Which term describes the repeatability of a measurement under the same conditions?

• A. Validity
• B. Reliability
• C. Sensitivity
• D. Specificity

Answer: (B)

Reliability is about consistency in measurement. When you perform the same measurement under the same conditions and get the same result each time, the instrument and procedure are considered reliable. This repeatability is what reliability captures—the idea that results are stable and not due to random variation.

However, reliability alone doesn’t tell you whether you’re measuring what you intend to measure. That’s validity, which is about accuracy and whether the measurement reflects the true construct. It’s possible to have a measurement that is consistently wrong because of a systematic bias—reliable but not valid.

Sensitivity and specificity describe a diagnostic test’s performance in correctly identifying true positives and true negatives. They’re about classification accuracy, not about whether results are repeatable across repeated trials. So the feature described—repeatability under the same conditions—fits reliability best.