What is the difference between 'precision' and 'accuracy' in data reporting?

• A. Precision refers to the level of detail or variability in measurements; accuracy refers to closeness to the true value
• B. Precision refers to closeness to the true value; accuracy refers to the level of detail or variability in measurements
• C. They are the same
• D. Precision measures bias; accuracy measures precision

Answer: (A)

Think about what each term says about your data: precision is about how consistent repeated measurements are, while accuracy is about how close those measurements are to the true value. If you measure the same object many times and the results cluster tightly together, you have high precision. If those clustered results also sit right on the true value, you have high accuracy. But you can have high precision with low accuracy if the measurements are all very close to each other but far from the true value (a systematic bias). Conversely, you can have high accuracy with low precision if the measurements are spread out but their average is near the true value. In short, precision = consistency/variability; accuracy = closeness to the true value.