On Measuring Context Utilization in Document-Level MT Systems
Wafaa Mohammed Vlad Niculae
Document-level translation models are usually evaluated using general metrics
such as BLEU, which are not informative about the benefits of context. Current
work on context-aware evaluation, such as contrastive methods, only measure
translation accuracy on words that need context for disambiguation. Such
measures cannot reveal whether the translation model uses the correct
supporting context. We propose to complement accuracy-based evaluation with
measures of context utilization. We find that perturbation-based analysis
(comparing models' performance when provided with correct versus random
context) is an effective measure of overall context utilization. For a
finer-grained phenomenon-specific evaluation, we propose to measure how much
the supporting context contributes to handling context-dependent discourse
phenomena. We show that automatically-annotated supporting context gives
similar conclusions to human-annotated context and can be used as alternative
for cases where human annotations are not available. Finally, we highlight the
importance of using discourse-rich datasets when assessing context utilization.