Utilizing lexical data from a Web-derivedcorpus to expand productive collocationknowledge

Collocations are of great importance for second language learners, and a learner’s knowledgeof them plays a key role in producing language fluently (Nation, 2001: 323). In this article wedescribe and evaluate an innovative system that uses a Web-derived corpus and digital librarysoftware to produce a vast concordance and present it in a way that helps students usecollocations more effectively in their writing. Instead of live search we use an off-line corpus ofshort sequences of words, along with their frequencies. They are preprocessed, filtered, andorganized into a searchable digital library collection containing 380 million five-wordsequences drawn from a vocabulary of 145,000 words. Although the phrases are short, learnerscan browse more extended contexts because the system automatically locates samplesentences that contain them, either on the Web or in the British National Corpus. Twoevaluations were conducted: an expert user tested the system to see if it could generate suitablealternatives for given text fragments, and students used it for a particular exercise. Bothsuggest that, even within the constraints of a limited study, the system could and did helpstudents improve their writing