Precision

Details

Precision is the scatter of results when the same homogeneous sample is measured several times under prescribed conditions, and is distinct from accuracy, which is closeness to the true value — results that agree closely with each other but sit to one side are precise but not accurate. ICH Q2(R2) divides precision into three levels, repeatability (same conditions, short interval), intermediate precision (different days, environments, analysts, equipment), and reproducibility (between laboratories); repeatability is confirmed by at least 9 determinations covering the reportable range (for example three concentrations by three replicates) or at least 6 determinations at 100% of the test concentration, and standard deviation, relative standard deviation, and confidence interval are reported (§3.3.2). Inspections cite validation completed on repeatability alone with intermediate precision omitted, RSD acceptance criteria with no justification, artificially prepared samples used without the reason being recorded, and instrument calibration programmes under 21 CFR 211.160(b)(4) with no limits set for accuracy and precision.

Related sections

Related terms

Real inspection findings

Findings from regulators' inspection documents in which this term appears.

1. Did not record chromatography column temperature information for specificity, limit of quantification, limit of detection, linearity, accuracy, precision, intermediate precision, and stability testing; d.

   FDA · FDA Warning Letter · 2024-10-22

2. The calibration of instruments is not done at suitable intervals with provisions for remedial action in the event accuracy and/or precision limit:s are not met.

   FDA · FDA 483 · 2022-11-28

3. The calibration of instruments, apparatus and recording devices is not done at suitable intervals in accordance with an established written program and with provisions for remedial action in the event accuracy and/or precision limits are not met.

   FDA · FDA 483 · 2023-11-15