Quality Control Sample is a well-characterized sample measured alongside production samples to verify that the measurement process remains in control — providing ongoing verification of measurement accuracy and precision during routine operations, separate from calibration.

QC Sample Usage

• Frequency: Run QC samples at regular intervals — every batch, daily, or every N measurements.
• Chart: Plot QC sample results on a control chart — detect drift, shifts, or increased variation.
• Limits: Establish control limits from historical QC data — out-of-control results trigger investigation.
• Multiple Levels: Use QC samples at low, medium, and high values — verify performance across the range.

Why It Matters

• Ongoing Verification: Calibration verifies the gage at one point in time; QC samples provide continuous verification.
• Real Conditions: QC samples are measured under routine conditions — capturing actual operating performance.
• ISO 17025: Accredited labs must use QC samples (or equivalent) to monitor measurement quality continuously.

Quality Control Sample is the daily fitness test — routine measurement of known samples to continuously verify that the measurement system is performing as expected.