Ever since my start in writing, I’ve thought Rudolph Flesh devised the Fog Index. I even vaguely remember someone assigning another “G” and calling it the Fogg Index.

Recently I learned that Robert Gunning was the author of the Fog Index and Rudolph Flesch devised the Readability Formula. Both teach writers to write more plainly and therefore make their articles more interesting to the average reader.

I found an article by Tom Davey of Canada, who has written four books and therefore has had occasion to put his theories into practice. He said Gunning’s Fog Index is probably the most used, as it results in how much education is required for comprehension. Low scores are desirable, scores above 20 are regarded as incomprehensible. Fog indices are on many computer programs, he says.

Here’s the way it works:

• Choose a medium-length paragraph, about 120 words.
• Count the number of words in the sample.
• Count the number of sentences.
• Divide the words by the sentences to get an average of words per sentence.
• Count each word of three or more syllables, excluding short words made longer by adding another short word (butterfly, for instance) or verbs that gained their extra syllables by adding ed or es; or words that begin with a capital letter or that are the first word in any sentence.

Once you have the polysyllable count, add that number to the word average.

Multiply by .4; that's point-4, or four-tenths.

The result is your Fogg Index number. The higher the number, the more difficult the reading. A score of 17 means only a graduate student could understand your copy; a nine means a ninth grader could understand. Business Week averages a 10, the Gettysburg Address gets 10 and Time and Newsweek work out to about 11.

The best way to improve your readability scores is to make “The Elements of Style,” a small but packed-with-good-rules book, one of your major resources in learning good writing. Early copies had only 75 or so pages but subsequent editions tip the scales over 80 pages. If you’re serious about writing, be sure to get a copy for your reference shelf.

(NCWritertoo is a retired journalist who worked as a writer for over 25 years. Email her at ncwritertoo@yahoo.com)