Compare methods

	Measure of Textual Lexical Diversity (MTLD)	Lexical Diversity
Field	Linguistics	Text mining
Family	Process / pipeline	Process / pipeline
Year of origin	2005	—
Originator	Philip M. McCarthy	—
Type	Length-robust index of lexical diversity	Text quantification / lexical richness measurement
Seminal source	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.	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.
Aliases	MTLD, Measure of Textual Lexical Diversity, Sequential TTR Factor Measure	lexical richness, vocabulary richness, Sözcüksel Çeşitlilik Analizi
Related	4	3
Summary	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.	Lexical diversity analysis quantifies how varied the vocabulary of a text is — how rich an author's word choice is — using measures such as the type-token ratio (TTR), MTLD, vocd-D, and Yule's K. The MTLD and vocd-D measures were validated by McCarthy and Jarvis (2010), building on earlier work by Tweedie and Baayen (1998) on the stability of lexical-richness measures.