What you might not know about readability testing

There’s a lot to know about tests that measure the difficulty of reading passages.

First, these tests have something in common: they count syllables, words, and sentences in reading passages to come up with an average word and sentence length. These core factors then are used to develop a score that indicates how difficult (or easy) it may be for a reader to comprehend a piece of reading. I say, “may,” because this is not an exact science. But “the application of a useful readability test protocol will give a rough indication of a work’s readability.”

Second, these tests are widely used ─ by publishers, schools, businesses, word processing applications, and parents. Publishers use the readability scores to aim publications at their target readers; schools use them to identify appropriate texts for students; and businesses use them to calibrate the reading level for forms, guidelines, and training manuals that must be comprehended by their workers. Most word processing applications have readability tests built-in as an option for document editing. And parents use them to select appropriate reading materials for their children.

Third, there are several tests out there though two seem to dominate the readability marketplace.

Flesch–Kincaid. Two types of readability tests have been created to indicate how difficult a passage in English is to understand: Flesch Reading Ease and Flesch–Kincaid Grade Level. Both use word length and sentence length to develop their scores but they use different weighting factors. The Army first used the Flesch-Kincaid Reading Ease nearly 40 years ago to assess the difficulty of its technical manuals. The U.S. Department of Defense uses this now as the standard test of readability for its documents and forms. Some states have adopted the test in specific industries such as automobile insurance policies to ensure that the reading “ceiling” be no higher than ninth-grade level. The test is bundled with many word processing programs and services such as IBM Lotus Symphony, Microsoft Office Word, WordPerfect, and WordPro.

In Flesch-Kincaid, a higher score indicates material that is easier to read; lower score, more difficult to read. Here are some examples of the approximate readability score for well-known publications or audiences (highest score/easiest is 120):

 * Reader’s Digest magazine = about 65
 * Time magazine = about 52
 * Average student writing assignment grade 6 (age 12) = 60–70; reading grade level of 6-7)
 * Harvard Law Review = low 30s
 * Life insurance policies in Florida = 45 or greater
 * Moby Dick (book) = average 57.9
 * Harry Potter books = average 72.83
 * 2000 articles about people in Wikipedia with most readable about sports people and entertainers, least readable about scientists and philosophers with least readable scientists being economists (41.70), psychologists (42.25), chemists (42.81), mathematicians (43.35)

The Flesch–Kincaid Grade Level Formula is used extensively in the field of education. Scores are presented as a grade level (the number of years of education generally required to understand the text) rather than a readability score. This makes it easier for educators, parents, and others to determine the readability level of reading materials for students.

Lexile. A Lexile is a number score for an individual’s reading ability or a text’s readability. It is represented as a number followed by L for Lexile. There are two types of measures: a reader and a text measure. The scale runs from below zero L to above 2000L. There is no specific bottom or top score though scores of zero L (0L) or below are reported as Beginning Reader.

The Lexile framework emerged over more than a decade of work that began in 1989 to develop a better measurement system for reading and writing. The framework uses quantitative methods based on individual words and sentence lengths rather than qualitative analysis of content to produce readability scores. In the U.S., Lexile scores are reported from school-based reading programs and student assessments annually. About half of U.S. students in grades 3-12 receive a Lexile measure annually. Lexile measures have been adopted by nearly half of the states, school districts in all 50 states, and used outside the U.S.

Lexile scores are used to match readers with books and other reading resources. Both readers and books/other reading resources are assigned a score on the Lexile scale. Lower scores indicate easier readability for reading materials and lower reading ability for readers. [This is opposite from Flesch–Kincaid scores in which higher scores equal easier readability.]

Lexile measures for individuals are typically obtained from a reading comprehension assessment or program. These range from basic early literacy skills to the adult level. Text measures are obtained by analyzing the word frequency and sentence length within a book or article using a software program, the Lexile Analyzer. To date, over 60,000 websites, 115,000 fiction and nonfiction books, and 80 million articles have Lexile measures. Over 150 publishers (e.g., Capstone Publishers, Discovery Ed, Houghton Mifflin Harcourt, McGraw-Hill, Pearson PLC, Riverside Publishing, Scholastic Corporation, Simon & Schuster, Workman Publishing Company, and World Book) offer certified Lexile text measures for their materials.

Although there is widespread use of Lexile measures in schools and in publishing, there is no direct correspondence between a Lexile measure and a specific grade level, and there are cautionary views of their use. For example, an evaluation of the Lexile measures in 2001 by the National Center for Educational Statistics “affirmed the value of both sentence length and word frequency” as measures of readability, but the measures do not include factors such as reader knowledge, motivation and interest which also have a major impact on readability.

The Lexile measures, as well as other products and services for reading, math, and writing are created by MetaMetrics®. The North Carolina company focuses on improving education for learners of all ages, developing scientific measures of academic achievement and complementary technologies that link assessment results with real-world instruction. In addition to licensing metrics tools to state departments of education, testing and instructional companies, and publishers, MetaMetrics offers training, resource measurement and customized consulting services. A short video that explains the Lexile is available here: https://lexile.com/pd/video/