In Quality Assurance terminology, how is drift defined?

• A. A sudden change in measurement values.
• B. A gradual change in measured values over time.
• C. An abrupt calibration failure.
• D. A fixed error that occurs in measurements.

Answer: (B)

Drift in Quality Assurance terminology refers to a gradual change in measured values over time. This phenomenon occurs when the performance of an instrument slowly changes, often leading to inaccuracies in measurements if not identified and corrected.

Drift can result from various factors, such as environmental influences, instrument wear, or fluctuation in the operating conditions. The significance of understanding drift lies in its potential to undermine the reliability of data collected over time, making it crucial for operators to regularly monitor and assess their equipment.

In contrast to other definitions provided in the options, which describe more immediate issues or fixed errors, drift emphasizes a slow and ongoing variation that underlines the importance of consistent quality control practices and regular recalibration of instruments to ensure accurate and reliable measurements in bone densitometry or any measurement context.