Definitions
Accuracy describes how close a measured value is to the true or accepted value of the quantity being measured. Precision describes how close repeated measurements are to one another, independent of how close they are to the true value.
In practice, a method can be precise without being accurate (tight cluster, wrong target), accurate without being precise (centered scatter, no reproducibility), both, or neither. Reference materials are the tool that lets a laboratory diagnose which case it is in.
Why the distinction matters
Analytical decisions — instrument calibration, method validation, out-of-specification investigations — depend on separating systematic error (bias) from random error (variance). Accuracy captures systematic error; precision captures random error. Confusing the two leads to over-trusting reproducible bias or dismissing valid data as noise.
The role of reference materials
A characterized reference material provides a known target value. Measuring it repeatedly under controlled conditions produces the two data points a laboratory needs: the mean (accuracy relative to the reference value) and the spread (precision as standard deviation, RSD, or coefficient of variation).
In general, reference materials with documented identity, purity, and lot-level analytical release — for example, per-lot HPLC purity, mass spectrometry identity confirmation, and Certificates of Analysis — allow this comparison to be traceable and defensible. This describes the category broadly and is not a claim about Carbon Standard materials.
Practical guidance
- Report accuracy and precision separately; a single "error" value hides the diagnostic signal.
- Qualify each reference material by lot — different lots may have different characterization data.
- Use replicate measurements against a reference standard as the primary check for method drift over time.
- Retain Certificates of Analysis alongside raw data so historical measurements can be re-interpreted if a reference value is revised.
Research context
This guide is educational and provided for scientific reference. Nothing on this page is medical, therapeutic, diagnostic, or dosing advice. All Carbon Standard materials are Research Use Only.