a scheme by which the readability of a particular text may be evaluated; it is computed by adding the average sentence length (expressed in number of words per sentence) to the percentage of words with more than two syllables. [the fog index of the preceding sentence is 39 + 17.9 = 56.9; higher equals foggier]

When befogged, I am unable to do the math to determine degree.

When befogged, I am unable to do the mathfog index = 10.3
Ah, but Dr. Bill!fog index = 5.25 You *must do the math to find out whether you are befogged. fog index = 13.2

Dear Faldage: The fog creeps in on little cat feet. Like the girl who stuttered, and before she could say she was not that kind of girl, she was. (my apologies to Carl Sandburg) Write a software applet to do the testing.

...uh excuse me Sirs, I am not Milum. I am just a lackey choosen to tell the great tsuwm behind the curtain that it might be better to divide the total number of words into the total number of "three or betters". That way you wouldn't have to apply the Fog Index so often. The higher the number the greater the Fog.
Thank you,
Lester Lackey.

Note: The letter above has a perfect Fog Index of -0- (zero) or a Fog Index of .01937, depending on how many syllables are in "tsuwm".

"Stammering is the native eloquence of us fog people."
--Eugene O'Neill

Here's a typical one from my beloved shanks, if anyone wants to figure his out (I'm way too lazy.): For any name more recently imported (or brought to our notice) we should make every effort to achieve some semblance of accuracy - either through as phonetic a rendition as possible, or through accpetance of the form favoured by the native users of that language and name. From:
http://wordsmith.org/board/showthreaded.pl?Cat=&Board=miscellany&Number=23489 He wrote a couple of really, really long ones, but I couldn't find 'em.

Oh, my dear, this has made me miss you all the more--how can you not be here?

I do not agree. I mean, "readability" is not a well defined concept, since it depends on the knowledges of the reader.
To me, often short sentences, with short words, are more difficult to decypher than longer ones . For example, things like
Ain't get it?... or similar. I suppose that it happens because there is something to guess in the sentence, and I am not able to do that.

Ain't get it?... or similar.

Huh? I don't get it!

Oh, dear, E, I forgot that "ain't" for some reason changes the verb around it (at least sometimes). No wonder you're confused. You probably saw 'ain't got it', not ain't get it. "Ain't got it" = don't have it*, as in, "I ain't got that book you've been looking for" (though a person who uses the word ain't would probably say 'you been looking for, leaving off the 'have'). We would not say 'ain't have it', and I have no idea why.

*Unless they mean a colloquial meaning of "getting it": understanding. If someone explains a joke to me, then I "get it". If they explained it to me, then I "got it", meaning I understood it. We don't use the 'have' with this sense of 'get'. But there is yet another possibility, that I guess has to come from context. I could say, "I got the joke" and mean that I understood why it was funny. I could also say, "I got the joke" and mean that I, for example, got a friend to write down the joke that you had asked for--literally have it in my possession, that is. A further intricacy of this is that if I picked up a copy of the joke, it was in the past. I could say, "I got the joke", meaning "I picked it up an hour ago", or "I've got the joke", meaning, "Here it is, in my possession right now". Get it? Oh, if she does, people, it will be because of her extraordinary understanding! If anyone can make this muddle clearer, I wish you would.