Compare methods

	vocd-D (D Measure)	Lexical Diversity
Field	Linguistics	Text mining
Family	Process / pipeline	Process / pipeline
Year of origin	2004	—
Originator	David Malvern & Brian Richards	—
Type	Length-robust index of lexical diversity	Text quantification / lexical richness measurement
Seminal source	Malvern, D., Richards, B., Chipere, N., & Durán, P. (2004). Lexical Diversity and Language Development: Quantification and Assessment. Palgrave Macmillan. ISBN: 9781403902313	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	vocd-D, D Measure, vocd, HD-D	lexical richness, vocabulary richness, Sözcüksel Çeşitlilik Analizi
Related	4	3
Summary	vocd-D, also called the D measure, is a length-robust index of lexical diversity developed by David Malvern and Brian Richards. Instead of reporting a single type-token ratio, it characterizes how a text's TTR falls as sample size grows and fits that empirical curve to a one-parameter probabilistic model; the fitted parameter D is the diversity score, with higher D meaning richer vocabulary. HD-D, introduced by McCarthy and Jarvis, is the mathematically exact, sampling-free counterpart that computes the same underlying quantity directly from the hypergeometric distribution.	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.