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Use Caution When Using Readability Formulas like Flesch Reading Ease

Understand the context and the audience before wildly applying readability formulas.  Are you writing with FINESSE?
Understand the context and the audience before wildly applying readability formulas.

Readability formulas determine how easily a specific audience can understand a text. There are more than a dozen readability formulas, such as Flesch Reading Ease, the Flesch-Kincaid Grade Level, the Simple Measure of Gobbledygook (SMOG), the Gunning-FOG Index, and the Coleman-Liau Index. Many Google, Microsoft, and Adobe products have a built-in readability formula. Editing tools such as Grammarly do, too. The one big thing to remember is that too much attention to readability scores does not mean your writing is easier to comprehend or understand.

How it Works

Most readability formulas use some combination of sentence length, the average number of words per sentence, the average number of characters per word, or the number of words with three or more syllables. You can use the formulas to score text by hand. The results from these formulas are often given as a grade level, such as “4th grade” or “12th grade.”

Why Be Cautious About Formulas?

Most technical professionals are unaware of the narrow, mechanical focus of readability formulas. We focus too much on pushing the grade level scores down, which is not the best solution in all contexts.

Grade Level Score is Based on Length of Words and Sentences

Readability formulas generally assume that longer words are harder words and longer sentences are harder sentences. They can’t tell you whether the words you are using are familiar to your readers. Readability formulas cannot tell you whether the sentences you have written in a paragraph or document are cohesive.

The Formulas Do Not Measure Comprehension or Engagement

Readability formulas completely ignore most factors that contribute to ease of reading and comprehension. A grade-level score tells you nothing about whether your text will attract and hold people’s attention. Nor will it tell you whether the content is effectively organized or whether people can understand and use it. This means that a grade level score, by itself, is not a good way to judge the overall suitability of your report.

There are Measurement Issues

Grade-level scores for the same text can differ by several grade levels, depending on which formula is used and the logic used to assign the grade levels. Remember, too, that text not in full sentences, such as headings and bulleted points, will also hurt your score.

Using the Formulas as a Diagnostic Tool

Readability scores can be a good tool for alerting you that your text is too difficult and that you need to make revisions. Readability experts often advise that the scores be interpreted in a more general way.

  • Material written at the fourth- to sixth-grade level is considered easy to read.

  • Seventh- to ninth-grade materials are considered to be of average difficulty.

  • Anything written at a 10th-grade level or above is considered difficult.

Solutions for Improving Reading Ease

1. Establish the context.

Start by estimating your audience’s reading skills. Research has found that a person’s reading level is usually 3 to 5 years below the highest grade that person has completed.

2. Estimate the reader’s experience level within the technical area, such as reliability.

One rule of thumb is to knock off 1 to 2 levels of expertise from what you perceive a person has.

3. Take a close look at your words and sentences.

The long words (three or more syllables) and long sentences give your text a high grade-level score.

  • Identify the long words and decide whether they will be familiar to your readers.

  • Identify any shorter words you think might be difficult for your readers.

  • Identify the lengthy sentences and consider whether they will likely be hard for your readers to understand.

  • Identify any shorter sentences that might be hard for people to understand.

Writing with FINESSE

Readability formulas are one tool in the toolbox for helping you Communicate with FINESSE. Remember, the three barriers to communication are language, visual and hearing impairments, and generational differences. Shorter words and sentences help with all three. However, readability formulas do not guarantee that your writing will hold the reader's attention, make it easier to understand, or make it more useable. Use readability formulas cautiously as one form of diagnostic tool.


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