# Dictionary:Rms error (σ)

The square root of the average of the squares of the differences between a series of ${\displaystyle n}$ measurements ${\displaystyle m_{i}}$, and their mean ${\displaystyle {\bar {m}}}$. The rms error
${\displaystyle \sigma ={\sqrt {\frac {\sum (m_{i}-{\bar {m}})^{2}}{n}}}}$;