Deep neural networks achieve remarkable performances on a wide range of tasks with the aid of large-scale labeled datasets. However, large-scale annotations are time-consuming and labor-exhaustive to obtain on realistic tasks. To mitigate the requirement for labeled data, self-training is widely used in both academia and industry by pseudo labeling on readily-available unlabeled data. Despite its popularity, pseudo labeling is well-believed to be unreliable and often leads to training instability. Our experimental studies further reveal that the performance of self-training is biased due to data sampling, pre-trained models, and training strategies, especially the inappropriate utilization of pseudo labels. To this end, we propose Debiased, in which the generation and utilization of pseudo labels are decoupled by two independent heads. To further improve the quality of pseudo labels, we introduce a worst-case estimation of pseudo labeling and seamlessly optimize the representations to avoid the worst-case. Extensive experiments justify that the proposed Debiased not only yields an average improvement of $14.4$\% against state-of-the-art algorithms on $11$ tasks (covering generic object recognition, fine-grained object recognition, texture classification, and scene classification) but also helps stabilize training and balance performance across classes.

在半监督学习中，为了减少标记数据的需求，经常使用自我训练来分配伪标签。然而，由于自我训练中可能会出现错误的伪标签，从而导致训练不稳定，因此提出了一种去偏差的自我训练方法，它使用两个参数独立的分类器头来分离伪标签的生成和利用，并通过对抗优化表征来改善伪标签的质量，从而稳定训练并提高性能。

去偏自我训练用于半监督学习