Random Error
Unpredictable, non-repeatable fluctuations in experimental measurements that occur with equal probability in either direction.
Governing formula
Standard Error = σ / √N
SI unit
Various
In depth
Random errors stem from ambient thermal noise, mechanical vibration, human reaction variability, or electrical fluctuations. Their impact on the calculated mean decreases as 1/√N when averaging N independent measurements.
Examples in the real world
Slight reaction time variations when pressing a manual stopwatch, or electrical noise in a sensitive voltmeter reading.