Details of Lexical Richness Measures

The two fundamental building blocks of all the measures are:

  • the total number of words in the text (w) , and

  • the number of unique terms (t).

TTR: Type-Token Ratio (Chotlos 1944, Templin 1957)

TTR

RTTR: Root Type-Token Ratio (Guiraud 1954, 1960)

TTR

CTTR: Corrected Type-Token Ratio (Carrol 1964)

TTR

Herdan: Herdan’s C (Herdan 1960, 1964)

Herdan's C

Summer: Summer (Summer 1966)

Summer

Dugast: Dugast (Dugast 1978)

Dugast

Maas: Maas (Maas 1972)

Maas

Yule’s K (Yule 1944, Tweedie and Baayen 1998)

Yule's K

Yule’s I (Yule 1944, Tweedie and Baayen 1998)

Yule's I

Herdan’s Vm (Herdan 1955, Tweedie and Baayen 1998)

Herdan's Vm

Simpson’s D (Simpson 1949, Tweedie and Baayen 1998)

Simpson's D