IRE Ineffable concepts in information retrieval chapter Nicholas J. Belkin Butterworth & Company Karen Sparck Jones All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, including photocopying and recording, without the written permission of the copyright holder, application for which should be addressed to the Publishers. Such written permission must also be obtained before any part of this publication is stored in a retrieval system of any nature. 4 Ineffable concepts in information retrieval Nicholas J. Belkin 4.1 Introduction There are a number of concepts (phenomena, entities) which make the testing of information retrieval systems especially difficult. The difficulties they pose arise primarily from their elusive yet ubiquitous nature, since they are difficult to define, either operationally or conceptually, yet they appear central to the information retrieval situation. In my view, that situation is dependent upon the problem of information science, which can be stated as: the effective transfer of desired information from human generator to human user1. This problem is further specified by the information retrieval situation which can be characterized as follows (a) A user, recognizing an information need, presents to an information retrieval mechanism (i.e. a collection of texts, with a set of associated activities) a request, based upon that need, hoping that the information retrieval mechanism will be able to satisfy the need. (b) The task of the information retrieval mechanism is to present the user with the text (or texts) which it judges to be most likely to satisfy the user's information need, based upon the request put to the mechanism. (c) The user examines the text, or some or all of the texts, presented by the mechanism, and her/his need is satisfied completely or partially or not at all. The user's judgement as to the contribution of each text in satisfying the need establishes the usefulness or relevance of that text to the need. Thus the fundamental issues with which information retrieval is concerned must include: information need; desire; information; aboutness or meaning; satisfaction (including relevance); and effectiveness (of information). These issues or concepts attain their importance because of the way in which information retrieval systems attempt to solve the problem of information science, and in that context can be roughly categorized as follows. 44