Which statement best defines reliability?

• A. It is the accuracy with which a measure assesses what it intends to measure
• B. It is the generalizability to other settings
• C. It is the magnitude of the relationship with another variable
• D. It is the consistency of results across items or administrations

Answer: (D)

Reliability is about the consistency of a measure. A reliable test yields stable results across items that measure the same construct, across administrations of the test, and across different raters. When a measure is reliable, random error is minimized so observed scores stay similar from one occasion to another or from item to item. This is distinct from validity, which asks whether the test truly measures the intended construct. Generalizability to other settings relates to whether findings hold in different contexts, and the magnitude of the relationship with another variable speaks to validity evidence rather than consistency. Therefore, the description that best defines reliability is the consistency of results across items or administrations.