So you have uploaded your document to VisibleThread and clicked on the 'Plain Language' tab to check the readability statistics.

After reviewing the results, you spend time removing all passive voice and shortening all those long sentences. Finally you upload your new version of the document to VisibleThread. Clicking on the 'Plain Language' tab you expect to see the readability score shoot up, but it doesn't, it stays exactly the same. What gives?

Understanding VisibleThread Readability Score

To start, lets explain what exactly is meant by the 'Readability' score in VisibleThread.

The readability score is actually the Flesch Reading Ease of the document.  The Flesch Reading Ease is a popular scale that measures   "Textual difficulty" (http://simple.wikipedia.org/wiki/Textual_difficulty), indicating how easy a text is to read. The scale has been adopted by the U.S. Department of Defense as the standard test for readability of documents.

The Readability score is calculated using a formula based on the length of sentences in the document, and the number of multi-syllable or complex words, the latter having the most significant weighting.

I don't seem to be able to improve the readability score for my document, does this mean its too complex?

No, not necessarily. Its important to remember that Readability is just one of the metrics VisibleThread provides to help you make your documents easier to understand. Usually it is more useful to focus on the Long Sentences  and Passive Voice scores for your document. Reducing the amount of Long Sentences and Passive Voice in your document will result in a document that is much easier to digest and  understand. We strongly recommend users use Long Sentence and Passive Voice thresholds when reviewing documents. For example, a document must have lower than 4% passive voice and 5% Long Sentences before it passes the Plain Language test.

Reducing Passive Voice and Long Sentences may well result in a higher readability score, but then again it may not. The principal reason for this is that multi-syllabic or 'complex' words play a much higher factor in the calculation of the readability score than anything else. Two things to consider:

• The plainlanguage.gov website has published a list of common complex words and some simpler alternatives. Placing these into a VisibleThread dictionary will allow you to scan your document for these words and help you replace them with simpler alternatives. This may improve the readability score. See the attachment for a CSV file containing these words that you can import into your VisibleThread environment.
• In some cases it may not be possible to achieve a good readability score for your document. This tends to be the case for shorter documents (less than 3 pages for example) that contain a large density of complex terms. Often technical documents will score low on the readbility scale purely due to the complex terminology used. For example the passage of text below reads perfectly fine, however scores 0 for readability:

 

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In summary, the Readability score is  a useful metric to gauge how readable to text in your document is improving between revisions. However there may be a limit to how high that score can go depending on the size/type of document you are creating. It is often more useful to focus on reducing passive voice and long sentences in your text which will itself produce a more readable document.