Efficient Estimation of Influence of a Training Instance

Understanding the influence of a training instance on a machine-learning model is important for interpreting the behavior of the model. However, it has been difficult and inefficient to evaluate the influence, considering how the prediction of a model would be changed if a training instance were not used. This prevents the application of influence estimation in neural networks with a large number of parameters. In this paper, we propose an efficient method for estimating the influence for neural networks. The method is inspired by dropout, which zero-masks a sub-network and prevents the sub-network from learning each training instance. By switching between dropout masks, we can use sub-networks that learned or did not learn each training instance and estimate its influence based on the difference between the sub-networks. Through experiments with BERT and VGGNet on classification datasets, it was demonstrated that the proposed method can enhance the interpretability of error predictions. Quantitative evaluations were also performed by analyzing learning curves of sub-networks and applying the method to data filtering.