Measurement Error
Definition
The discrepancy between a recorded value and the true value of the property being measured. Arises from instrument calibration limits, analyst technique, environmental conditions, and procedure-specific factors. Distinct from natural variability in the material itself.
- Sources
- Instrument calibration, analyst technique, environment
- Distinct from
- Natural sample-to-sample variability
- Managed via
- Calibration, controls, and uncertainty budgets
Common questions
How do labs distinguish measurement error from real material variability?+
Labs run replicate measurements on the same sample under fixed conditions to isolate measurement error, then compare that spread against the variation seen across different samples of the same material, which reflects genuine heterogeneity rather than instrument or analyst noise.
Why does measurement error matter for reporting a quantitative result in court?+
A single reported value without its measurement uncertainty overstates precision, so accredited labs report results with an uncertainty interval derived from documented error sources, which lets a court judge whether two values are meaningfully different.
Related terms
- Accuracy
- The degree to which a measured value agrees with the accepted true or reference value of the quantity. A biased instrument can...
- Between-Class Variability
- The spread of measurements between items from different sources or categories. A forensic method is most discriminating when between-class variability is large...
- Precision
- The degree to which repeated measurements of the same specimen under the same conditions agree with each other. Quantified by the standard...
- Repeatability
- The agreement between successive measurements of the same specimen made by the same analyst, on the same instrument, in the same laboratory,...
- Within-Class Variability
- The natural spread of measurements among items that share a common source, class, or category. For example, the range of refractive index...