precision is broken down into repeatability and intermediate precision. Repeatability requires a minimum of nine determinations such as triplicates of three concentrations to demonstrate there is no variance in precision due to concentration or happenstance. Intermediate precision may be demonstrated using determinations with some degree of variance such as instrument used, varing dates of analysis, and differing operators.