Simple techniques work surprisingly well for neural network test prioritization and active learning (replicability study)

Test Input Prioritizers (TIP) for Deep Neural Networks (DNN) are an important technique to handle the typically very large test datasets efficiently, saving computation and labelling costs. This is particularly true for large scale, deployed systems, where inputs observed in production are recorded to serve as potential test or training data for next versions of the system. Feng et. al. propose DeepGini, a very fast and simple TIP and show that it outperforms more elaborate techniques such as neuron- and surprise coverage. In a large-scale study (4 case studies, 8 test datasets, 32’200 trained models) we verify their findings. However, we also find that other comparable or even simpler baselines from the field of uncertainty quantification, such as the predicted softmax likelihood or the entropy of the predicted softmax likelihoods perform equally well as DeepGini