Clear writing and readability is everything. It will make or break your engagement and success with the text.
Sometimes writing can get a bit thick and a bit foggy.
It’s not hard to get lost in words and sentences and florid text can scratch and leave us confused.
There is a reading test called the Gunning Fog Index and it can help you see the way.
This index tells us that short sentences written without the jargon and claptrap get a better score than long sentences written in difficult language.
The Fog Index comes from Robert Gunning, an American textbook publisher who observed that most high school graduates were unable to read. He said that newspapers and business documents were full of “fog” and unnecessary complicated.
This is why we tell students not to go OTT and write in flowery language. It’s why school policies need to be crystal clear.
How can you work out what score your writing gets? Well, there is a handy calculator that can do that for us and you can access that here. By the way, the passage you’ve just read scores 10.30 which for my intended audience is about right.
The Gunning’s Fog Index (or FOG) Readability Formula
Step 1: Take a sample passage of at least 100-words and count the number of exact words and sentences.
Step 2: Divide the total number of words in the sample by the number of sentences to arrive at the Average Sentence Length (ASL).
Step 3: Count the number of words of three or more syllables that are NOT (i) proper nouns, (ii) combinations of easy words or hyphenated words, or (iii) two-syllable verbs made into three with -es and -ed endings.
Step 4: Divide this number by the number or words in the sample passage.
Step 5: Add the ASL from Step 2 and the PHW from Step 4.
Step 6: Multiply the result by 0.4.
It uses the formula:
Reading Level (or Grade) = (Average number of words in sentences + % of words of three or more syllables) x 0.4
The ideal score for readability with the Fog index is 7 or 8. To give you an idea, the Times newspaper might edge 11-12 and technical text such as medical journals score 14–16.
The Fog Index isn’t perfect. For example, having a passage of simple, short sentences does not mean that the reading is any easier. Also, not all complex words are difficult.
But the Fog Index is a decent guide although by no means not the only one. Take a look at this blog which unpacks and unpicks the alternatives.