Effects of Aligned Corpus Quality and Size in Corpus-Based CLIR

摘要

Aligned corpora are often-used resources in CLIR systems. The three qualities of translation corpora that most dramatically affect the performance of a corpus-based CLIR system are: (1) topical nearness to the translated queries, (2) the quality of the alignments, and (3) the size of the corpus. In this paper, the effects of these factors are studied and evaluated. Topics of two different domains (news and genomics) are translated with corpora of varying alignment quality, ranging from a clean parallel corpus to noisier comparable corpora. Also, the sizes of the corpora are varied. The results show that of the three qualities, topical nearness is the most crucial factor, outweighing both other factors. This indicates that noisy comparable corpora should be used as complimentary resources, when parallel corpora are not available for the domain in question.