Measurement Errors and Accuracy

• Accuracy — closeness to the true value.
• Precision — repeatability of readings.
• Resolution — the smallest detectable change.

Error types: gross (human mistakes), systematic (instrument calibration, loading, environmental effects) and random (noise, reduced by averaging).

$\text{error (\%)} = \frac{\text{measured} - \text{true}}{\text{true}} \times 100$

Analog instruments specify accuracy as a percentage of full scale — so read near the top of the range. Digital meters specify ±(% of reading + counts).