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	Multidimensional Register Analysis	Keyness Analysis
分野	言語学	言語学
系統	Process / pipeline	Process / pipeline
提唱年	1988	1997
提唱者	Douglas Biber	Mike Scott
種類	Factor-analytic analysis of co-occurring linguistic features across registers	Corpus comparison of relative word frequencies
原典	Biber, D. (1988). Variation across Speech and Writing. Cambridge University Press. ISBN: 9780521425568	Scott, M. (1997). PC analysis of key words — and key key words. System, 25(2), 233–245.
別名	Multidimensional Analysis (MD/MDA), Biber's Multidimensional Analysis, Dimensions of Register Variation	Keyword Analysis, Corpus Keyness, Keyness Statistics
関連	4	3
概要	Multidimensional (MD) analysis is a corpus-linguistic method, developed by Douglas Biber in the 1980s, for describing how language varies across registers — speech versus writing, conversation versus academic prose, and so on. Its central idea is that many individual linguistic features (pronouns, passives, nominalizations, modals, and dozens more) systematically co-occur, and that these co-occurrence patterns define underlying dimensions of variation. Biber tags and counts a large set of features in every text of a balanced corpus, then uses factor analysis to extract the dimensions, interprets each functionally (Biber's Dimension 1 contrasts 'involved' interactive production with 'informational' production), and scores every text and register along them. The result is a quantitative, multifaceted map of register variation that replaces single rankings (such as a simple formality scale) with several independent dimensions.	Keyness analysis identifies the words that are characteristically frequent (or infrequent) in a target corpus relative to a reference corpus, using statistical tests to measure how unexpected each word's frequency is. Introduced by Mike Scott in 1997, it answers the question 'what is this text or collection distinctively about?' and is a central technique in corpus linguistics and corpus-assisted discourse analysis for surfacing the salient vocabulary of a genre, period, author, or social group.