The Flesch/Flesch–Kincaid readability tests are designed to indicate comprehension difficulty when reading a passage of contemporary academic English. There are two tests, the Flesch Reading Ease, and the Flesch–Kincaid Grade Level. Although they use the same core measures (word length and sentence length), they have different weighting factors. The results of the two tests correlate approximately inversely: a text with a comparatively high score on the Reading Ease test should have a lower score on the Grade Level test. Rudolf Flesch devised both systems while J. Peter Kincaid developed the latter for the United States Navy. Such readability tests suggest that many Wikipedia articles may be "too sophisticated" for their readers.[1]

## History

"The Flesch–Kincaid" (F–K) Reading grade level was developed under contract to the United States Navy in 1975 by J. Peter Kincaid and his team.[2] Other related United States Navy research directed by Kincaid delved into high tech education (for example, the electronic authoring and delivery of technical information);[3] usefulness of the Flesch–Kincaid readability formula;[4] computer aids for editing tests;[5] illustrated formats to teach procedures;[6] and the Computer Readability Editing System (CRES).[7]

The F-K formula was first used by the United States Army for assessing the difficulty of technical manuals in 1978 and soon after became the Department of Defense military standard. The Commonwealth of Pennsylvania was the first state in the United States to require that automobile insurance policies be written at no higher than a ninth grade level (14 to 15 years of age) of reading difficulty, as measured by the F-K formula. This is now a common requirement in many other states and for other legal documents such as insurance policies.[4]

In the Flesch Reading Ease test, higher scores indicate material that is easier to read; lower numbers mark passages that are more difficult to read. The formula for the Flesch Reading Ease Score (FRES) test is

$206.835 - 1.015 \left ( \frac{\mbox{total words}}{\mbox{total sentences}} \right ) - 84.6 \left ( \frac{\mbox{total syllables}}{\mbox{total words}} \right )$[8]

Scores can be interpreted as shown in the table below.

Score Notes
90.0–100.0 easily understood by an average 11-year-old student
60.0–70.0 easily understood by 13- to 15-year-old students
0.0–30.0 best understood by university graduates

Many government agencies require documents or forms to meet specific readability levels.

The U.S. Department of Defense uses the Reading Ease test as the standard test of readability for its documents and forms.[10] Florida requires that life insurance policies have a Flesch Reading Ease score of 45 or greater.[11]

Use of this scale is so ubiquitous that it is bundled with popular word processing programs and services such as KWord, IBM Lotus Symphony, Microsoft Office Word, WordPerfect, and WordPro.

Polysyllabic words affect this score significantly more than they do the grade level score.

These readability tests are used extensively in the field of education. The "Flesch–Kincaid Grade Level Formula" translates the 0–100 score to a U.S. grade level, making it easier for teachers, parents, librarians, and others to judge the readability level of various books and texts. It can also mean the number of years of education generally required to understand this text, relevant when the formula results in a number greater than 10. The grade level is calculated with the following formula:

$0.39 \left ( \frac{\mbox{total words}}{\mbox{total sentences}} \right ) + 11.8 \left ( \frac{\mbox{total syllables}}{\mbox{total words}} \right ) - 15.59$

The result is a number that corresponds with a grade level. For example, a score of 8.2 would indicate that the text is expected to be understandable by an average student in year 8 in the United Kingdom (usually around ages 12–14 in the United States of America). The sentence, "The Australian platypus is seemingly a hybrid of a mammal and reptilian creature" is a 13.1 as it has 26 syllables and 13 words.

The lowest grade level score in theory is −3.40, but there are few real passages in which every sentence consists of a single one-syllable word. Green Eggs and Ham by Dr. Seuss comes close, averaging 5.7 words per sentence and 1.02 syllables per word, with a grade level of −1.3. (Most of the 50 used words are monosyllabic; "anywhere", which occurs 8 times, is the only exception.)

## References

1. ^ Anderson, Kent (September 24, 2012). "Wikipedia’s Writing — Tests Show It’s Too Sophisticated for Its Audience". Scholarly Kitchen. Retrieved December 7, 2012.
2. ^ Kincaid, J.P., Fishburne, R.P., Rogers, R.L., & Chissom, B.S. (1975). Derivation of New Readability Formulas (Automated Readability Index, Fog Count, and Flesch Reading Ease formula) for Navy Enlisted Personnel. Research Branch Report 8-75. Chief of Naval Technical Training: Naval Air Station Memphis.
3. ^ Kincaid JP, Braby R, Mears J (1988). "Electronic authoring and delivery of technical information". Journal of Instructional Development 11: 8–13.
4. ^ a b McClure G (1987). "Readability formulas: Useful or useless. (an interview with J. Peter Kincaid.)". IEEE Transactions on Professional Communications 30: 12–15.
5. ^ Kincaid JP, Braby R, Wulfeck WH II (1983). "Computer aids for editing tests". Educational Technology 23: 29–33.
6. ^ Braby R, Kincaid JP, Scott P, McDaniel W (1982). "Illustrated formats to teach procedures". IEEE Transactions on Professional Communications 25: 61–66.
7. ^ Kincaid JP, Aagard JA, O'Hara JW, Cottrell LK (1981). "Computer Readability Editing System". IEEE Transactions on Professional Communications 24 (1): 38–42. (also reported in Aviation Week and Space Technology, 11 January 1982, pp. 106-107.)
8. ^ http://www.editcentral.com/gwt1/EditCentral.html
9. ^ http://www.gutenberg.org/files/2701/2701-h/2701-h.htm#2HCH0064
10. ^ Luo Si, et al. (5–10 November 2001). "A Statistical Model for Scientific Readability". Atlanta, GA, USA: CIKM '01.
11. ^ "Readable Language in Insurance Policies"