Which statement best defines reliability and validity in psychological measurement?

• A. Reliability is consistency; validity is whether the measure assesses what it intends to.
• B. Validity is about the population; reliability is about the sample.
• C. Reliability is accuracy; validity is speed.
• D. Reliability and validity are the same thing.

Answer: (A)

Reliability means the measurement gives consistent results across repeated use, items, or raters. Validity is about whether the measurement actually captures the thing it’s meant to measure. The statement that reliability is consistency and validity is about whether the measure assesses what it intends to measure is the best fit because it keeps the definitions distinct and focused on what the tool does across time and in relation to the target construct.

For context, you can imagine a scale that yields the same number every time—that’s reliable. But if that number doesn’t reflect the true weight it’s supposed to measure, it isn’t valid. Conversely, a test could be valid in measuring the intended trait but unreliable if it gives wildly different results across attempts. The other options mix up concepts or misstate what reliability and validity refer to (population vs sample, speed, or being the same thing), so they don’t fit as well.