Search (144 results, page 8 of 8)

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Abstract

Very interesting experimental work was done by Douglas Foskett and other British classificationists during the fifteen-year period following the end of World War II. The research was effective in demonstrating that it was possible to make very sophisticated classification systems for virtually any subject-systems suitable for experts and for the general user needing a detailed subject classification. The success of these special systems led to consideration of the possibility of putting them together to form a new general classification system. To do such a thing would require a general, overall framework of some kind, since systems limited to a special subject are easier to construct because one does not have to worry about including all of the pertinent facets needed for a general system. Individual subject classifications do not automatically coalesce into a general pattern. For example, what is central to one special classification might be fringe in another or in several others. Fringe terminologies may not coincide in terms of logical relationships. Homographs and homonyms may not rear their ugly heads until attempts at merger are made. Foskett points out that even identifying a thing in terms of a noun or verb involves different assumptions in approach. For these and other reasons, it made sense to look for existing work in fields where the necessary framework already existed. Foskett found the rudiments of such a system in a number of writings, culminating in a logical system called "integrative levels" suggested by James K. Feibleman (q.v.). This system consists of a set of advancing conceptual levels relating to the apparent organization of nature. These levels are irreversible in that if one once reached a certain level there was no going back. Foskett points out that with higher levels and greater complexity in structure the analysis needed to establish valid levels becomes much more difficult, especially as Feibleman stipulates that a higher level must not be reducible to a lower one. (That is, one cannot put Humpty Dumpty together again.) Foskett is optimistic to the extent of suggesting that references from level to level be made upwards, with inductive reasoning, a system used by Derek Austin (q.v.) for making reference structures in PRECIS. Though the method of integrative levels so far has not been used successfully with the byproducts of human social behavior and thought, so much has been learned about these areas during the past twenty years that Foskett may yet be correct in his optimism. Foskett's name has Jong been associated with classification in the social sciences. As with many of the British classificationists included in this book, he has been a member of the Classification Research Group for about forty years. Like the others, he continues to contribute to the field.

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Abstract

The selection in this reader by R. M. Needham and K. Sparck Jones reports an early approach to automatic classification that was taken in England. The following selection reviews various approaches that were being pursued in the United States at about the same time. It then discusses a particular approach initiated in the early 1960s by Harold Borko, at that time Head of the Language Processing and Retrieval Research Staff at the System Development Corporation, Santa Monica, California and, since 1966, a member of the faculty at the Graduate School of Library and Information Science, University of California, Los Angeles. As was described earlier, there are two steps in automatic classification, the first being to identify pairs of terms that are similar by virtue of co-occurring as index terms in the same documents, and the second being to form equivalence classes of intersubstitutable terms. To compute similarities, Borko and his associates used a standard correlation formula; to derive classification categories, where Needham and Sparck Jones used clumping, the Borko team used the statistical technique of factor analysis. The fact that documents can be classified automatically, and in any number of ways, is worthy of passing notice. Worthy of serious attention would be a demonstra tion that a computer-based classification system was effective in the organization and retrieval of documents. One reason for the inclusion of the following selection in the reader is that it addresses the question of evaluation. To evaluate the effectiveness of their automatically derived classification, Borko and his team asked three questions. The first was Is the classification reliable? in other words, could the categories derived from one sample of texts be used to classify other texts? Reliability was assessed by a case-study comparison of the classes derived from three different samples of abstracts. The notso-surprising conclusion reached was that automatically derived classes were reliable only to the extent that the sample from which they were derived was representative of the total document collection. The second evaluation question asked whether the classification was reasonable, in the sense of adequately describing the content of the document collection. The answer was sought by comparing the automatically derived categories with categories in a related classification system that was manually constructed. Here the conclusion was that the automatic method yielded categories that fairly accurately reflected the major area of interest in the sample collection of texts; however, since there were only eleven such categories and they were quite broad, they could not be regarded as suitable for use in a university or any large general library. The third evaluation question asked whether automatic classification was accurate, in the sense of producing results similar to those obtainabie by human cIassifiers. When using human classification as a criterion, automatic classification was found to be 50 percent accurate.

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Footnote

Original in: Information retrieval today: papers presented at an Institute conducted by the Library School and the Center for Continuation Study, University of Minnesota, Sept. 19-22, 1962. Ed. by Wesley Simonton. Minneapolis, Minn.: The Center, 1963. S.21-36.