In Britain and America (and probably Australia), the average reading age of the population is about 13 years. This means that a magazine has to pitch its articles to this age group in order to be understood by the bulk of the population.

Readability is the quality of a written document that makes it easy to read and understand. From a grammatical viewpoint, readability relates to the choice of language and vocabulary, the complexity of sentence constructions and paragraph structure. But it can also be influenced by the visual aspects of a document including typeface, font size, line and paragraph spacing.

A number of grammarians have sought to devise formulas aimed at testing the readability of a document. Most of them use two variables—sentence length and ‘vocabulary load’ (which means either the average number of syllables per word or the rarity of a word).

There is a number of readability tests available designed to provide a statistical analysis of a particular text. Such tests are not infallible and need to be used with caution but they do provide a useful guide for authors.

Flesch-Kincaid Readability tests

The Flesch-Kinkaid readability tests were designed to indicate comprehension difficulty when reading a passage of contemporary English. There are two related tests:

• The Flesch Reading Ease and
• The Flesch-Kinkaid Grade Level.

Both tests originated in the USA and while they use the same core measures (word length and sentence length) they have different weighting factors such that the results of the two tests correlate inversely. A text with a comparatively high score on the Reading Ease test would normally have a lower score on the Grade Level test.

In the Flesch Reading Ease test, the higher the score the easier is the text to read.

The Gunning Fog Index

The Gunning Fog index provides an indication of the number of years of education needed by a reader in order to understand the text. This index computes readability according to the following formula

This index implies that short sentences written in plain English achieve a better score than longer sentences written in complex English.

Other indexes

There are a number of other indexes that try and achieve the same result. Each index applies a similar formula in order to compute readability based on the parameters specified. Word will compute the Flesh-Kincaid Grade Level (see below) automatically as part of its spelling and grammar check.

Applying readability tests

In a document of 50,000 words, a sampling of 100 words does not necessarily provide an accurate assessment of overall readability; however if a random sampling is undertaken every 10 pages or so, the result will give a better indication of the structure. This is not as hard as it may first appear since there are online applications, which can assist you in determining readability.

Some versions of Word will also allow you to check readability using the Flesh Kincaid index as part of the spelling and grammar check. However, earlier versions of Word (before Word 2007) do not score above Grade 12 and so its functionality of these versions is limited. You can turn on this feature from the Word Preferences palette (Figure 1).

One caveat about readability however, if the document is badly written and poorly structured in the first place, readability tests are not of much use. A final test of readability is best performed by a human as part of the edit process.

Table 1: Readability scores and reading ages

Source: Oxford Guide to Plain English

Readability tests are a useful means of benchmarking your writing but as we have already noted they are guides only and are not infallible. At the very least turn on your readability checker as part of your document proofing tools within Word for a quick test as you write.

Figure 1

Applying readability tests from within Word

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