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A bibliogram is a verbal construct made when noun phrases from extended stretches of text are ranked high to low by their frequency of co-occurrence with one or more user-supplied seed terms. Each bibliogram has three components: * A seed term that sets a context. * Words that co-occur with the seed across some set of records. * Counts (frequencies) by which co-occurring words can be ordered high to low. The term was introduced in 2005 by Howard D. White to name the linguistic object studied, but not previously named, in informetrics, scientometrics and bibliometrics. The noun phrases in the ranking may be authors, journals, subject headings, or other indexing terms. The "stretches of text” may be a book, a set of related articles, a subject bibliography, a set of Web pages, and so on. Bibliograms are always generated from writings, usually from scholarly or scientific literatures. As a family of term-frequency distributions, the bibliogram has frequently been written about under descriptions such as: * positive skew distribution * empirical hyperbolic * scale-free (see also Scale-free network) * power law * size frequency distribution * reverse-J It is sometimes called a "core and scatter" distribution. The "core" consists of relatively few top-ranked terms that account for a disproportionately large share of co-occurrences overall. The "scatter” consists of relatively many lower-ranked terms that account for the remaining share of co-occurrences. Usually the top-ranked terms are not tied in frequency, but identical frequencies and tied ranks become more common as the frequencies get smaller. At the bottom of the distribution, a long tail of terms are tied in rank because each co-occurs with the seed term only once. In most cases bibliograms can be described by power laws such as Zipf's law and Bradford's law. In this regard, they have long been studied by mathematicians and statisticians in information science. However, these treatments typically ignore the qualitative meanings of the ranked terms themselves, which are often of interest in their own right. For example, the following bibliogram was made with an author's name as seed and shows the descriptors that co-occur with her name in the ERIC database. The descriptors are ranked by how many of her articles they were used to index: 6 Creativity 4 Creativity Tests 3 Divergent Thinking 2 Elementary School Mathematics 2 Instruction 2 Mathematics Education 2 Problem Solving 2 Research 2 Time 1 Acceleration 1 Anxiety 1 Beginning Teachers 1 Behavioral Objectives 1 Child Development 1 Classroom Techniques 1 Cognitive Development etc. This author is a researcher in education, and it will be seen that the terms profile her intellectual interests over the years. In general, bibliograms can be used to: 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bibliogram」の詳細全文を読む スポンサード リンク
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