There are two ways of measuring the length of a word: counting letters or syllables. Since words are meant to be pronounced, I prefer syllables to letters. Five syllables for every three words yields an average word length of 5/3 or 1.66… as I have pointed out in an article ‘Syllable, Word And Sentence Length’ a year ago.
Well, the average word length is 5/3. The easy word length is less than 5/3. Though monosyllables are easy words, an excess of them may sound like baby-talk. So a word length of 3/3 or 1 syllable is not desirable. Therefore, the easy word length may be four syllables for every three words or simply 4/3.
The average word length of 5/3 targets average readers of everyday texts such as newspapers and business correspondence; the easy word length of 4/3 appeals to readers of children’s magazines and how-to books.
If we take a sample of only three words, then the 4/3 approach implies that there are two monosyllables, one disyllable and no polysyllable. But if we take six words, then there is room for a polysyllable (actually a tri-syllable) along with five monosyllables.
Martin Cutts tells us that the average sentence has 15-20 words. So if we take a sentence of 18 words written in the 4/3 style, then the average sentence can have a maximum of three polysyllables.
The 4/3 style, by limiting the number of polysyllables, makes the text more readable. It also simplifies the Flesch-Kincaid Index (FKI) for calculating the U.S. grade levels. Let us see how.
FKI = 0.39AWS (average words per sentence) + 11.8ASW (average syllables per word) – 15.59 = 0.39AWS + 11.8 (4/3) – 15.59 = 0.39AWS + 0.1433… = approximately W4 / 10; W4 is the number of words in four sentences.
Let us look at the opening sentence of this article: “There are two ways of measuring the length of a word: counting letters or syllables.” There are 15 words (11 monosyllables, 2 disyllables and 2 polysyllables) and 21 syllables. This is a 7/5 style, approximating to a 4/3 style. Since the sentence has 15 words, we may assume that the number of words in four sentences is 60. So, FKI = W4 / 10 = 60 /10 = 6 years of schooling.
Incidentally, mine own Strain Index (0.3 multiplied by the average number of syllables per sentence) returns a similar result. Since the sentence has 21 syllables, the Strain Index = 0.3 x 21 = 6.3 years of schooling.