Precision
Definition
How close repeated measurements of the same sample fall to each other, reported as a relative standard deviation. Repeatability is precision within one run, intermediate precision across days and analysts in one laboratory.
In more detail
Precision describes scatter rather than correctness, and is reported as a relative standard deviation across replicates. It comes in widening circles: repeatability within a single run, intermediate precision across different days and analysts in one laboratory, and reproducibility between laboratories.
Which one is quoted changes what the number means. A tight repeatability figure says the instrument was stable that morning. It says very little about whether a second laboratory handed the same vial would report the same purity, which is the question a buyer sending material for independent testing is actually asking.
Where this term comes up
Entries whose definition mentions Precision.
What this means for research sourcing
Purity and identity verification are central to research reproducibility. Every Volta compound ships with >99% HPLC-verified purity and a certificate of analysis.
Related Terms in Quality
Reproducibility
Agreement between results for the same material measured in different laboratories. It is the widest form of precision and the one that matters when a buyer sends a vial for independent testing.
Calibration
Relating an instrument's signal to known quantities of a reference standard, so a peak area can be read as a concentration. An uncalibrated instrument still produces numbers; they just do not mean anything outside that run.
Method Validation
The documented exercise proving a method does what it claims: specificity, linearity, accuracy, precision, range, and the limits at which it stops working. Validation is done once for the method, not once per sample.
Method Verification
Demonstrating that an already-validated method performs as expected in the laboratory now using it. A compendial method arrives validated; a laboratory still has to show its own instruments and analysts reproduce it.
System Suitability
Checks run immediately before samples to prove the instrument is fit to measure anything that day: peak shape, resolution between critical pairs, and repeatability of replicate injections. A failed system suitability invalidates the run rather than the material.
Analytical Selectivity
A method's ability to measure the intended analyte without interference from impurities, excipients or degradation products. A purity figure from a method that cannot separate a close-eluting impurity overstates purity.
Orthogonal Method
A second method resting on a different physical principle, used to test a result rather than repeat it. Running reversed-phase HPLC and then mass spectrometry is orthogonal; running the same HPLC method twice is not.
Out of Specification (OOS)
A result that falls outside an acceptance criterion. It triggers an investigation into whether the measurement or the material is at fault, and an OOS cannot be resolved by simply retesting until a passing number appears.