Accuracy vs Precision
How to tell Accuracy and Precision apart when a board question makes them look alike.
Accuracy: closeness to the true value (low systematic error); precision: closeness of repeated measures to each other (low random error).
Side by side
Accuracy means measurements are close to the true value or target center.
Precision means measurements cluster tightly together, regardless of whether they are close to truth.
Accuracy means measurements are close to the true value or target center.
Precision means measurements cluster tightly together, regardless of whether they are close to truth.
The trap
Accuracy is closeness to truth; precision is tight clustering.
The repair move
Before naming the answer, force the stem through the separator: Accuracy is closeness to truth; precision is tight clustering.
Try a free question
CoreAn archer shoots 5 arrows that all hit the bullseye (or very close to it), with individual arrows tightly clustered. The archer's shots are both close to the target center AND close to each other. Which characteristics best describe this performance?
Show answer and explanation
Answer: A. Both accurate and precise. Accuracy = close to true value (validity, low systematic error). Precision = repeated measurements close to each other (reliability, low random error). Both accurate and precise = on target AND tightly clustered. The dartboard analogy is the classic visualization.
Why the other choices are tempting
- B. Accurate but imprecise = scattered around the bullseye (random error high, bias low).
- C. Precise but inaccurate = tightly clustered but off target (bias high, random error low).
- D. Neither = scattered AND off target.
- E. Validity alone doesn't capture both concepts.
Flashcards
Tap a card to flip it.
What clue supports Accuracy?
Choose Accuracy when the stem gives this pattern: Accuracy means measurements are close to the true value or target center.
What clue supports Precision?
Choose Precision when the stem gives this contrasting pattern: Precision means measurements cluster tightly together, regardless of whether they are close to truth.
Quick answers
What is the fastest way to tell Accuracy from Precision?
Accuracy: closeness to the true value (low systematic error); precision: closeness of repeated measures to each other (low random error).
What is the key clue for Accuracy?
Accuracy means measurements are close to the true value or target center.
What is the key clue for Precision?
Precision means measurements cluster tightly together, regardless of whether they are close to truth.
What is the common trap with Accuracy vs Precision?
Accuracy is closeness to truth; precision is tight clustering.