Fun with Flesch-Kincaid
Old users of Microsoft Office (and I don’t mean that the users are of old age) might remember the statistics window that pops up after they perform a grammar check. For some reason recent versions of Microsoft Office disable the readability statistics by default.
One of the things presented in the statistics are the Flesch-Kincaid Readibility Test, namely the Flesch Reading Ease and Flesch-Kincaid Grade Level. Flesch-Kincaid is a measure of comprehension difficulty when reading a contemporary academic English passage. The figures are derived from several factors:
- average number of words in a sentence
- average number of syllables in a word
The Flesch Reading Ease is derived using the formula:
The scoring system means that higher-scoring passages are easier to understand than those of lower scores. As a rough measure, passages scoring 90-100 can be understood by an average 11-year old student, 60-70 by 13- to 15-year old students, and 0-30 by college graduates.
The Flesch-Kincaid Grade Level, on the other hand, is a similar measure using the US grade level as a unit. It goes by the formula:
For example, a score of 10 means that students in the 10th grade should be able to understand the passage.
Well, I’ve described one of the statistics measures that can be taken from an English passage. The more interesting thing that I found was a list of such Flesch-Kincaid statistics as calculated from the State of the Union speeches delivered by US presidents from the time of George Washington.
The State of the Union Address is an annual message that the president delivers to the Congress, in which the president “give to Congress information of the State of the Union and recommend to their Consideration such measures as he shall judge necessary and expedient”.
There are some interesting facts from the list. For example, the easiest speech to read is by Goerge H.W. Bush in January 28, 1992, with a Reading Ease of 54.98 and Grade Level of 9.45. This means that most 9th grade students should be able to understand it.
The other end of the spectrum is James Madison’s speech on December 5, 1815. It has a Reading Ease value of -1.91, and Grade Level of 26.16. This is probably one of the lowest Reading Ease values I’ve ever seen (it’s negative!), requiring at least 26 years of education just to understand the speech. The speech also has the highest average number of words per sentence at 50.87 words per sentence. Imagine giving a speech with that average number of words!
A graph provided in the website also shows that as time goes by, the Reading Ease steadily decreases. This can mean a couple of things. One is that
the intelligence of the presidents has decreased over time the presidents want their speeches to be more easily understood. Another possibility is that it is just a matter of style of English as it is used in different periods. It then means that it might just not be a good idea to use the Flesch-Kincaid measures to compare English passages from different periods.
The moral of the story here is… well, there is no moral of the story, really. Maybe something that we can learn from the calculations is that to make our passages easier to understand, we should try to minimize the average number of words per sentence and the average number of syllables per word.
However we have to remember that the Flesch-Kincaid Readibility Test is merely a statistical measure. Obviously having a very high Reading Ease and very low Grade Level is not practical. To obtain such values, words have to have a low number of syllables, and sentences have to be short as well. In turn, this means that coherence may be affected.
The highest value of Reading Ease and lowest Grade Level can be obtained if all words are monosyllabic, and sentences contain just one of such words each. Practically it’s impossible to obtain such a value without sacrificing coherence.
Try it. If you can create such a passage, drop me a message.