quality control sample

**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.