The Dale–Chall readability formula is a
readability test
Readability is the ease with which a reader can understand a written text. In natural language, the readability of text depends on its content (the complexity of its vocabulary and syntax) and its presentation (such as typographic aspects that a ...
that provides a numeric gauge of the comprehension difficulty that readers come upon when reading a text. It uses a list of 3000 words that groups of fourth-grade American students could reliably understand, considering any word not on that list to be difficult.
History
The formula was inspired by
Rudolf Flesch
Rudolf Franz Flesch (8 May 1911 – 5 October 1986) was an Austrian-born naturalized American writer (noted for his book ''Why Johnny Can't Read''), and also a readability expert and writing consultant who was a vigorous proponent of plain Engli ...
's
Flesch–Kincaid readability test which used word-length to determine how difficult a word was for readers to understand.
Edgar Dale
Edgar Dale (April 27, 1900 in Benson, Minnesota, – March 8, 1985 in Columbus, Ohio) was an American educator who developed the Cone of Experience, also known as the Learning Pyramid. He made several contributions to audio and visual instruct ...
and
Jeanne Chall
Jeanne Sternlicht Chall (January 1, 1921 – November 27, 1999), a Harvard Graduate School of Education psychologist, writer, and literacy researcher for over 50 years, believed in the importance of direct, systematic instruction in reading in spit ...
instead used a list of 769 words that 80% of fourth-grade students were familiar with, such as "no", "yes", and other such very basic words to determine which words were difficult. The Dale-Chall Readability Formula was originally published in their 1948 article ''A Formula for Predicting Readability''
and updated in 1995 in ''Readability Revisited: The New Dale-Chall Readability Formula'', which expanded the word list t
3,000 familiar wordstext file version
.
Formula
The formula for calculating the raw score of the Dale–Chall readability score (1948) is given below:
:
If the percentage of difficult words is above 5%, then add 3.6365 to the raw score to get the adjusted score, otherwise the adjusted score is equal to the raw score. Difficult words are all words that are not on the word list, but it has to be considered that the word list contains the basic forms of e.g. verbs and nouns. Regular plurals of nouns, regular past tense forms, progressive forms of verbs etc. have to be added.
See also
*Readability
Readability is the ease with which a reader can understand a written text. In natural language, the readability of text depends on its content (the complexity of its vocabulary and syntax) and its presentation (such as typographic aspects that a ...
References
{{DEFAULTSORT:Dale-Chall readability formula
Readability tests