Which statement best describes the purpose of running controls at regular intervals?

• A. To extend reagent shelf life.
• B. To verify assay performance and detect drift.
• C. To eliminate the need for charts.
• D. To train new personnel only.

Answer: (B)

Running controls at regular intervals checks that the entire testing process is performing correctly, including reagents, instruments, and technique. By measuring control materials with known values, you confirm that the assay gives accurate and consistent results in practice, not just in theory. If a control result falls outside its established range or shows a gradual trend over time, that signals drift or a potential problem, prompting investigation and corrective actions before patient results are reported. This is why controls are used: to verify assay performance and detect drift, keeping the lab’s results reliable. It isn’t about extending reagent shelf life, it doesn’t eliminate charting, and it’s not solely for training new staff.