Concepts
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The lesson that is to be learnt is that should new research get underway it will be very important to have a suitable data base ready
...Information retrieval systems are likely to play an every increasing part in the community
...One major recent development is that computers and data bases are becoming linked into A study recommending the provision of such an experimental test bed has recently been completed,see Sparck Jones and van Rijsbergen,Information retrieval test collections,Journal of Documentation,32,59 75 1976
...networks
...By extending the user population to include the non specialist,it is likely that an IR system will be expected to provide not just a citation,but a display of the text,or part of it,and perhaps answer simple questions about the retrieved documents
...To bring all this about the document retrieval system will have to be interfaced and integrated with data retrieval systems,to give access to facts related to those in the documents
...Another example can be found in the context of computer aided instruction,where it is clearly a good idea to give a student access to a document retrieval system which will provide him with further reading on a topic of his immediate interest
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Sparck Jones has carried on this work using measures of association between keywords based on their frequency of co occurrence that is,the frequency with which any two keywords occur together in the same document
...The term information structure for want of better words covers specifically a logical organisation of information,such as document representatives,for the purpose of information retrieval
...The organisation of these files is produced by an automatic classification method
...Evaluation of retrieval systems has proved extremely difficult
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are linked into a network in which any given link between two items exists because it satisfies some condition on the attributes of those items,for example,they share an attribute
...The whole field of data base structures is still very much in a state of flux
...Lurking in the background of any discussion of file structures nowadays is always the question whether data base technology will overtake all
...A language for describing file structures Like all subjects in computer science the terminology of file structures has evolved higgledy piggledy without much concern for consistency,ambiguity,or whether it was possible to make the kind of distinctions that were important
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frequency of occurrence and co occurrence of index terms in the relevant and non relevant documents
...Chapter 7:Evaluation here I give a traditional view of the measurement of effectiveness followed by an explanation of some of the more promising attempts at improving the art
...Chapter 8:The Future contains some speculation about the future of IR and tries to pinpoint some areas of research where further work is desperately needed
...Information retrieval Since the 1940 s the problem of information storage and retrieval has attracted increasing attention
...In principle,information storage and retrieval is simple
...When high speed computers became available for non numerical work,many thought that a computer would be able to read an entire document collection to extract the relevant documents
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automatic and interactive retrieval system?Studies to gauge this are going on but results are hard to interpret
...It should be apparent now that in evaluating an information retrieval system we are mainly concerned with providing data so that users can make a decision as to 1 whether they want such a system social question and 2 whether it will be worth it
...The second question what to evaluate?boils down to what can we measure that will reflect the ability of the system to satisfy the user
...1 The coverage of the collection,that is,the extent to which the system includes relevant matter;2 the time lag,that is,the average interval between the time the search request is made and the time an answer is given;3 the form of presentation of the output;4 the effort involved on the part of the user in obtaining answers to his search requests;5 the recall of the system,that is,the proportion of relevant material actually retrieved in answer to a search request;6 the precision of the system,that is,the proportion of retrieved material that is actually relevant
...It is claimed that 1 4 are readily assessed
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systems store only a representation of the document or query which means that the text of a document is lost once it has been processed for the purpose of generating its representation
...When the retrieval system is on line,it is possible for the user to change his request during one search session in the light of a sample retrieval,thereby,it is hoped,improving the subsequent retrieval run
...Secondly,the processor,that part of the retrieval system concerned with the retrieval process
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behaviour of any one of the components depends in only an aggregate way on the behaviour of the other components
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...On the file structure chosen and the way it is used depends the efficiency of an information retrieval system
...Inverted files have been rather popular in IR systems
...There are many more problems in this area which are of interest to IR systems
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...So far fairly simple search strategies have been tried
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