Table 2.

Indices of lexical richness examined in the study.

Construct	Label	Definition
Lexical density	Nlex/N	The percent of lexical words
Lexical variation	MATTR	Moving average TTR
	Maas	A log correcting measure
	HD-D	The hypergeometric distribution D
	MTLD	The measure of textual lexical variation
Lexical sophistication
Frequency	AWL	Academic word list all
	Bigram	BNC Written bigram frequency
	Written-CW	BNC written frequency CW logarithm
	Trigram	BNC written trigram frequency
Range	KFR_CW	Kucera-Francis register range CW
	WR-AW	BNC written range AW
Word property	Familiarity	MRC familiarity CW
	Meaningfulness	MRC meaningfulness AW
Word specificity	Polysemy	Polysemy verbs
	Hypernymy	Hypernymy nouns and verbs