Which of the following is NOT a type of error measurement used in forecasting?

The correct answer identifies that Weighted Average Error (WAE) is not a standard type of error measurement used in forecasting. In forecasting, error measurements play a crucial role in assessing the accuracy of predicted values against actual values.

Mean Absolute Error (MAE) quantifies the average magnitude of errors in a set of predictions, without considering their direction. It is calculated as the average of the absolute differences between predicted and actual values, providing a straightforward interpretation of error magnitude.

Root Mean Square Error (RMSE) measures the square root of the average of squared differences between prediction and actual observation. It gives more weight to larger errors, making it particularly useful when large errors are particularly undesirable.

Mean Absolute Percentage Error (MAPE) expresses accuracy as a percentage and is calculated as the average absolute percent error for each time period. This measure is useful for comparing the forecast accuracy across different datasets.

In contrast, Weighted Average Error (WAE) is not a recognized standard in forecasting methodologies in the same way as the other three metrics. While it may conceptually refer to some weighted consideration of errors, it does not have a specific definition or standard usage in the context of forecasting that is widely accepted. Thus, this option does not fit within conventional forecasting error measurements