2. Measurement Process Characterization
2.3. Calibration

2.3.1.

Issues in calibration

Calibration reduces bias

Calibration is a measurement process that assigns values to the property of an artifact or to the response of an instrument relative to reference standards or to a designated measurement process. The purpose of calibration is to eliminate or reduce bias in the user's measurement system relative to the reference base.

Artifact & instrument calibration

The calibration procedure compares an "unknown" or test item(s) or instrument with reference standards according to a specific algorithm. Two general types of calibration are considered in this Handbook:

• artifact calibration at a single point
• instrument calibration over a regime

Types of calibration not discussed

The procedures in this Handbook are appropriate for calibrations at secondary or lower levels of the traceability chain where reference standards for the unit already exist. Calibration from first principles of physics and reciprocity calibration are not discussed.