“…The proposed HOR method mainly composes of two stages, called; Fast Rejection (FR) stage and Accurate Rejection (AR) stage as shown in figure 5 . In FR stage, standard division is used as a statistical-based method to quickly reject outliers from the training dataset as possible [ 21 , 22 ]. In AR stage, Binary Gray Wolf Optimization (BGWO) method is used as an optimization technique to accurately remove the rest of outliers in the training data to improve the performance of the classification model [23] .…”