and related to the above post...
Eighth-grade reading level common but tricky standard
AUGUST 8, 2008 (article)
You might have heard the standard advice that, to communicate effectively, we should aim to write at an eighth-grade reading level. And you might have puzzled over that advice with a few simple questions, such as "Why?" "How?" and "What - are you kidding me?"
Unfortunately, the answer to this last question is "No, I'm afraid not," because the answer to the first is this: According to various research reports, eighth grade represents the reading level of the average American.
That's not terribly impressive, of course, because it makes us sound like a nation of high school dropouts. But today's topic isn't our national literacy rate; it's how to get your writing projects' readability level where you want it.
If your goal is to create instruction manuals, newsletters, Web copy and so on that can be read and understood by the average eighth-grader - or at any particular grade level -
how do you know when you've hit the mark?
There are several formulas for estimating the readability level of text, and several return a grade-level measurement, such as the Automated Readability Index, the Gunning Fog Index, the Flesch-Kincaid Grade Level and the charmingly named SMOG, which stands for "Simple Measure of Gobbledygook."
the rest:
http://www.coloradoan.com/apps/pbcs..../1046/BUSINESS