180 INFORMATION RETRIEVAL SYSTEMS

Implicit use orientation is the attitude taken by a subject about the intended use of a document. Implicit use orientations demonstrably affect the relevance attributed to a document. The methodological shortcomings of information retrieval are apparent in the work on 'relevance'. The effectiveness of an information retrieval system relies heavily on the notion of a 'relevant set of documents'. The problem is that relevance judgements cannot be shown to be insensitive to variables extraneous to the document requirement relationship.