The accuracy of a measurement is determined primarily by how close the measured value is to the true or actual value of the quantity being measured. This closeness is quantitatively evaluated using the percentage error, which is the difference between the measured value and the actual value expressed as a percentage of the actual value. Lower percentage error indicates higher accuracy. Several factors influence measurement accuracy, including:
- Instrument quality and calibration: A well-calibrated instrument traceable to standards ensures higher accuracy.
- Environmental conditions: Temperature, humidity, and pressure variations can alter measurement results, especially for sensitive materials and instruments.
- Surface and sample conditions: Clean and stable surfaces free from dirt or debris reduce measurement errors.
- Human factors: Proper technique and operator skill impact accuracy.
Accuracy differs from precision, where precision relates to the repeatability of measurements, and accuracy involves closeness to the true value. For a measurement system to be considered valid, it must be both precise and accurate. In summary, the accuracy of a measurement is determined by the percentage error, influenced by calibration, environmental conditions, instrument resolution, and operator skill.
