手法を比較

	Measure of Textual Lexical Diversity (MTLD)	N-gram Analysis
分野	言語学	言語学
系統	Process / pipeline	Process / pipeline
提唱年	2005	1999
提唱者	Philip M. McCarthy	Corpus linguists (Douglas Biber; lexical bundles tradition)
種類	Length-robust index of lexical diversity	Frequency analysis of contiguous word sequences
原典	McCarthy, P. M., & Jarvis, S. (2010). MTLD, vocd-D, and HD-D: A validation study of sophisticated approaches to lexical diversity assessment. Behavior Research Methods, 42(2), 381–392.	Biber, D., Johansson, S., Leech, G., Conrad, S., & Finegan, E. (1999). Longman Grammar of Spoken and Written English. Longman. ISBN: 9780582237254
別名	MTLD, Measure of Textual Lexical Diversity, Sequential TTR Factor Measure	Lexical Bundle Analysis, Cluster Analysis (corpus linguistics), Contiguous Sequence Analysis
関連	4	4
概要	The Measure of Textual Lexical Diversity (MTLD) is a length-robust index of vocabulary richness introduced by Philip McCarthy in 2005 and validated by McCarthy and Jarvis in 2010. Rather than computing a single ratio over the whole text, MTLD reads the text word by word, tracking a running type-token ratio, and counts how many sequential word runs are needed before the ratio repeatedly falls to a criterion value of 0.720. The mean length of those runs, computed forward and backward and averaged, is the MTLD score — and in validation studies it was the one common index that did not vary systematically with text length.	N-gram analysis is a corpus-linguistic technique that extracts and ranks every contiguous sequence of n words (or characters) in a corpus, exposing the recurrent multi-word units — two-word bigrams, three-word trigrams, and longer 'lexical bundles' — that make up a register or text type. By counting how often each sequence recurs, it reveals the prefabricated, formulaic backbone of language that single-word frequency lists cannot capture.