Gunning fog index
readability test
In linguistics, the Gunning fog index is a readability test for English writing. The index estimates the years of formal education a person needs to understand the text on the first reading. For instance, a fog index of 12 requires the reading level of a United States high school senior (around 18 years old). The test was developed in 1952 by Robert Gunning, an American businessman who had been involved in newspaper and textbook publishing.
The fog index is commonly used to confirm that text can be read easily by the intended audience. Texts for a wide audience generally need a fog index less than 12. Texts requiring near-universal understanding generally need an index less than 8.
Calculation
The Gunning fog index is calculated with the following algorithm:
Select a passage (such as one or more full paragraphs) of around 100 words. Do not omit any sentences;
Determine the average sentence length. (Divide the number of words by the number of sentences.);
Count the "complex" words consisting of three or more syllables.
The public source identifies “Gunning fog index” as readability test. This brief keeps that definition visible, then builds a research path around Gunning, index and readability.
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This entry incorporates text from “Gunning fog index” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.