Improving Back-Translation with Uncertainty-based Confidence Estimation
Table 1: Comparison of confidence measures.
['Measure', 'BLEU', 'Δ']
We find that using either the translation probabilities outputted by the model (i.e., “PTP”) or the expectation of translation probabilities (i.e., “EXP”) deteriorates the translation quality, which suggests that translation probabilities themselves can not help NMT models better cope with synthetic data. In contrast, using the variance or model uncertainty (i.e., “VAR”) increases translation quality. Combining variance and expectation (i.e., “CEV”) leads to a further improvement. In the following experiments, we use CEV as the default setting.