Which measure describes how closely observed data reflect the true state of the event?

• A. Precision
• B. Reliability
• C. Validity
• D. Accuracy

Answer: (D)

Accuracy describes how close observed data are to the true state of the event. In ABA measurement, you want your data to reflect what actually happened, not just be consistently off, so accuracy captures the closeness to the real value. Precision is about repeatability or how similar measurements are to each other, which can occur even if those measurements are far from the truth. Reliability refers to consistency across time or raters, and validity asks whether the measurement actually assesses the intended construct, not necessarily how close it is to the true state. Therefore, the measure that best describes how closely observed data reflect the true state is accuracy.