Search (5 results, page 1 of 1)

0.026081776 = product of:
  0.13040888 = sum of:
    0.13040888 = weight(_text_:index in 577) [ClassicSimilarity], result of:
      0.13040888 = score(doc=577,freq=2.0), product of:
        0.2250935 = queryWeight, product of:
          4.369764 = idf(docFreq=1520, maxDocs=44218)
          0.051511593 = queryNorm
        0.5793543 = fieldWeight in 577, product of:
          1.4142135 = tf(freq=2.0), with freq of:
            2.0 = termFreq=2.0
          4.369764 = idf(docFreq=1520, maxDocs=44218)
          0.09375 = fieldNorm(doc=577)
  0.2 = coord(1/5)

0.026081776 = product of:
  0.13040888 = sum of:
    0.13040888 = weight(_text_:index in 1957) [ClassicSimilarity], result of:
      0.13040888 = score(doc=1957,freq=2.0), product of:
        0.2250935 = queryWeight, product of:
          4.369764 = idf(docFreq=1520, maxDocs=44218)
          0.051511593 = queryNorm
        0.5793543 = fieldWeight in 1957, product of:
          1.4142135 = tf(freq=2.0), with freq of:
            2.0 = termFreq=2.0
          4.369764 = idf(docFreq=1520, maxDocs=44218)
          0.09375 = fieldNorm(doc=1957)
  0.2 = coord(1/5)

0.01738785 = product of:
  0.08693925 = sum of:
    0.08693925 = weight(_text_:index in 576) [ClassicSimilarity], result of:
      0.08693925 = score(doc=576,freq=2.0), product of:
        0.2250935 = queryWeight, product of:
          4.369764 = idf(docFreq=1520, maxDocs=44218)
          0.051511593 = queryNorm
        0.3862362 = fieldWeight in 576, product of:
          1.4142135 = tf(freq=2.0), with freq of:
            2.0 = termFreq=2.0
          4.369764 = idf(docFreq=1520, maxDocs=44218)
          0.0625 = fieldNorm(doc=576)
  0.2 = coord(1/5)

0.01738785 = product of:
  0.08693925 = sum of:
    0.08693925 = weight(_text_:index in 3643) [ClassicSimilarity], result of:
      0.08693925 = score(doc=3643,freq=8.0), product of:
        0.2250935 = queryWeight, product of:
          4.369764 = idf(docFreq=1520, maxDocs=44218)
          0.051511593 = queryNorm
        0.3862362 = fieldWeight in 3643, product of:
          2.828427 = tf(freq=8.0), with freq of:
            8.0 = termFreq=8.0
          4.369764 = idf(docFreq=1520, maxDocs=44218)
          0.03125 = fieldNorm(doc=3643)
  0.2 = coord(1/5)

Abstract

A landmark event in the twentieth-century development of subject analysis theory was a retrieval experiment, begun in 1957, by Cyril Cleverdon, Librarian of the Cranfield Institute of Technology. For this work he received the Professional Award of the Special Libraries Association in 1962 and the Award of Merit of the American Society for Information Science in 1970. The objective of the experiment, called Cranfield I, was to test the ability of four indexing systems-UDC, Facet, Uniterm, and Alphabetic-Subject Headings-to retrieve material responsive to questions addressed to a collection of documents. The experiment was ambitious in scale, consisting of eighteen thousand documents and twelve hundred questions. Prior to Cranfield I, the question of what constitutes good indexing was approached subjectively and reference was made to assumptions in the form of principles that should be observed or user needs that should be met. Cranfield I was the first large-scale effort to use objective criteria for determining the parameters of good indexing. Its creative impetus was the definition of user satisfaction in terms of precision and recall. Out of the experiment emerged the definition of recall as the percentage of relevant documents retrieved and precision as the percentage of retrieved documents that were relevant. Operationalizing the concept of user satisfaction, that is, making it measurable, meant that it could be studied empirically and manipulated as a variable in mathematical equations. Much has been made of the fact that the experimental methodology of Cranfield I was seriously flawed. This is unfortunate as it tends to diminish Cleverdon's contribu tion, which was not methodological-such contributions can be left to benchmark researchers-but rather creative: the introduction of a new paradigm, one that proved to be eminently productive. The criticism leveled at the methodological shortcomings of Cranfield I underscored the need for more precise definitions of the variables involved in information retrieval. Particularly important was the need for a definition of the dependent variable index language. Like the definitions of precision and recall, that of index language provided a new way of looking at the indexing process. It was a re-visioning that stimulated research activity and led not only to a better understanding of indexing but also the design of better retrieval systems." Cranfield I was followed by Cranfield II. While Cranfield I was a wholesale comparison of four indexing "systems," Cranfield II aimed to single out various individual factors in index languages, called "indexing devices," and to measure how variations in these affected retrieval performance. The following selection represents the thinking at Cranfield midway between these two notable retrieval experiments.

0.016749864 = product of:
  0.08374932 = sum of:
    0.08374932 = weight(_text_:22 in 6158) [ClassicSimilarity], result of:
      0.08374932 = score(doc=6158,freq=2.0), product of:
        0.18038483 = queryWeight, product of:
          3.5018296 = idf(docFreq=3622, maxDocs=44218)
          0.051511593 = queryNorm
        0.46428138 = fieldWeight in 6158, product of:
          1.4142135 = tf(freq=2.0), with freq of:
            2.0 = termFreq=2.0
          3.5018296 = idf(docFreq=3622, maxDocs=44218)
          0.09375 = fieldNorm(doc=6158)
  0.2 = coord(1/5)

Footnote

Rez. in: College and research libraries 22(1961) no.3, S.228 (G. Jahoda)