Accuracy vs Precision
Side by side comparison: how they work, where each fits, and which to choose.
Quick answer: Accuracy is closeness to the true value; precision is closeness of repeated readings to each other. Calibration fixes accuracy offsets but not poor precision.
Accuracy vs Precision: Comparison Table
| Aspect | Accuracy | Precision |
|---|---|---|
| Describes | Bias from the true value | Spread of results |
| Measured by | Error against a reference | Repeatability, standard deviation |
| Improved by | Calibration and adjustment | Better instrument, less noise |
| Example | Mean reads 10.00 when true is 10.00 | Readings all within ± 0.01 |
Choose Accuracy when
- Billing, safety limits, quality release
Choose Precision when
- Control loops and trend detection
Key Differences Explained
A darts analogy helps: tight groups far from the centre are precise but not accurate; scattered darts around the centre are accurate on average but not precise.
Instrument specifications usually combine both into one accuracy figure.
Related Glossary Terms
Free Calculators
Frequently Asked Questions
What is the difference between Accuracy and Precision?
Accuracy is closeness to the true value; precision is closeness of repeated readings to each other. Calibration fixes accuracy offsets but not poor precision.
Can an instrument be precise but inaccurate?
Yes, with a constant bias.
Is resolution the same as precision?
No, resolution is the smallest change the display or converter shows.
Which matters for control?
Precision and repeatability.
Learn more on the blog
Instrumentation calibration and troubleshooting guide
A practical guide on instrumentationblog.in that goes deeper into this topic with field examples.
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