It's easy to infer from the name, readability formulas, that the formulas measure reading ease or comprehension which, as we've just discussed, they do not. Nonetheless, many writers and teachers use readability formulas to meet a target reading level, such as "write it at the sixth grade level."
When writers and teachers use readability scores as a criterion, they do so with good intentions: they want to make sure their material is not too difficult for their readers. While it's crucial to match reading skills with the difficulty of the material, an appropriate reading grade level does not by itself ensure the match is perfect. Using grade level standards based on readability formulas can lead writers to produce text that is less readable, even though it scores at a lower grade level.
If you must meet a standard of a "sixth grade level," and your material scores at an 8th grade level, what can you do? It can be tempting to manipulate your text by dividing sentences and substituting shorter words. Although this type of editing will improve your grade level score, it may make your text choppy and harder to read. Substituting shorter words and shortening sentences may not benefit your readers.
1) Sometimes a longer word is a familiar word, so there's no reason to change it.
2) Sometimes readers need to know the longer word. Teaching its meaning may require you to repeat the longer word several times Repeating the long word will inflate the grade level score for the material, but repeating it will help your reader understand and use the new word.
3) Breaking up a longer sentence may reduce its cohesion, putting a new burden on your readers to supply the connections you just removed.
Relying heavily on grade level standards can also cause other problems, such as:
1) Using a grade level score as an overall indicator may give you a false sense of confidence and cause you to miss problemswith your material. Even if you achieve a reading grade level that matches your readers' grade level, your readers may still find your material hard and confusing.
2) Using grade level scores as a standard may encourage people to treat grade level scores at face value, rather than as rough approximations. As already noted, readability formulas may provide inaccurate measurements of a text. Because scores can vary greatly and be unreliable, it makes sense to interpret readability scores with caution.
Interpreting readability scores
Readability scores are not measures of comprehension, even though sometimes writers interpret them that way. Readability scores reflect only one of many factors that affect ease of reading and usability of the materials. A readability formula screens for difficulty of words and sentences, but it does not account for the life experience, literacy skills, and educational backgrounds that readers bring to the task of reading.
Many readability formula focuses narrowly on what is easy to count at the level of individual words and sentences and ignores everything else. Counts of syllables and sentences cannot tell you if the layout is effective, or if your writing is clear, cohesive, and well organized. These counts cannot tell you if readers find the information appealing, easy to understand, and easy to use.
Since readability formulas only measure the length of words and sentences, it is not appropriate to use the results to firmly judge the suitability of materials. Direct feedback from your test readers during the writing process is the ultimate test.