DIFERENCIA ENTRE EXACTITUD Y PRECISIÓN | METROLOGÍA

Main Ideas

• Accuracy describes how close a measurement is to the true or reference value.
• Precision describes how consistent or repeatable measurements are when the same quantity is measured repeatedly. Results that vary widely are imprecise.
• An instrument can be:
  • Accurate and precise: Measurements are both close to the reference value and consistent.
  • Precise but inaccurate: Measurements are consistent but systematically off from the reference value.
  • Inaccurate and imprecise: Measurements are inconsistent and generally not close to the reference value.

Examples

• Caliper: If a part’s true size is 25 mm and repeated readings are around 25.01–25.03 mm, the results are close to the reference and consistent. The instrument is both accurate and precise.
• If another caliper repeatedly reads about 25.50 mm for that same part, it is precise but inaccurate: it gives consistent results, but they are biased away from the true value.
• Watch: A watch that gains two minutes every day is consistent in how it drifts, so it is precise but not accurate. A watch that runs erratically is both imprecise and inaccurate.

Metrology and Improvement

The ideal instrument is both accurate and precise.

Repeatability is associated with factors such as instrument design, materials, the measurement system, sensor type, and internal stability.

Calibration compares an instrument’s readings with a reference standard. Adjustments or corrections, documented in a certificate, can bring its measurements closer to the reference value.

Terminology note: The subtitles occasionally use “accurate” where the explanation calls for “precise”—especially when describing repeated, consistent measurements that are not close to the true value. The standard distinction is: precision = consistency; accuracy = closeness to the true value.

Speaker/Source

One unnamed narrator or presenter explains the concepts. No other speakers or sources are identified.