When comparing how well different algorithms forecast time series, researchers use an average value of the ratio |x− y| (|x|+ |y|)/2 , known as the Symmetric Mean Absolute Percentage Error (SMAPE). In this paper, we provide a system-motivated explanation for this formula. We also explain how this formula explains the use of geometric mean to combine different forecasts.

The predictive accuracy of various econometric models, including random walks, vector autoregressive and vector error-correction models, are investigated using daily futures prices of 4 commodities (the S&P500 index, treasury bonds, gold and crude oil). All models are estimated using a rolling window approach, and evaluated by both in-sample and out-of-sample performance measures. The criteria ...

in this study two intelligent systems, based on adaptive neuro-fuzzy inference systems (anfis) and artificial neural networks (anns) of forecasting municipal solid wastes (msw) generation has been proposed. anfis and anns as an intelligent tool compared with together was used to monthly prediction of msw generated in tehran. monthly amount of solid wastes (sw), total monthly precipitation, mont...

Abstract. The root-mean-squared error (RMSE) and mean absolute (MAE) are widely used metrics for evaluating models. Yet, there remains enduring confusion over their use, such that a standard practice is to present both, leaving it the reader decide which more relevant. In recent reprise 200-year debate Willmott Matsuura (2005) Chai Draxler (2014) give arguments favoring one metric or other. How...

Horizontal directional drilling is usually used in drilling engineering. In a variety of conditions, it is necessary to predict the torque required for performing the drilling operation. Nevertheless, there is presently not a convenient method available to accomplish this task. In order to overcome this difficulty, the current work aims at predicting the required rotational torque (RT) to opera...

Purpose: Proprioception is a part of the somatosensory system responsible for sending information to the central nervous system to monitor the status of various body parts relative to each another. One of the main causes of impaired proprioception is fatigue. In the following study, the effects of fatigue on quadriceps muscle and hence on knee proprioception in healthy subjects was studied.&nbs...