RMSE

169. RMSE

square root of the average squared differences between predicted ( ${\hat{𝑦}}_{𝑖}$ ) and actual ( $𝑦_{𝑖}$ ) values

RMSE = \sqrt{\frac{1}{𝑛} \sum_{𝑖 = 1}^{𝑛} {(𝑦_{𝑖} - {\hat{𝑦}}_{𝑖})}^{2}}