Final answer:
Assaying materials of known concentration to verify the calibration of lab instruments or test systems, as required by CLIA law, is known as calibration verification. It is crucial for ensuring laboratory test accuracy and reliability over time.
Step-by-step explanation:
The process of assaying materials of known concentration in the same manner as patient samples to substantiate the calibration of an instrument or test system throughout the reportable range for patient test results is known as calibration verification. This is an essential component of maintaining the accuracy and reliability of laboratory tests under the Clinical Laboratory Improvement Amendments (CLIA) law. Calibration verification helps in ensuring that the laboratory test system is providing accurate results over time and across the entire range of expected patient values.