The readability of texts can be assessed by applying an automated algorithm. Such a measure can give an indication of how hard it is for someone to read and comprehend a text.
In this demo, we apply the Flesch Reading Ease Test to articles from Wikipedia. This test incorporates two measures deemed relevant to readability, namely sentence length (#words) and word length (#syllables). Reading ease is calculated by the formula:
RE = 206,835 - (1,015 SL) - (84,6 WL)
The outcome of this formula can be interpreted by the following table:
|0 - 30||Very difficult|
|30 - 50||Difficult|
|50 - 60||Fairly difficult|
|60 - 70||Standard|
|70 - 80||Fairly Easy|
|80 - 90||Easy|
|90 - 100||Very Easy|
When writing for a general public, one should aim for a score between 60 and 70. Academic publications mostly score below 30.
Note that the formula only works for English texts. Different languages may have different averages for sentence and word length, which means that the formula should be adapted for this.
The Flesch Reading Ease Test is used by the U.S. Department of Defense to indicate the readability of their official documents. Florida state law requires insurance policies to have a reading ease of at least 45, to ensure that people can understand them.
The average readability of the English Wikipedia was around 48 (August, 2010). This may be a bit too difficult for a general public. The Simple English Wikipedia scores higher with a score of around 60, but for a public with a limited language proficiency, this still may be too difficult.
Read more about the readability of Wikipedia in the related paper: