Clear and consistent or total gobbledygook?

However, the systems used to check text readability have stayed the same for decades. Our research project, with partners Macquarie University, into readability in health information reveals the need for an updated approach.


The oldest and most widely used checker is the Flesch–Kincaid system. Developed in the 1940s, it uses a formula that combines the average word length with the average sentence length. This produces readability scores that align with United States school reading grades 3–12. This scale was later expanded to include grades 13–16 for college students and a 17th grade to identify specialised technical texts.

The Flesch–Kincaid system is known to become inaccurate at higher reading brackets because much of the underlying research framework is based on school children and assumes a low exposure to diverse language and terms. Scores above a Year 7 level of comprehension have often been called into question.


The SMOG – or Simple Measure of Gobbledygook – grade is the measure of readability most often used for checking health messages. Like the Flesch–Kincaid system, it breaks difficulty down into school-grade levels for easy comprehension. This system uses an approximate formula based on the count of words of 3 or more syllables over 30 sentences.

Unlike Flesch–Kincaid, SMOG is known to be more accurate at higher levels. But the Macquarie University research team has still questioned the validity of using syllable count as a measure of readability because it is difficult to obtain a consistent and accurate syllable count.

Fresh ideas

Macquarie University’s recent research into readability in health information aims to inform the development of more precise readability checking systems using advanced computational techniques to investigate the nuances of written text.

Macquarie is also looking at the reading experience of different audiences. Troublingly, neither Flesch–Kincaid nor SMOG account for the differences in reading experience between native and non-native English speakers – a distinction that the new research works to address. This is especially important because 1 in 4 Australians was born overseas.