Ensemble-based Transfer Learning for Low-resource Machine Translation Quality Estimation
This work addresses the problem of machine translation quality estimation for low-resource languages, which is incremental as it builds on existing methods with transfer learning.
The paper tackled the challenge of predicting machine translation quality scores for low-resource languages with scarce training data by proposing an ensemble-based transfer learning model, achieving a Pearson's correlation of 0.298, which is 2.54 times higher than baselines.
Quality Estimation (QE) of Machine Translation (MT) is a task to estimate the quality scores for given translation outputs from an unknown MT system. However, QE scores for low-resource languages are usually intractable and hard to collect. In this paper, we focus on the Sentence-Level QE Shared Task of the Fifth Conference on Machine Translation (WMT20), but in a more challenging setting. We aim to predict QE scores of given translation outputs when barely none of QE scores of that paired languages are given during training. We propose an ensemble-based predictor-estimator QE model with transfer learning to overcome such QE data scarcity challenge by leveraging QE scores from other miscellaneous languages and translation results of targeted languages. Based on the evaluation results, we provide a detailed analysis of how each of our extension affects QE models on the reliability and the generalization ability to perform transfer learning under multilingual tasks. Finally, we achieve the best performance on the ensemble model combining the models pretrained by individual languages as well as different levels of parallel trained corpus with a Pearson's correlation of 0.298, which is 2.54 times higher than baselines.