“The most valuable of all talents is that of never using two words when one will do.”
Thomas Jefferson

“Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts.”
William Strunk, Jr.

Lots of people are checking out the “readability” of their writing and Juicy Studio (thanks Sue) has a readability test that also explains how each measure is calculated.

According to TechBrew, “readability metrics use factors like words per sentence, multisyllabic frequency, and so on. These are three of the more common ones:

• Flesch Reading Ease: Measures sentence structure and complexity to determine how easy it is to read without stopping and re-reading, etc. Higher is better, but between 60 and 70 is a good score.
• Flesch-Kincaid Grade: What grade of school you will have needed to complete to handle the writing style and structure. Needless to say, this doesn’t reflect subject matter. A score of 5 that deals with quantum mechanics will only apply to 5th graders who already understand quantum mechanics. A score of 17 is something best left to grad students, who will probably curse you for it.
• Gunning Fog: Measures the obfuscation of meaning; the lower the number, the better. TV Guide is a 6. Government cover-ups and legal papers score 20 to 30.”

Playing around with the readability tests led me to that was useful, Juicy Studio’s writing style guide and  The Guardian’s style guide (download as a pdf), which has useful tips on commonly misused words and grammatical errors.