HOW MUCH NOISE IN A ROLE‐FREE AND LI NK‐FREE CO‐ORDINATE INDEXING SYSTEM?

A study of the number of irrelevant documents retrieved in a co‐ordinate indexing system that does not employ either roles or links. These tests were based on one hundred actual inquiries received in the library and therefore an evaluation of recall efficiency is not included. Over half the inquiries produced no noise, but the mean average percentage noise figure was approximately 33 per cent based on a total average retrieval figure of eighteen documents per search. Details of the size of the indexed collection, methods of indexing, and an analysis of the reasons for the retrieval of irrelevant documents are discussed, thereby providing information officers who are thinking of installing such a system with some evidence on which to base a decision as to whether or not to utilize these devices.