ABSTRACT
Lexical richness is an umbrella term that refers to the density, sophistication, and variety of vocabulary in a language sample such as an essay or spoken response. In language learning contexts, higher proficiency language users are presumed to produce language that is more lexically dense and sophisticated, and that includes a wider variety of lexical items.
The focus of this chapter is describing the ways in which lexical richness has been and can be measured. Each of the three categories (density, sophistication, and variety) are discussed from both theoretical and practical perspectives. Findings of key studies in each area are reviewed.
Also included is a discussion of important measurement issues (e.g., raw tokens, lemmas, and families, statistical transformations) in each area. Available tools for the measurement of lexical richness are also introduced and discussed (e.g., RANGE, VocabProfile, and TAALES).
