lexical density

In STATISTICAL LINGUISTICS and LEXICAL studies, a measure of the difficulty of a TEXT, using the ratio of the number of different WORDS in a text (the ‘word types’) to the total number of words in the text (the ‘word tokens’); also called the type/token ratio (TTR). It is calculated by dividing the number of different words by the total number of words and multiplying by 100. The result is given as a percentage. The assumption is that increasing the number of different words (i.e. a higher TTR) increases textual difficulty.