RMSE (Root Mean Squared Error)

Description

Root Mean Square Error (RMSE) is the standard deviation of the residuals (prediction errors). Residuals are a measure of how far from the regression line data points are; RMSE is a measure of how spread out these residuals are. In other words, it tells you how concentrated the data is around the line of best fit.

Formula

Where f = forecasts (expected values or unknown results) and o = observed values (known results).

Example