Identify the Formula Used to Calculate the Root Mean Square $=\sqrt{\frac{\sum_{t=1}^{n}\left|A_{t}-F_{t}\right|}{n}}$

Multiple Choice

Identify the formula used to calculate the root mean square error over a range of forecasted values, if the actual value of the time series at time t and the forecast value for time t are denoted by At and Ft respectively.

A) RMSE $=\sqrt{\frac{\sum_{t=1}^{n}\left|A_{t}-F_{t}\right|}{n}}$

B) RMSE $=\sqrt{\frac{\sum_{t=1}^{n} \sqrt{\left|A_{t}-F_{t}\right|}}{n}}$

C) RMSE $=\sqrt{\frac{\sum_{t=1}^{n}\left(\lambda t-F_{t}\right) ^{2}}{n}}$

D) RMSE $=\sqrt{\frac{\sum_{t=1}^{n}\left|\frac{A_{t}+F_{t}}{2}\right|}{n}}$