Rank-consistent Ordinal Regression for Neural Networks

Extraordinary progress has been made towards developing neural network architectures for classification tasks. However, commonly used loss functions such as the multi-category cross entropy loss are inadequate for ranking and ordinal regression problems. Hence, approaches that utilize neural networks for ordinal regression tasks transform ordinal target variables series of binary classification tasks but suffer from inconsistencies among the different binary classifiers. Thus, we propose a new framework (Consistent Rank Logits, CORAL) with theoretical guarantees for rank-monotonicity and consistent confidence scores. Through parameter sharing, our framework also benefits from lower training complexity and can easily be implemented to extend conventional convolutional neural network classifiers for ordinal regression tasks. Furthermore, the empirical evaluation of our method on a range of face image datasets for age prediction shows a substantial improvement compared to the current state-of-the-art ordinal regression method.